publicdata/nih-gov
2
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions
nih-gov/www.ncbi.nlm.nih.gov/books/n/webvision/ch31visualcortex/index.html
Scott Williams f361c7df98 Incremental update
2025-03-17 02:05:34 +00:00

1136 lines
No EOL
183 KiB
HTML
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<!-- AppResources meta begin -->
<meta name="paf-app-resources" content="" />
<script type="text/javascript">var ncbi_startTime = new Date();</script>
<!-- AppResources meta end -->
<!-- TemplateResources meta begin -->
<meta name="paf_template" content="" />
<!-- TemplateResources meta end -->
<!-- Logger begin -->
<meta name="ncbi_db" content="books" /><meta name="ncbi_pdid" content="book-part" /><meta name="ncbi_acc" content="NBK11524" /><meta name="ncbi_domain" content="webvision" /><meta name="ncbi_report" content="record" /><meta name="ncbi_type" content="fulltext" /><meta name="ncbi_objectid" content="" /><meta name="ncbi_pcid" content="/NBK11524/" /><meta name="ncbi_pagename" content="The Primary Visual Cortex - Webvision - NCBI Bookshelf" /><meta name="ncbi_bookparttype" content="chapter" /><meta name="ncbi_app" content="bookshelf" />
<!-- Logger end -->
<title>The Primary Visual Cortex - Webvision - NCBI Bookshelf</title>
<!-- AppResources external_resources begin -->
<link rel="stylesheet" href="/core/jig/1.15.2/css/jig.min.css" /><script type="text/javascript" src="/core/jig/1.15.2/js/jig.min.js"></script>
<!-- AppResources external_resources end -->
<!-- Page meta begin -->
<meta name="robots" content="INDEX,FOLLOW,NOARCHIVE" /><meta name="citation_inbook_title" content="Webvision: The Organization of the Retina and Visual System [Internet]" /><meta name="citation_title" content="The Primary Visual Cortex" /><meta name="citation_publisher" content="University of Utah Health Sciences Center" /><meta name="citation_date" content="2007/06/14" /><meta name="citation_author" content="Matthew Schmolesky" /><meta name="citation_pmid" content="21413385" /><meta name="citation_fulltext_html_url" content="https://www.ncbi.nlm.nih.gov/books/NBK11524/" /><link rel="schema.DC" href="http://purl.org/DC/elements/1.0/" /><meta name="DC.Title" content="The Primary Visual Cortex" /><meta name="DC.Type" content="Text" /><meta name="DC.Publisher" content="University of Utah Health Sciences Center" /><meta name="DC.Contributor" content="Matthew Schmolesky" /><meta name="DC.Date" content="2007/06/14" /><meta name="DC.Identifier" content="https://www.ncbi.nlm.nih.gov/books/NBK11524/" /><meta name="description" content="The human visual system can detect and discriminate between an incredibly diverse assortment of stimuli that may be chromatic or achromatic, in motion or not, patterned or unpatterned, two-dimensional or three. Remarkably, the neural end-product of visual stimuli impacting upon the retina is, in one sense, always the same. After the complexities of phototransduction, lateral interactions provided by horizontal and amacrine cells, and integration of signals by ganglion cell dendrites, only the constantly changing stream of action potentials propogating along ganglion cell axons is left to inform our visual perception. These seemingly identical signals must somehow be processed in the subcortex and cortex to create the full range of visual percepts we experience. How this is achieved is a puzzle that currently occupies the professional lives of thousands of researchers, and the basic framework of a solution has only begun to unfold in the last several decades." /><meta name="og:title" content="The Primary Visual Cortex" /><meta name="og:type" content="book" /><meta name="og:description" content="The human visual system can detect and discriminate between an incredibly diverse assortment of stimuli that may be chromatic or achromatic, in motion or not, patterned or unpatterned, two-dimensional or three. Remarkably, the neural end-product of visual stimuli impacting upon the retina is, in one sense, always the same. After the complexities of phototransduction, lateral interactions provided by horizontal and amacrine cells, and integration of signals by ganglion cell dendrites, only the constantly changing stream of action potentials propogating along ganglion cell axons is left to inform our visual perception. These seemingly identical signals must somehow be processed in the subcortex and cortex to create the full range of visual percepts we experience. How this is achieved is a puzzle that currently occupies the professional lives of thousands of researchers, and the basic framework of a solution has only begun to unfold in the last several decades." /><meta name="og:url" content="https://www.ncbi.nlm.nih.gov/books/NBK11524/" /><meta name="og:site_name" content="NCBI Bookshelf" /><meta name="og:image" content="https://www.ncbi.nlm.nih.gov/corehtml/pmc/pmcgifs/bookshelf/thumbs/th-webvision-lrg.png" /><meta name="twitter:card" content="summary" /><meta name="twitter:site" content="@ncbibooks" /><meta name="bk-non-canon-loc" content="/books/n/webvision/ch31visualcortex/" /><link rel="canonical" href="https://www.ncbi.nlm.nih.gov/books/NBK11524/" /><link rel="stylesheet" href="/corehtml/pmc/css/figpopup.css" type="text/css" media="screen" /><link rel="stylesheet" href="/corehtml/pmc/css/bookshelf/2.26/css/books.min.css" type="text/css" /><link rel="stylesheet" href="/corehtml/pmc/css/bookshelf/2.26/css/books_print.min.css" type="text/css" media="print" /><style type="text/css">p a.figpopup{display:inline !important} .bk_tt {font-family: monospace} .first-line-outdent .bk_ref {display: inline} .body-content h2, .body-content .h2 {border-bottom: 1px solid #97B0C8} .body-content h2.inline {border-bottom: none} a.page-toc-label , .jig-ncbismoothscroll a {text-decoration:none;border:0 !important} .temp-labeled-list .graphic {display:inline-block !important} .temp-labeled-list img{width:100%}</style><script type="text/javascript" src="/corehtml/pmc/js/jquery.hoverIntent.min.js"> </script><script type="text/javascript" src="/corehtml/pmc/js/common.min.js?_=3.18"> </script><script type="text/javascript" src="/corehtml/pmc/js/large-obj-scrollbars.min.js"> </script><script type="text/javascript">window.name="mainwindow";</script><script type="text/javascript" src="/corehtml/pmc/js/bookshelf/2.26/book-toc.min.js"> </script><script type="text/javascript" src="/corehtml/pmc/js/bookshelf/2.26/books.min.js"> </script><meta name="book-collection" content="NONE" />
<!-- Page meta end -->
<link rel="shortcut icon" href="//www.ncbi.nlm.nih.gov/favicon.ico" /><meta name="ncbi_phid" content="CE8D69CE7C99D1210000000000BE00A2.m_13" />
<meta name='referrer' content='origin-when-cross-origin'/><link type="text/css" rel="stylesheet" href="//static.pubmed.gov/portal/portal3rc.fcgi/4216699/css/3852956/3985586/3808861/4121862/3974050/3917732/251717/4216701/14534/45193/4113719/3849091/3984811/3751656/4033350/3840896/3577051/3852958/4008682/4207974/4206132/4062871/12930/3964959/3854974/36029/4128070/9685/3549676/3609192/3609193/3609213/3395586.css" /><link type="text/css" rel="stylesheet" href="//static.pubmed.gov/portal/portal3rc.fcgi/4216699/css/3411343/3882866.css" media="print" /></head>
<body class="book-part">
<div class="grid">
<div class="col twelve_col nomargin shadow">
<!-- System messages like service outage or JS required; this is handled by the TemplateResources portlet -->
<div class="sysmessages">
<noscript>
<p class="nojs">
<strong>Warning:</strong>
The NCBI web site requires JavaScript to function.
<a href="/guide/browsers/#enablejs" title="Learn how to enable JavaScript" target="_blank">more...</a>
</p>
</noscript>
</div>
<!--/.sysmessage-->
<div class="wrap">
<div class="page">
<div class="top">
<div id="universal_header">
<section class="usa-banner">
<div class="usa-accordion">
<header class="usa-banner-header">
<div class="usa-grid usa-banner-inner">
<img src="https://www.ncbi.nlm.nih.gov/coreutils/uswds/img/favicons/favicon-57.png" alt="U.S. flag" />
<p>An official website of the United States government</p>
<button class="non-usa-accordion-button usa-banner-button" aria-expanded="false" aria-controls="gov-banner-top" type="button">
<span class="usa-banner-button-text">Here's how you know</span>
</button>
</div>
</header>
<div class="usa-banner-content usa-grid usa-accordion-content" id="gov-banner-top" aria-hidden="true">
<div class="usa-banner-guidance-gov usa-width-one-half">
<img class="usa-banner-icon usa-media_block-img" src="https://www.ncbi.nlm.nih.gov/coreutils/uswds/img/icon-dot-gov.svg" alt="Dot gov" />
<div class="usa-media_block-body">
<p>
<strong>The .gov means it's official.</strong>
<br />
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you're on a federal
government site.
</p>
</div>
</div>
<div class="usa-banner-guidance-ssl usa-width-one-half">
<img class="usa-banner-icon usa-media_block-img" src="https://www.ncbi.nlm.nih.gov/coreutils/uswds/img/icon-https.svg" alt="Https" />
<div class="usa-media_block-body">
<p>
<strong>The site is secure.</strong>
<br />
The <strong>https://</strong> ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
</p>
</div>
</div>
</div>
</div>
</section>
<div class="usa-overlay"></div>
<header class="ncbi-header" role="banner" data-section="Header">
<div class="usa-grid">
<div class="usa-width-one-whole">
<div class="ncbi-header__logo">
<a href="/" class="logo" aria-label="NCBI Logo" data-ga-action="click_image" data-ga-label="NIH NLM Logo">
<img src="https://www.ncbi.nlm.nih.gov/coreutils/nwds/img/logos/AgencyLogo.svg" alt="NIH NLM Logo" />
</a>
</div>
<div class="ncbi-header__account">
<a id="account_login" href="https://account.ncbi.nlm.nih.gov" class="usa-button header-button" style="display:none" data-ga-action="open_menu" data-ga-label="account_menu">Log in</a>
<button id="account_info" class="header-button" style="display:none" aria-controls="account_popup" type="button">
<span class="fa fa-user" aria-hidden="true">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" width="20px" height="20px">
<g style="fill: #fff">
<ellipse cx="12" cy="8" rx="5" ry="6"></ellipse>
<path d="M21.8,19.1c-0.9-1.8-2.6-3.3-4.8-4.2c-0.6-0.2-1.3-0.2-1.8,0.1c-1,0.6-2,0.9-3.2,0.9s-2.2-0.3-3.2-0.9 C8.3,14.8,7.6,14.7,7,15c-2.2,0.9-3.9,2.4-4.8,4.2C1.5,20.5,2.6,22,4.1,22h15.8C21.4,22,22.5,20.5,21.8,19.1z"></path>
</g>
</svg>
</span>
<span class="username desktop-only" aria-hidden="true" id="uname_short"></span>
<span class="sr-only">Show account info</span>
</button>
</div>
<div class="ncbi-popup-anchor">
<div class="ncbi-popup account-popup" id="account_popup" aria-hidden="true">
<div class="ncbi-popup-head">
<button class="ncbi-close-button" data-ga-action="close_menu" data-ga-label="account_menu" type="button">
<span class="fa fa-times">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 48 48" width="24px" height="24px">
<path d="M38 12.83l-2.83-2.83-11.17 11.17-11.17-11.17-2.83 2.83 11.17 11.17-11.17 11.17 2.83 2.83 11.17-11.17 11.17 11.17 2.83-2.83-11.17-11.17z"></path>
</svg>
</span>
<span class="usa-sr-only">Close</span></button>
<h4>Account</h4>
</div>
<div class="account-user-info">
Logged in as:<br />
<b><span class="username" id="uname_long">username</span></b>
</div>
<div class="account-links">
<ul class="usa-unstyled-list">
<li><a id="account_myncbi" href="/myncbi/" class="set-base-url" data-ga-action="click_menu_item" data-ga-label="account_myncbi">Dashboard</a></li>
<li><a id="account_pubs" href="/myncbi/collections/bibliography/" class="set-base-url" data-ga-action="click_menu_item" data-ga-label="account_pubs">Publications</a></li>
<li><a id="account_settings" href="/account/settings/" class="set-base-url" data-ga-action="click_menu_item" data-ga-label="account_settings">Account settings</a></li>
<li><a id="account_logout" href="/account/signout/" class="set-base-url" data-ga-action="click_menu_item" data-ga-label="account_logout">Log out</a></li>
</ul>
</div>
</div>
</div>
</div>
</div>
</header>
<div role="navigation" aria-label="access keys">
<a id="nws_header_accesskey_0" href="https://www.ncbi.nlm.nih.gov/guide/browsers/#ncbi_accesskeys" class="usa-sr-only" accesskey="0" tabindex="-1">Access keys</a>
<a id="nws_header_accesskey_1" href="https://www.ncbi.nlm.nih.gov" class="usa-sr-only" accesskey="1" tabindex="-1">NCBI Homepage</a>
<a id="nws_header_accesskey_2" href="/myncbi/" class="set-base-url usa-sr-only" accesskey="2" tabindex="-1">MyNCBI Homepage</a>
<a id="nws_header_accesskey_3" href="#maincontent" class="usa-sr-only" accesskey="3" tabindex="-1">Main Content</a>
<a id="nws_header_accesskey_4" href="#" class="usa-sr-only" accesskey="4" tabindex="-1">Main Navigation</a>
</div>
<section data-section="Alerts">
<div class="ncbi-alerts-placeholder"></div>
</section>
</div>
<div class="header">
<div class="res_logo"><h1 class="res_name"><a href="/books/" title="Bookshelf home">Bookshelf</a></h1><h2 class="res_tagline"></h2></div>
<div class="search"><form method="get" action="/books/"><div class="search_form"><label for="database" class="offscreen_noflow">Search database</label><select id="database"><optgroup label="Recent"><option value="books" selected="selected" data-ac_dict="bookshelf-search">Books</option><option value="snp">SNP</option><option value="nlmcatalog">NLM Catalog</option><option value="pcsubstance" class="last">PubChem Substance</option></optgroup><optgroup label="All"><option value="gquery">All Databases</option><option value="assembly">Assembly</option><option value="biocollections">Biocollections</option><option value="bioproject">BioProject</option><option value="biosample">BioSample</option><option value="books" data-ac_dict="bookshelf-search">Books</option><option value="clinvar">ClinVar</option><option value="cdd">Conserved Domains</option><option value="gap">dbGaP</option><option value="dbvar">dbVar</option><option value="gene">Gene</option><option value="genome">Genome</option><option value="gds">GEO DataSets</option><option value="geoprofiles">GEO Profiles</option><option value="gtr">GTR</option><option value="ipg">Identical Protein Groups</option><option value="medgen">MedGen</option><option value="mesh">MeSH</option><option value="nlmcatalog">NLM Catalog</option><option value="nuccore">Nucleotide</option><option value="omim">OMIM</option><option value="pmc">PMC</option><option value="protein">Protein</option><option value="proteinclusters">Protein Clusters</option><option value="protfam">Protein Family Models</option><option value="pcassay">PubChem BioAssay</option><option value="pccompound">PubChem Compound</option><option value="pcsubstance">PubChem Substance</option><option value="pubmed">PubMed</option><option value="snp">SNP</option><option value="sra">SRA</option><option value="structure">Structure</option><option value="taxonomy">Taxonomy</option><option value="toolkit">ToolKit</option><option value="toolkitall">ToolKitAll</option><option value="toolkitbookgh">ToolKitBookgh</option></optgroup></select><div class="nowrap"><label for="term" class="offscreen_noflow" accesskey="/">Search term</label><div class="nowrap"><input type="text" name="term" id="term" title="Search Books. Use up and down arrows to choose an item from the autocomplete." value="" class="jig-ncbiclearbutton jig-ncbiautocomplete" data-jigconfig="dictionary:'bookshelf-search',disableUrl:'NcbiSearchBarAutoComplCtrl'" autocomplete="off" data-sbconfig="ds:'no',pjs:'no',afs:'no'" /></div><button id="search" type="submit" class="button_search nowrap" cmd="go">Search</button></div></div></form><ul class="searchlinks inline_list"><li>
<a href="/books/browse/">Browse Titles</a>
</li><li>
<a href="/books/advanced/">Advanced</a>
</li><li class="help">
<a href="/books/NBK3833/">Help</a>
</li><li class="disclaimer">
<a target="_blank" data-ga-category="literature_resources" data-ga-action="link_click" data-ga-label="disclaimer_link" href="https://www.ncbi.nlm.nih.gov/books/about/disclaimer/">Disclaimer</a>
</li></ul></div>
</div>
<!--<component id="Page" label="headcontent"/>-->
</div>
<div class="content">
<!-- site messages -->
<!-- Custom content 1 -->
<div class="col1">
</div>
<div class="container">
<div id="maincontent" class="content eight_col col">
<!-- Custom content in the left column above book nav -->
<div class="col2">
</div>
<!-- Book content -->
<!-- Custom content between navigation and content -->
<div class="col3">
</div>
<div class="document">
<div class="pre-content"><div><div class="bk_prnt"><p class="small">NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.</p><p>Kolb H, Fernandez E, Jones B, et al., editors. Webvision: The Organization of the Retina and Visual System [Internet]. Salt Lake City (UT): University of Utah Health Sciences Center; 1995-. </p></div><div class="iconblock clearfix whole_rhythm no_top_margin bk_noprnt"><a class="img_link icnblk_img" title="Table of Contents Page" href="/books/n/webvision/"><img class="source-thumb" src="/corehtml/pmc/pmcgifs/bookshelf/thumbs/th-webvision-lrg.png" alt="Cover of Webvision" height="100px" width="80px" /></a><div class="icnblk_cntnt eight_col"><h2>Webvision: The Organization of the Retina and Visual System [Internet].</h2><a data-jig="ncbitoggler" href="#__NBK11524_dtls__">Show details</a><div style="display:none" class="ui-widget" id="__NBK11524_dtls__"><div>Kolb H, Fernandez E, Jones B, et al., editors.</div><div>Salt Lake City (UT): <a href="http://webvision.med.utah.edu/" ref="pagearea=page-banner&amp;targetsite=external&amp;targetcat=link&amp;targettype=publisher">University of Utah Health Sciences Center</a>; 1995-.</div></div><div class="half_rhythm"><ul class="inline_list"><li style="margin-right:1em"><a class="bk_cntns" href="/books/n/webvision/">Contents</a></li></ul></div><div class="bk_noprnt"><form method="get" action="/books/n/webvision/" id="bk_srch"><div class="bk_search"><label for="bk_term" class="offscreen_noflow">Search term</label><input type="text" title="Search this book" id="bk_term" name="term" value="" data-jig="ncbiclearbutton" /> <input type="submit" class="jig-ncbibutton" value="Search this book" submit="false" style="padding: 0.1em 0.4em;" /></div></form></div></div><div class="icnblk_cntnt two_col"><div class="pagination bk_noprnt"><a class="active page_link prev" href="/books/n/webvision/brainvisual/" title="Previous page in this title">&lt; Prev</a><a class="active page_link next" href="/books/n/webvision/repair/" title="Next page in this title">Next &gt;</a></div></div></div></div></div>
<div class="main-content lit-style" itemscope="itemscope" itemtype="http://schema.org/CreativeWork"><div class="meta-content fm-sec"><h1 id="_NBK11524_"><span class="title" itemprop="name">The Primary Visual Cortex</span></h1><p class="contrib-group"><span itemprop="author">Matthew Schmolesky</span>.</p><p class="small">Created: <span itemprop="datePublished">May 1, 2005</span>; Last Update: <span itemprop="dateModified">June 14, 2007</span>.</p></div><div class="jig-ncbiinpagenav body-content whole_rhythm" data-jigconfig="allHeadingLevels: ['h2'],smoothScroll: false" itemprop="text"><div id="ch31visualcortex.Introduction"><h2 id="_ch31visualcortex_Introduction_">Introduction</h2><p>The human visual system can detect and discriminate between an incredibly diverse
assortment of stimuli that may be chromatic or achromatic, in motion or not,
patterned or unpatterned, two-dimensional or three. Remarkably, the neural
end-product of visual stimuli impacting upon the retina is, in one sense, always the
same. After the complexities of phototransduction, lateral interactions provided by
horizontal and amacrine cells, and integration of signals by ganglion cell
dendrites, only the constantly changing stream of action potentials propogating
along ganglion cell axons is left to inform our visual perception. These seemingly
identical signals must somehow be processed in the subcortex and cortex to create
the full range of visual percepts we experience. How this is achieved is a puzzle
that currently occupies the professional lives of thousands of researchers, and the
basic framework of a solution has only begun to unfold in the last several
decades.</p><p>To achieve an understanding of cortical and subcortical processing, we can ask two
basic questions about the signals leaving the retina:
</p><ul><li id="A4204" class="half_rhythm"><div>What are the discrete anatomical pathways that carry the signal?</div></li><li id="A4205" class="half_rhythm"><div>What information do the signals actually carry?</div></li></ul><p>The answers to these questions do not exist. That is, the answers we have thus far
are incomplete and, in many cases, conflicting. I point this out first because the
reader should be aware that vision research is a burgeoning field, where new
articles published every week bring additional details about how the brain copes
with its monumental task. To complicate matters, the animals most commonly studied
to understand visual processing (monkey, cat, ferret, rat, mouse, hamster,
zebrafish, goldfish, etc.) do not conveniently carry small, medium, large, and
extra-large copies of the same brain within their craniums. Although evolution has
settled upon many visual system designs that are shared by these species,
substantial differences also exist. For the purpose of this review, I will focus
almost entirely upon the macaque monkey visual system for the reason that it is one
of the most understood and best models that we have for human vision to date. I will
begin with a historical perspective on visual system research and continue by
attempting to answer the two basic questions posed above in relation to the primary
visual cortex, or V1.</p></div><div id="ch31visualcortex.Historical_Perspecti"><h2 id="_ch31visualcortex_Historical_Perspecti_">Historical Perspective</h2><p>The relationship between vision and the eye must have been correctly understood from
the earliest times of human existence. Surpassing this most basic understanding,
however, required careful dissection of the eye, optical fibers, and brain
structures of animals and/or humans. One view holds that the religious and social
doctrines of the Pre-Classical civilizations (e.g., Egyptians, Sumerians, Assyrians,
Babylonians, Hindus, Chinese, Indians, etc.) did not permit such dissections. The
more primitive herdsman and farmers surrounding the Mediterranean Sea did not have
such inhibitions and are believed to have studied basic anatomy, albeit
nonsystematically, during sacrificial rituals. These herdsman and farmers evolved a
terminology for the anatomical structures that they discovered.</p><p>Polyak (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.1">1</a>) maintains
that this terminology was quickly adopted by the Greeks of 600&#x02013;400 B.C.
when the study of anatomical organization was rigorously pursued. During this time,
physicians such as Hippocrates (460&#x02013;380 B.C.), Alkmaeon (520 B.C.), and
Anaxagoras (500 B.C.) carried out dissections of animal and human bodies and brains
and held opinions of some accuracy concerning brain function, such as movement,
sensation, and thinking.</p><p>The height of Greek medical scientific knowledge was reached during the Hellenistic
or Alexandrian period from 323 to 212 B.C. The most prolific of medical scientists
was the "Prince of Physicians" Galen (129&#x02013;201 A.D.) of Pergamon (present
day Turkey). As noted by Polyak (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.1">1</a>), Galen's contributions to the
understanding of human anatomy and physiology under normal and pathological
conditions were vast and provided a foundation for medicine in the Arab period and,
subsequently, the Revival in Europe during the late Middle Ages and Modern Times.
<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F1/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF1" rid-ob="figobch31visualcortexF1">Fig. 1</a> shows the Arab adaptation of
Galen&#x000b9;s ideas on the pathways of the visual sytem from eyes to
forebrain.</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF1" co-legend-rid="figlgndch31visualcortexF1"><a href="/books/NBK11524/figure/ch31visualcortex.F1/?report=objectonly" target="object" title="Figure 1" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF1" rid-ob="figobch31visualcortexF1"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf1.gif" src-large="/books/NBK11524/bin/visualcortexf1.jpg" alt="Figure 1. Diagrammatic representation of the visual system from the oldest existing copy of the &quot;Book of Optics&quot; by Ibn Al-Haitham, an Arab physicist written in the 11 century A." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF1"><h4 id="ch31visualcortex.F1"><a href="/books/NBK11524/figure/ch31visualcortex.F1/?report=objectonly" target="object" rid-ob="figobch31visualcortexF1">Figure 1</a></h4><p class="float-caption no_bottom_margin">Diagrammatic representation of the visual system from the oldest
existing copy of the "Book of Optics" by Ibn Al-Haitham, an Arab physicist
written in the 11 century A.D. From Polyak (1). </p></div></div><p>Although Galen accurately described much of the visual system gross anatomy, he did
not recognize the decussation of fibers at the optic chiasm, nor did he trace the
fibers to the dorsal lateral geniculate nucleus (LGNd) of the thalamus (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F1/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF1" rid-ob="figobch31visualcortexF1">Fig. 1</a>). Instead, he suggested
that they were connected to the lateral ventricles (which he named the "thalami").
This belief was consistent with the prevailing view on nerves in general at the
time, namely that they were hollow channels carrying various "spirits", such as the
visual spirit. Over 1,000 years later, the beliefs of humanist scientists such as
Leonardo Da Vinci (who pictorally described the same optic fiber to the lateral
ventricle pathway) (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F2/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF2" rid-ob="figobch31visualcortexF2">Fig. 2</a>) and Des Cartes (who promoted
the view of nerves carrying animal spirits) echoed Galen's teachings and demonstrate
how little progress had been made in such a long time.</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF2" co-legend-rid="figlgndch31visualcortexF2"><a href="/books/NBK11524/figure/ch31visualcortex.F2/?report=objectonly" target="object" title="Figure 2" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF2" rid-ob="figobch31visualcortexF2"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf2.gif" src-large="/books/NBK11524/bin/visualcortexf2.jpg" alt="Figure 2. Drawing by Leonardo DaVinci of the projection of the eyes to the ventricles of the brain." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF2"><h4 id="ch31visualcortex.F2"><a href="/books/NBK11524/figure/ch31visualcortex.F2/?report=objectonly" target="object" rid-ob="figobch31visualcortexF2">Figure 2</a></h4><p class="float-caption no_bottom_margin">Drawing by Leonardo DaVinci of the projection of the eyes to the
ventricles of the brain. From Polyak (1). </p></div></div><p>Following the Hellenistic period, the ethics supported during the first several
centuries of the Christian Era denied medical practitioners and scientists the right
to dissect human corpses. This stricture was expanded in the Dark Ages to include
the dissection of animals, and from this point until the 1600s, healers were forced
to rely almost entirely upon what little information they could glean from the
Classical period (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F3/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF3" rid-ob="figobch31visualcortexF3">Fig. 3</a>, <a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F4/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF4" rid-ob="figobch31visualcortexF4">Fig. 4</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF3" co-legend-rid="figlgndch31visualcortexF3"><a href="/books/NBK11524/figure/ch31visualcortex.F3/?report=objectonly" target="object" title="Figure 3" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF3" rid-ob="figobch31visualcortexF3"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf3.gif" src-large="/books/NBK11524/bin/visualcortexf3.jpg" alt="Figure 3. Binocular stereoscopic visual system as imagined by Des Cartes." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF3"><h4 id="ch31visualcortex.F3"><a href="/books/NBK11524/figure/ch31visualcortex.F3/?report=objectonly" target="object" rid-ob="figobch31visualcortexF3">Figure 3</a></h4><p class="float-caption no_bottom_margin">Binocular stereoscopic visual system as imagined by Des Cartes. The
two retinal images of the arrow are accurately, point for point, projected
upon the surface of the cerebral ventricles and thence to the centrally
located pineal gland, H, the supposed <a href="/books/NBK11524/figure/ch31visualcortex.F3/?report=objectonly" target="object" rid-ob="figobch31visualcortexF3">(more...)</a></p></div></div><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF4" co-legend-rid="figlgndch31visualcortexF4"><a href="/books/NBK11524/figure/ch31visualcortex.F4/?report=objectonly" target="object" title="Figure 4" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF4" rid-ob="figobch31visualcortexF4"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf4.gif" src-large="/books/NBK11524/bin/visualcortexf4.jpg" alt="Figure 4. Woodcut from the &quot;Fabrica&quot; (1555) by Vesalius showing the basal aspect of the human brain with the origins of the cranial nerves and the brain stem." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF4"><h4 id="ch31visualcortex.F4"><a href="/books/NBK11524/figure/ch31visualcortex.F4/?report=objectonly" target="object" rid-ob="figobch31visualcortexF4">Figure 4</a></h4><p class="float-caption no_bottom_margin">Woodcut from the "Fabrica" (1555) by Vesalius showing the basal
aspect of the human brain with the origins of the cranial nerves and the
brain stem. From Polyak (1). </p></div></div><p>Between 1600 and 1860 A.D., the most basic understanding of central visual system
anatomy and function was obtained. The partial decussation of optical fibers at the
chiasm was deduced. The projection of these fibers into the LGNd and the optic
radiations to the cortex were described. Accidental and experimentally induced
cortical lesions were correlated to symptomologies found in the patients and
experimental animals, respectively, leading to the notion of localized cortical
function. Cortical dissections were carefully performed, and the line of Gennari
(the dense, myelinated fiber bundle running through V1 layer 4B, named for its
discoverer) in the primary visual cortex was described (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F5/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF5" rid-ob="figobch31visualcortexF5">Fig. 5</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF5" co-legend-rid="figlgndch31visualcortexF5"><a href="/books/NBK11524/figure/ch31visualcortex.F5/?report=objectonly" target="object" title="Figure 5" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF5" rid-ob="figobch31visualcortexF5"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf5.gif" src-large="/books/NBK11524/bin/visualcortexf5.jpg" alt="Figure 5. Horizontal section of the brain showing the line of Gennari in the striate cortex." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF5"><h4 id="ch31visualcortex.F5"><a href="/books/NBK11524/figure/ch31visualcortex.F5/?report=objectonly" target="object" rid-ob="figobch31visualcortexF5">Figure 5</a></h4><p class="float-caption no_bottom_margin">Horizontal section of the brain showing the line of Gennari in the
striate cortex. From Polyak (1). </p></div></div><p>This striation gave rise to the term "striate cortex" to describe V1. Unstained
sections of cortex were examined on slides revealing the six cortical layers to
Baillarger. The notion of retinotopic organization in central structures gained wide
acceptance.</p><p>In the late 1800s and early 1900s, several advances in histological preparation led
to a boom in cellular studies of the visual cortex. Better chemical treatments were
found for hardening the brain prior to cutting thin slices; gross neuronal and fiber
staining dye protocols were developed (e.g., those of Weigert (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.2">2</a>) and Nissl (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.3">3</a>)); and the Golgi technique for
labeling individual cells, complete with their extensive axonal and dendritic
arborizations, was established (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F6/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF6" rid-ob="figobch31visualcortexF6">Fig. 6</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF6" co-legend-rid="figlgndch31visualcortexF6"><a href="/books/NBK11524/figure/ch31visualcortex.F6/?report=objectonly" target="object" title="Figure 6" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF6" rid-ob="figobch31visualcortexF6"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf6.gif" src-large="/books/NBK11524/bin/visualcortexf6.jpg" alt="Figure 6. Composite figure of a mosaic of camera lucida drawings showing the morphological features (size, location, and distribution) of the principal neuronal types of the human cortex." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF6"><h4 id="ch31visualcortex.F6"><a href="/books/NBK11524/figure/ch31visualcortex.F6/?report=objectonly" target="object" rid-ob="figobch31visualcortexF6">Figure 6</a></h4><p class="float-caption no_bottom_margin">Composite figure of a mosaic of camera lucida drawings showing the
morphological features (size, location, and distribution) of the principal
neuronal types of the human cortex. From rapid-Golgi preparations. Scale:
100 &#x003bc;m. </p></div></div><p>For the first time, researchers could view the intricacies of neuronal morphology and
the details of laminar differences. No single researcher contributed more in this
regard than Santiago Ram&#x000f3;n y Cajal (1852&#x02013;1934).
Ram&#x000f3;n y Cajal (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.4">4</a>) gave a detailed account of the cellular morphologies throughout the
cortex (visual and otherwise) using the Golgi method and his own modified silver
staining method. The incredible detail afforded by these techniques allowed
Ram&#x000f3;n y Cajal to suggest certain neural pathways and circuits and
theorize on the functional significance of the cortical constituents. The advent of
electron microscopy permitted researchers to describe the details of synaptic
connections. The development of "tracer" dyes that are taken up by distal fibers and
transported toward the cell body (retrograde tracers) or taken up by the
cell/dendrites and transported along the fibers to the distal terminals (anterograde
tracers) greatly enhanced the search for feedforward and feedback pathways in the
visual system. (Specific transsynaptic degeneration following lesions in nuclei
and/or fiber bundles was used previously, but with far less success.)</p><p>All of the progress described above is anatomical in nature. What about the function
of the visual pathways? How were researchers approaching this issue in the late
1800s and early 1900s? Clinical cases described over the centuries already pointed
to the functional specialization of discrete cortical areas. Experimental lesions
within the cortex confirmed this notion. Electrical stimulation of the cortex (e.g.,
Fritsch and Hitzig (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.5">5</a>)
on dog and monkey motor cortex) provided the <i>coup de grace</i> to the
doctrine of functional equivalence and established the theory of functional cerebral
localization in its place. Surgeons such as Penfield (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.6">6</a>) were mechanically stimulating the
brains of conscious patients during operations and recording the sensations evoked
(<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F7/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF7" rid-ob="figobch31visualcortexF7">Fig. 7</a>). The critical step in
obtaining a functional map of the visual system, however, came when researchers
moved from electrical stimulation to electrical recording.</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF7" co-legend-rid="figlgndch31visualcortexF7"><a href="/books/NBK11524/figure/ch31visualcortex.F7/?report=objectonly" target="object" title="Figure 7" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF7" rid-ob="figobch31visualcortexF7"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf7.gif" src-large="/books/NBK11524/bin/visualcortexf7.jpg" alt="Figure 7. Human brain labeled as to cortical areas during neurosurgery." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF7"><h4 id="ch31visualcortex.F7"><a href="/books/NBK11524/figure/ch31visualcortex.F7/?report=objectonly" target="object" rid-ob="figobch31visualcortexF7">Figure 7</a></h4><p class="float-caption no_bottom_margin">Human brain labeled as to cortical areas during neurosurgery. From
Penfield and Boldrey (6). </p></div></div><p>Scalp recordings of visual evoked potentials (VEPs) were used to map visually
responsive cortical areas and examine retinotopic organization and binocularity in
rabbit, cat, and monkey (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.7">7-9</a>). Simultaneously, microelectrodes were being used to study single
cells/fibers (or small groups) in the retina/optic tract (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.10">10</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.11">11</a>) and somatosensory cortex (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.12">12</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.13">13</a>). Hubel and Wiesel
first applied the single unit recording technique to the visual cortex of cats
(<a class="bk_pop" href="#ch31visualcortex.EXTYLES.14">14</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.15">15</a>) and monkeys (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.16">16-18</a>) with stunning
results. With this incredible series of experiments (for which David Hubel (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.19">19</a>) and Torston Wiesel
later won the Nobel Prize in 1982), the modern era of visual cortex research was
ushered in.</p><p>With this historical perspective in mind, we should turn our attention to the current
understanding of the primary visual cortex and its place in the visual pathways.</p></div><div id="ch31visualcortex.Which_Anatomical_Pat"><h2 id="_ch31visualcortex_Which_Anatomical_Pat_">Which Anatomical Pathways Carry the Visual Signal?</h2><div id="ch31visualcortex.Basic_Anatomy"><h3>Basic Anatomy</h3><p>The macaque primary visual cortex, like that of all mammals studied, resides in
the posterior pole of the occipital cortex (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F8/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF8" rid-ob="figobch31visualcortexF8">Fig. 8</a>).
V1 extends rostrally almost to the lunate sulcus and posterolaterally almost to
the inferior occipital sulcus; the V1/V2 border is met before either sulci. Much
of V1 is found within the calcarine sulci, and the limits of V1 within these
folds can be marked by the distinct appearance of V1 layer 4 (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F9/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF9" rid-ob="figobch31visualcortexF9">Fig. 9</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF8" co-legend-rid="figlgndch31visualcortexF8"><a href="/books/NBK11524/figure/ch31visualcortex.F8/?report=objectonly" target="object" title="Figure 8" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF8" rid-ob="figobch31visualcortexF8"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf8.gif" src-large="/books/NBK11524/bin/visualcortexf8.jpg" alt="Figure 8. Visual input to the brain goes from eye to LGN and then to primary visual cortex, or area V1, which is located in the posterior of the occipital lobe." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF8"><h4 id="ch31visualcortex.F8"><a href="/books/NBK11524/figure/ch31visualcortex.F8/?report=objectonly" target="object" rid-ob="figobch31visualcortexF8">Figure 8</a></h4><p class="float-caption no_bottom_margin">Visual input to the brain goes from eye to LGN and then to primary
visual cortex, or area V1, which is located in the posterior of the
occipital lobe. Adapted from Polyak (1). </p></div></div><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF9" co-legend-rid="figlgndch31visualcortexF9"><a href="/books/NBK11524/figure/ch31visualcortex.F9/?report=objectonly" target="object" title="Figure 9" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF9" rid-ob="figobch31visualcortexF9"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf9.gif" src-large="/books/NBK11524/bin/visualcortexf9.jpg" alt="Figure 9. Nissl-stained section to show the border between area 17 (V1) and area 18 (V2)." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF9"><h4 id="ch31visualcortex.F9"><a href="/books/NBK11524/figure/ch31visualcortex.F9/?report=objectonly" target="object" rid-ob="figobch31visualcortexF9">Figure 9</a></h4><p class="float-caption no_bottom_margin">Nissl-stained section to show the border between area 17 (V1) and
area 18 (V2). </p></div></div><p>The anatomy of the primate primary visual cortex has been worked out in great
detail. The three basic organizing principles of primate V1 are the: 1) laminar
and 2) columnar arrangement of excitatory and inhibitory neurons (an arrangement
shared with other neocortical areas) and 3) the regular spacing of
anatomical/functional compartments revealed by cytochrome oxidase (CO)
labeling.</p><p>Several simple facts and rules of thumb can be stated before addressing the
details of these anatomical features:</p><ul><li id="A4206" class="half_rhythm"><div>The six cortical layers introduced by Brodmann (layer 1 most dorsal,
layer 6 most ventral) have been subdivided time and again as additional
aspects of the neurons and their connections have been revealed.</div></li><li id="A4207" class="half_rhythm"><div>Layer 1 is nearly aneuronal, composed predominantly of dendritic and
axonal connections. In 1 mm<sup>3</sup> of V1 tissue, one could expect
to find approximately 4,700 neurons, 2,900 microglia, 3,400
oligodendrocytes and 49,000 astrocytes (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.20">20</a>). Of the neurons
present, over 80% are GABAergic (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.21">21</a>).</div></li><li id="A4208" class="half_rhythm"><div>Approximately 20% of the neurons in layers 2&#x02013;6 are inhibitory
interneurons (GABAergic) that make major contributions to the function
of V1 circuits but do not project axons outside of this area.</div></li><li id="A4209" class="half_rhythm"><div>Layers 2/3 (the "supergranular" layers) contain many excitatory
projection neurons that send axons to extrastriate cortical regions
(e.g., V2, V3, V4, MT, etc.).</div></li><li id="A4210" class="half_rhythm"><div>Layer 4 (the "granular" layer) is divided into four horizontal sublayers:
4A, 4B, 4C&#x003b1;, and 4C&#x003b2;. Layers 4C&#x003b1; and
4C&#x003b2; are the major recipients of LGNd innervation. The LGNd
magnocellular (M) and parvocellular (P) layers project to
4C&#x003b1; and the 4C&#x003b2;, respectively. Thus, the M and P
streams remain segregated at this stage (but see qualification
below).</div></li><li id="A4211" class="half_rhythm"><div>Layers 5/6 (the "infragranular" layers) contain many excitatory
projection neurons that innervate the LGNd to provide feedback to this
relay area.</div></li><li id="A4212" class="half_rhythm"><div>Labeling of V1 and V2 for CO content has revealed CO-rich and -poor
regions termed "blobs" (or puff, spots, or patches) and "interblobs" in
V1 and the thick, thin, and pale stripes in V2. The relevance of these
compartments is still a matter of some debate.</div></li><li id="A4213" class="half_rhythm"><div>CO blobs do not extend uniformly from the surface of layer 1 to the base
of layer 6. Instead, they concentrate in layers 3B, 4B, and 4C (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F10/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF10" rid-ob="figobch31visualcortexF10">Fig. 10</a>).</div></li><li id="A4214" class="half_rhythm"><div>Projections to and from the CO blobs and interblobs are relatively
distinct as follows (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F11/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF11" rid-ob="figobch31visualcortexF11">Fig. 11</a>):</div><ul><li id="A4215" class="half_rhythm"><div>P&#x003b2; (for primate P or midget ganglion cells) project
to the LGNd parvocellular layers (see the chapter on midget
pathways of the retina), which project to V1 layer 4C and then
project to the interblobs of V1 layers 2/3; and finally these
layers project to the pale stripes of the V2 geniculate.</div></li><li id="A4216" class="half_rhythm"><div>The blue-yellow ganglion cells (see the chapters on S-cone
pathways and color vision) project to the intercalated layers
and S/K (K for "koniocellular") layers of the LGNd, which
project to the blobs of V1 layers 2/3, which project to the thin
stripes of V2.</div></li><li id="A4217" class="half_rhythm"><div>P&#x003b1; (M cells or parasol ganglion cells) project to the
LGNd magnocellular layers and thence to layer 4C of V1. This
layer projects to the blobs of V1 layers 2/3 and also to layer
4B of V1. Layer 4B, in turn, projects to the mediotemporal area
(MT) and to the thick stripes of V2.</div></li></ul></li><li id="A4218" class="half_rhythm"><div>Layers 1 and 2 receive feedback inputs from extrastriate cortex.</div></li><li id="A4219" class="half_rhythm"><div>The neuroglia in the young adult macaque V1 account for 20-35% of all
cells (not including pericytes). The neuroglia can be divided into
oligodendrocytes (~7-10% of cells), astrocytes (~11-20% of cells), and
microglial cells (~1.5-3% of cells) (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.20">20</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.22">22</a>).</div></li></ul><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF10" co-legend-rid="figlgndch31visualcortexF10"><a href="/books/NBK11524/figure/ch31visualcortex.F10/?report=objectonly" target="object" title="Figure 10" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF10" rid-ob="figobch31visualcortexF10"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf10.gif" src-large="/books/NBK11524/bin/visualcortexf10.jpg" alt="Figure 10. Nissl (left) and cytochrome oxidase (right) labeled cross sections of the visual cortex of a macaque monkey, showing the individual layers." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF10"><h4 id="ch31visualcortex.F10"><a href="/books/NBK11524/figure/ch31visualcortex.F10/?report=objectonly" target="object" rid-ob="figobch31visualcortexF10">Figure 10</a></h4><p class="float-caption no_bottom_margin">Nissl (left) and cytochrome oxidase (right) labeled cross sections
of the visual cortex of a macaque monkey, showing the individual layers. </p></div></div><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF11" co-legend-rid="figlgndch31visualcortexF11"><a href="/books/NBK11524/figure/ch31visualcortex.F11/?report=objectonly" target="object" title="Figure 11" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF11" rid-ob="figobch31visualcortexF11"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf11.gif" src-large="/books/NBK11524/bin/visualcortexf11.jpg" alt="Figure 11. The projections of the small (P cells) and large (M cells) ganglion cells from the two eyes to parvocellular and magnocellular layers of the LGN, respectively." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF11"><h4 id="ch31visualcortex.F11"><a href="/books/NBK11524/figure/ch31visualcortex.F11/?report=objectonly" target="object" rid-ob="figobch31visualcortexF11">Figure 11</a></h4><p class="float-caption no_bottom_margin">The projections of the small (P cells) and large (M cells)
ganglion cells from the two eyes to parvocellular and magnocellular layers
of the LGN, respectively. </p></div></div></div><div id="ch31visualcortex.Neuronal_Constituent"><h3>Neuronal Constituents</h3><p>There are three basic types of neurons in the primate V1 (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F12/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF12" rid-ob="figobch31visualcortexF12">Fig.
12</a>):</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF12" co-legend-rid="figlgndch31visualcortexF12"><a href="/books/NBK11524/figure/ch31visualcortex.F12/?report=objectonly" target="object" title="Figure 12" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF12" rid-ob="figobch31visualcortexF12"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf12.gif" src-large="/books/NBK11524/bin/visualcortexf12.jpg" alt="Figure 12. Basic cell types in the monkey cerebral cortex." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF12"><h4 id="ch31visualcortex.F12"><a href="/books/NBK11524/figure/ch31visualcortex.F12/?report=objectonly" target="object" rid-ob="figobch31visualcortexF12">Figure 12</a></h4><p class="float-caption no_bottom_margin">Basic cell types in the monkey cerebral cortex. Left: spiny
neurons that include pyramidal cells and stellate cells (A). Spiny neurons
use the neurotransmitter glutamate (Glu). Right: smooth cells that use the
neurotransmitter GABA. B, cell with local <a href="/books/NBK11524/figure/ch31visualcortex.F12/?report=objectonly" target="object" rid-ob="figobch31visualcortexF12">(more...)</a></p></div></div><ul><li id="A4220" class="half_rhythm"><div>spiny pyramidal cells (excitatory)</div></li><li id="A4221" class="half_rhythm"><div>spiny stellate cells (excitatory)</div></li><li id="A4222" class="half_rhythm"><div>smooth or sparsely spinous interneurons (almost all are GABAergic)</div></li></ul><p>The pyramidal cells, as you might guess, have cell bodies that appear like
pyramids, have apical dendrites (that is, extending toward the white matter),
and their dendrites are covered with spines. Spiny stellate cells are generally
smaller, and their cell bodies more resemble a star shape. They also have spiny
dendrites (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F12/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF12" rid-ob="figobch31visualcortexF12">Fig. 12</a>A). The
interneurons have more rounded cell bodies and have little or no spines on their
dendrites. Over the years, anatomists have given more or less descriptive
appelations to a number of unique subtypes, which are briefly described
below.</p><ul><li id="A4223" class="half_rhythm"><div>Chandelier cell &#x02013; inhibitory; axons show characteristic
branching into vertical sections resembling candlesticks (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F12/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF12" rid-ob="figobch31visualcortexF12">Fig. 12</a>E).</div></li><li id="A4224" class="half_rhythm"><div>Neurogliaform cells &#x02013; inhibitory; resembling glial cells but
definitively neurons; axon and dendrites branch but remain in the locale
of the soma, giving rise to a dense spherical region of fibers (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F12/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF12" rid-ob="figobch31visualcortexF12">Fig. 12</a>G).</div></li><li id="A4225" class="half_rhythm"><div>Double bouquet cell &#x02013; inhibitory; axon collaterals and
bitufted dendrites extend vertically in a tight bundle (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F12/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF12" rid-ob="figobch31visualcortexF12">Fig. 12</a>C).
Antibodies to calbindin specifically mark these cells, and by using this
strategy, researchers have found that these cells are regularly spaced
in layer 3, thereby forming yet another columnar unit. There are
approximately 7 to 15 double bouquet cells per 10,000
&#x003bc;m<sup>2</sup> (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.23">23</a>).</div></li><li id="A4226" class="half_rhythm"><div>Basket cells (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.24">24</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.25">25</a>)
&#x02013; inhibitory; relatively large cell bodies extend myelinated
axonal branch laterally for a great distance. The axonal branches
terminate on pyramidal cell bodies and dendrites in a manner resembling
a basket. Dendrites extend vertically (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F12/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF12" rid-ob="figobch31visualcortexF12">Fig. 12</a>, D and H).</div></li><li id="A4227" class="half_rhythm"><div>Cajal-Retzius cells &#x02013; inhibitory; Cajal and Retzius found
this cell type independently in layer 1 of neonatal animals and humans,
respectively. They may or may not exist in the adult.</div></li><li id="A4228" class="half_rhythm"><div>Meynert cell &#x02013; excitatory; large pyramidal cell first
described by Meynert; the "outer" Meynert cell bodies are found in 4B
and are regularly distributed relative to pyramidal cell cones (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.22">22</a>)
(see below).
These cells project to area MT. The "inner" Meynert cell bodies are
regularly spaced at the layer 5/6 border, lying below CO interblobs.
These cells are also found in layer 6. These cells typically have
asymmetric, lateral dendritic arborizations, are highly direction
selective, and are also known to project to area MT.</div></li></ul><p>The cell types described above represent only a few of the more unique varieties.
Jennifer Lund and colleagues (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.26">26-29</a>)
have rigorously studied the presumptive interneurons of the macaque V1 using the
Golgi impregnation staining method. On the basis of a range of morphological
criteria (the laminar position of somata, axonal arborization, dendritic
arborization, pattern and extent of branching), they have described over 40
types of interneurons alone.</p><p>Additional low-density interneurons might remain unidentified. The classes that
have been described might be further divided based on chemical content and/or
physiological response properties (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F12/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF12" rid-ob="figobch31visualcortexF12">Fig. 12</a>). Alternatively, it should be
noted that many of the anatomically distinct types may be physiologically
indistinguishable from one another.</p></div><div id="ch31visualcortex.The_Cortical_Layers"><h3>The Cortical Layers</h3><p>Many numbering schemes exist for the neocortical layers in general and the layers
of V1 in particular. I have adopted the basic scheme of Brodmann, who defined
the cortical layers based on careful histology. I have also adopted the
refinements suggested by the work of Lund and colleagues (see below) (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F13/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF13" rid-ob="figobch31visualcortexF13">Fig. 13</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF13" co-legend-rid="figlgndch31visualcortexF13"><a href="/books/NBK11524/figure/ch31visualcortex.F13/?report=objectonly" target="object" title="Figure 13" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF13" rid-ob="figobch31visualcortexF13"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf13.gif" src-large="/books/NBK11524/bin/visualcortexf13.jpg" alt="Figure 13. Nissl stain of the visual cortex reveals the different layers quite clearly." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF13"><h4 id="ch31visualcortex.F13"><a href="/books/NBK11524/figure/ch31visualcortex.F13/?report=objectonly" target="object" rid-ob="figobch31visualcortexF13">Figure 13</a></h4><p class="float-caption no_bottom_margin">Nissl stain of the visual cortex reveals the different layers
quite clearly. </p></div></div><p>Layer 1 is composed of a dense network of synapses formed between the apical
dendrites of layer 2&#x02013;5B pyramidal cells (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.29">29</a>) and the
collected inputs from LGNd K layers (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.30">30</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.31">31</a>),
the pulvinar, feedback pathways from extrastriate areas, nonspecific thalamic
nuclei, and other subcortical regions. Thus, although layer 1 contains few
neurons, it is a networking layer that has a direct, concerted affect on the
firing properties of pyramidal cells in deeper layers.</p><p>The supragranular layers (2, 3A, and 3B) contain many somata and dendrites of
pyramidal cells. Layers 2 and 3A receive little thalamic inputs (the K layer
projection to V1 blobs is focused mainly in 3B). They do not receive direct
inputs from layer 4C, in contrast to layer 3B that receives a massive 4C input.
Layers 2 and 3A do contain many axons and dendrites of neurons found in all
other cortical layers.</p><p>Layer 4A shows up in the Nissl stain as a dark band of small, granule-like cells.
This and the lack of pyramidal cells set this layer apart from layer 3B.</p><p>Layer 4B is a cell-poor layer that contains a low density arrangement of
pyramidal cells&#x02014;the large outer Meynert cells. This layer receives a
strong input from the underlying 4C&#x003b1;, and the Meynert cells are
known to project directly to area MT as well as the superior colliculus (SC)
(<a class="bk_pop" href="#ch31visualcortex.EXTYLES.32">32</a>). Cells in
layer 4B also project to the thick CO stripes of V2, which in turn project to
MT. Thus, this layer plays a substantial role in conveying information in the M
pathway/dorsal stream.</p><p>Layer 4C is distinguished from 4B in part due to the great density of stellate
cell packing in this layer. Polyak (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.1">1</a>) divided 4C into the &#x003b1;
and &#x003b2; divisions, based solely on histology; upper 4C neurons are
more dispersed. Differences in geniculate innervation patterns (i.e., the M
layers of LGNd to 4C&#x003b1; and the P layers to 4C&#x003b2;) (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.33">33</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.34">34</a>),
the projection patterns of the 4C cells (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.35">35</a>) and
physiological properties (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.36">36</a>) have
overwhelmingly supported this division. Additional evidence has suggested that
the upper and lower divisions of 4C&#x003b1; may be distinct as well (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.26">26</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.33">33</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.37">37</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.38">38</a>).</p><p>4C&#x003b2; spiny stellate neurons provide a dense innervation of layers 4A
and 3B and sparse innervation in 4C, 5, and maybe 6 (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.35">35</a>). No direct
projections from 4C&#x003b2; to 3A, 4B, or 5B have been found (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.26">26</a>). In
contrast, as already noted, 4C&#x003b1; projects heavily to 4B.</p><p>Local layer 5A neurons do not project to 4B and only weakly innervate
4C&#x003b2;. They innervate all other layers. 5A neurons appear to project
primarily to 3B and 1 (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.26">26</a>).
Pyramidal neurons in 5B send recurrent axons to layer 3A (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.39">39</a>). Meynert cells at the 5/6
border and within layer 6 project to both MT and SC (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.40">40</a>).</p><p>Layer 6: It is known that neurons in layer 6 send recurrent axons into
4C&#x003b2; (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.39">39</a>). Other neurons (or possibly even the same ones) project axons
back to the LGNd (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.41">41</a>). Layer 6 also receives a direct input from the LGNd (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.42">42</a>), thereby
forming a neural loop.</p></div><div id="ch31visualcortex.V1_Cortical_Columns"><h3>V1 Cortical Columns</h3><p>The term "cortical column" refers to the notion that cells arranged vertically
from the surface of the cortex to the white matter might compose functional or
anatomical units. Thus, a cortical column can be defined on the basis of
anatomical features (e.g., stereotyped patterns of pyramidal cell apical
dendrite bundles), functional features (e.g., columns of cortical cells, all
responding to the same stimulus orientation), or both.</p><p>Many types of columns have been proposed including ocular dominance, orientation,
spatial frequency, and color columns. The details of these columnar arrangements
will be described in later sections dealing with the physiology of V1. However,
I will here briefly describe the ocular dominance columns to provide an example
of columnar arrangement in the primary visual cortex.</p></div><div id="ch31visualcortex.Ocular_Dominance_Col"><h3>Ocular Dominance Columns</h3><p>Visual signals from the two eyes remain segregated in the LGNd (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F11/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF11" rid-ob="figobch31visualcortexF11">Fig. 11</a>) and in the
geniculorecipient layers of area V1 (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F14/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF14" rid-ob="figobch31visualcortexF14">Fig.
14</a>). One can observe this segregation by measuring the
electrophysiological responses of the units in layer 4C. As the recording
electrode is moved within layer 4C, there is an abrupt shift as to which eye
drives the unit. In layer 4C, the shift from one eye to the other takes place
over a distance of less than 50 &#x003bc;m. Signals from these bands
converge on individual neurons in the superficial layers of the cortex, thereby
forming columns dominated by one eye or the other in an alternating fashion
(<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F15/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF15" rid-ob="figobch31visualcortexF15">Fig. 15</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF14" co-legend-rid="figlgndch31visualcortexF14"><a href="/books/NBK11524/figure/ch31visualcortex.F14/?report=objectonly" target="object" title="Figure 14" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF14" rid-ob="figobch31visualcortexF14"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf14.gif" src-large="/books/NBK11524/bin/visualcortexf14.jpg" alt="Figure 14. The signals from each eye are segregated into different ocular dominance columns within area V1, layer 4C." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF14"><h4 id="ch31visualcortex.F14"><a href="/books/NBK11524/figure/ch31visualcortex.F14/?report=objectonly" target="object" rid-ob="figobch31visualcortexF14">Figure 14</a></h4><p class="float-caption no_bottom_margin">The signals from each eye are segregated into different ocular
dominance columns within area V1, layer 4C. </p></div></div><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF15" co-legend-rid="figlgndch31visualcortexF15"><a href="/books/NBK11524/figure/ch31visualcortex.F15/?report=objectonly" target="object" title="Figure 15" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF15" rid-ob="figobch31visualcortexF15"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf15.gif" src-large="/books/NBK11524/bin/visualcortexf15.jpg" alt="Figure 15. The ocular dominance columns in area V1 can be visualized by using markers." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF15"><h4 id="ch31visualcortex.F15"><a href="/books/NBK11524/figure/ch31visualcortex.F15/?report=objectonly" target="object" rid-ob="figobch31visualcortexF15">Figure 15</a></h4><p class="float-caption no_bottom_margin">The ocular dominance columns in area V1 can be visualized by using
markers. When the marker is injected into one eye, it is transported via the
LGN nucleus to the cortex. The light bands in this tangential section show
the places where the marker was <a href="/books/NBK11524/figure/ch31visualcortex.F15/?report=objectonly" target="object" rid-ob="figobch31visualcortexF15">(more...)</a></p></div></div></div><div id="ch31visualcortex.Cytochrome_Oxidase_L"><h3>Cytochrome Oxidase Labeling</h3><p>CO is an integral transmembrane protein that is found in the inner mitochondrial
membrane. Because it acts to catalyze the generation of adenosine triphosphate
(ATP), which is itself an energy molecule used in an enormous range of cellular
processes; the amount of CO in a cell or nucleus can be used as an indicator of
cellular activity. In 1978, Margaret Wong-Riley discovered that, quite apart
from its use as an activity indicator, CO labeling in the primary visual cortex
reveals a striking array of CO-rich and -deficient regions (i.e., blobs and
interblobs) (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F16/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF16" rid-ob="figobch31visualcortexF16">Fig. 16</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF16" co-legend-rid="figlgndch31visualcortexF16"><a href="/books/NBK11524/figure/ch31visualcortex.F16/?report=objectonly" target="object" title="Figure 16" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF16" rid-ob="figobch31visualcortexF16"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf16.gif" src-large="/books/NBK11524/bin/visualcortexf16.jpg" alt="Figure 16. Diagrammatic representation of the relationships between CO &quot;blobs&quot;, layer 4 cones, and pyramidal cell modules." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF16"><h4 id="ch31visualcortex.F16"><a href="/books/NBK11524/figure/ch31visualcortex.F16/?report=objectonly" target="object" rid-ob="figobch31visualcortexF16">Figure 16</a></h4><p class="float-caption no_bottom_margin">Diagrammatic representation of the relationships between CO
"blobs", layer 4 cones, and pyramidal cell modules. A, three-dimensional
representation. The "blobs" in layer 2/3I are aligned in single rows along
the 400 &#x003bc;m-wide ocular dominance columns <a href="/books/NBK11524/figure/ch31visualcortex.F16/?report=objectonly" target="object" rid-ob="figobch31visualcortexF16">(more...)</a></p></div></div><p>Presumably, these regions reflect stable differences in energy consumption in two
populations of neurons that were previously undistinguished. Assuming this were
true, what other differences might exist between blobs and interblobs? It should
be noted that dense CO staining does not exist throughout the entire cortical
depth. Instead, CO blobs are most visible in layers 3B, 4A, and 4C. Be that as
it may, if these dense regions were in fact different from their CO-deficient
neighbors in some way, the cells directly above and below rich and poor regions
might also show differences in connectivity and functional characteristics,
correlating with the cells above and below them.</p><p>For instance, blobs in layer 3B have been shown to correspond to specific
geniculate innervation in macaques (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.43">43</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.44">44</a>). Boyd and Casagrande (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.45">45</a>)
found recently that V1 cells projecting to MT in bush babies and owl monkeys
were more numerous below the CO blobs of layer 3B than below the interblobs.
Similar data in macaque monkeys also shows clustering of MT projecting cells in
periodical steps through the lateral extent of V1 (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.46">46-48</a>) but did not find a
correlation between these clusters and the CO (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F17/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF17" rid-ob="figobch31visualcortexF17">Fig. 17</a>
and <a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F18/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF18" rid-ob="figobch31visualcortexF18">Fig. 18</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF17" co-legend-rid="figlgndch31visualcortexF17"><a href="/books/NBK11524/figure/ch31visualcortex.F17/?report=objectonly" target="object" title="Figure 17" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF17" rid-ob="figobch31visualcortexF17"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf17.gif" src-large="/books/NBK11524/bin/visualcortexf17.jpg" alt="Figure 17. Schematic drawing of the visual cortex to show neurons, layers, columns, and CO blobs." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF17"><h4 id="ch31visualcortex.F17"><a href="/books/NBK11524/figure/ch31visualcortex.F17/?report=objectonly" target="object" rid-ob="figobch31visualcortexF17">Figure 17</a></h4><p class="float-caption no_bottom_margin">Schematic drawing of the visual cortex to show neurons, layers,
columns, and CO blobs. </p></div></div><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF18" co-legend-rid="figlgndch31visualcortexF18"><a href="/books/NBK11524/figure/ch31visualcortex.F18/?report=objectonly" target="object" title="Figure 18" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF18" rid-ob="figobch31visualcortexF18"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf18.gif" src-large="/books/NBK11524/bin/visualcortexf18.jpg" alt="Figure 18. Reconstructions of neurobiotin-injected V1 4C cells that have dendrites confined to layer 4C and dense axonal terminations in interblobs (A, B) or dendrites extending into layer 4C and dense axonal terminations in both blobs and interblobs." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF18"><h4 id="ch31visualcortex.F18"><a href="/books/NBK11524/figure/ch31visualcortex.F18/?report=objectonly" target="object" rid-ob="figobch31visualcortexF18">Figure 18</a></h4><p class="float-caption no_bottom_margin">Reconstructions of neurobiotin-injected V1 4C cells that have
dendrites confined to layer 4C and dense axonal terminations in interblobs
(A, B) or dendrites extending into layer 4C and dense axonal terminations in
both blobs and interblobs. From Yabuta <a href="/books/NBK11524/figure/ch31visualcortex.F18/?report=objectonly" target="object" rid-ob="figobch31visualcortexF18">(more...)</a></p></div></div></div><div id="ch31visualcortex.Feedforward_and_Feed"><h3>Feedforward and Feedback Pathways</h3><p>The signals from the two retinas are communicated to area V1 via the LGN. In the
macaque monkey, after the signals are processed in V1 they are communicated via
multiple pathways to the 30+ visually responsive, extrastriate cortical areas
(<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F19/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF19" rid-ob="figobch31visualcortexF19">Fig. 19</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF19" co-legend-rid="figlgndch31visualcortexF19"><a href="/books/NBK11524/figure/ch31visualcortex.F19/?report=objectonly" target="object" title="Figure 19" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF19" rid-ob="figobch31visualcortexF19"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf19.gif" src-large="/books/NBK11524/bin/visualcortexf19.jpg" alt="Figure 19. Much of V1 is located in the calcarine sulci, and its relationship to other brain areas is best shown by unfolding the brain and showing it flattened open." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF19"><h4 id="ch31visualcortex.F19"><a href="/books/NBK11524/figure/ch31visualcortex.F19/?report=objectonly" target="object" rid-ob="figobch31visualcortexF19">Figure 19</a></h4><p class="float-caption no_bottom_margin">Much of V1 is located in the calcarine sulci, and its relationship
to other brain areas is best shown by unfolding the brain and showing it
flattened open. The visually responsive areas of the macaque monkey are
shown in color. From Van Essen et al. (78). <a href="/books/NBK11524/figure/ch31visualcortex.F19/?report=objectonly" target="object" rid-ob="figobch31visualcortexF19">(more...)</a></p></div></div><p>Anatomical hierarchical models place the visual cortical areas into a multi-level
processing model based upon the pattern of feedforward, lateral, and feedback
pathways found in each area. In general, feedforward pathways are considered to
be those that project from the supragranular layers of one area and terminate in
layer 4 of the target area. In contrast, feedback projections are those that
arise from the infragranular layers of one area and terminate outside of layer 4
in the target area (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.49">49-51</a>).</p><p>In the previous sections, I have described the anatomical borders of V1, the
cells that exist in this area, the arrangement of those cells in layers,
columns, and CO compartments, and I have hinted at the visual pathways that
course into and out of V1. It is true that visual information is passed from the
retina to the LGNd to V1 to the higher cortical areas and that the higher areas
project back to V1 and V1 to the LGNd (there are no efferent projections to the
primate retina). However, although this view of visual processing is accurate,
it does not capture the wealth of upstream and downstream connections found in
V1.</p><p>Direct feedforward projections to V1 originate from the pulvinar, LGNd,
claustrum, nucleus paracentralis, raphe system, locus coeruleus, and the nucleus
basalis of Meynert (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.31">31</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.33">33</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.43">43</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.52">52-57</a>).</p><p>Direct feedforward projections from V1 extend to V2, V3, V5 or MT, MST, and FEF
(<a class="bk_pop" href="#ch31visualcortex.EXTYLES.41">41</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.46">46-48</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.58">58-63</a>).</p><p>Direct feedback projections to V1 originate from V2, V3, V4, V5 or MT, MST, FEF,
LIP, and inferotemporal cortex (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.47">47-49</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.57">57</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.61">61</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.62">62</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.64">64</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.65">65</a>).</p><p>Direct feedback projections from V1 extend to SC, LGNd, pulvinar, and pons (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.32">32</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.41">41</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.54">54</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.66">66</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.67">67</a>).</p><p>The connections listed above represent only a subset of the direct and indirect
projections that carry signals into and out of the primary visual cortex and do
not even begin to describe the extensive lateral connections within V1
itself.</p></div></div><div id="ch31visualcortex.What_Information_Doe"><h2 id="_ch31visualcortex_What_Information_Doe_">What Information Does the Visual Signal Carry?</h2><p>We now know the arrangement of neurons, dendrites, and axons in the layers, columns,
and CO compartments of V1. We know many of the pathways extending into and out of V1
involving the retina, subcortex, and extrastriate cortex. We can imagine light
impinging upon the eye and, from this origin point, a cascade of action potentials
streaming from neuron to neuron, area to area&#x02014; forward, lateral, and
back again. In the abstract, we know that it is these signals that are responsible
for our vision of the external world. But how do these millions of patterned spikes
resolve themselves into an actual percept? A partial answer is to consider that
every image can itself be broken down into components (e.g., lines, colors,
textures, shades, and motion, etc.) and that visual cortical neurons are specialized
to detect only a subset of these components.</p><div id="ch31visualcortex.Receptive_Field_Prop"><h3>Receptive Field Properties</h3><p>Each cell in the visual cortex has a receptive field (RF), a discrete area in
space relative to the fovea where the presentation or removal of a visual
stimulus will cause cellular activation. By definition, stimuli presented
outside of this receptive field will neither increase nor decrease the ongoing
activity of that individual cell. The location and size of a RF can be
considered among the most basic of RF properties.</p></div><div id="ch31visualcortex.Retinotopic_Maps_in_"><h3>Retinotopic Maps in V1</h3><p>The spatial position of the ganglion cells within the retina is preserved by the
spatial organization of the neurons within the LGN layers. The posterior LGN
contains neurons whose RF are near the fovea. Progressing from posterior to
anterior, the RF locations become increasingly peripheral in the retina (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.68">68</a>). This
spatial layout is called retinotopic organization because the topological
organization of the RFs in the LGN parallels the organization of the retina.</p><p>The signals in area V1 are also retinotopically arranged. From electrophysiology
in monkeys, one can measure the location of RFs with an electrode that
penetrates tangentially through layer 4C, transversing through the ocular
dominance columns. The RF centers of neurons along this path correspond
systematically to locations from the fovea to the periphery. This trend is
interrupted locally by small, abrupt jumps at the ocular dominance borders.
Thus, the striate cortex retains the retinotopic map of the contralateral visual
field that is developed in the LGN.</p></div><div id="ch31visualcortex.Orientation_and_Dire"><h3>Orientation and Direction Selectivity</h3><p>V1 is the first site where strong orientation and direction selectivities are
observed in the macaque monkey (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.16">16</a>). Although
the vast majority of V1 cells show some degree of orientation selectivity, only
approximately 25-35% of V1 cells are strongly directionally selective (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.69">69</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.70">70</a>). The
classic method for testing orientation and direction selectivity is to measure
the spike rate of a single cell in response to drifting oriented luminance bars
and/or drifting luminance spots (see Fig. 21).</p><p>The concept of an orientation column can be easily appreciated by examining <a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F20/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF20" rid-ob="figobch31visualcortexF20">Fig. 20</a> and <a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F21/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF21" rid-ob="figobch31visualcortexF21">Fig. 21</a>.
When an electrode is lowered into V1 at an angle relatively parallel to the
cortical layers (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F22/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF22" rid-ob="figobch31visualcortexF22">Fig. 22</a>), the orientation
selectivities of the cells encountered vary systematically, where adjacent
cellular regions share approximate orientation preferences.</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF20" co-legend-rid="figlgndch31visualcortexF20"><a href="/books/NBK11524/figure/ch31visualcortex.F20/?report=objectonly" target="object" title="Figure 20" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF20" rid-ob="figobch31visualcortexF20"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf20.gif" src-large="/books/NBK11524/bin/visualcortexf20.jpg" alt="Figure 20. The unfolded striate cortex has a shape like a pear." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF20"><h4 id="ch31visualcortex.F20"><a href="/books/NBK11524/figure/ch31visualcortex.F20/?report=objectonly" target="object" rid-ob="figobch31visualcortexF20">Figure 20</a></h4><p class="float-caption no_bottom_margin">The unfolded striate cortex has a shape like a pear. It would be a
quarter sphere if the visual fields were equally represented everywhere, but
instead it is greatly distorted by the disproportionate representation of
parts near the center of gaze (fovea), <a href="/books/NBK11524/figure/ch31visualcortex.F20/?report=objectonly" target="object" rid-ob="figobch31visualcortexF20">(more...)</a></p></div></div><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF21" co-legend-rid="figlgndch31visualcortexF21"><a href="/books/NBK11524/figure/ch31visualcortex.F21/?report=objectonly" target="object" title="Figure 21" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF21" rid-ob="figobch31visualcortexF21"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf21.gif" src-large="/books/NBK11524/bin/visualcortexf21.jpg" alt="Figure 21. A tuning curve and corresponding polar plot obtained from two macaque V1 cells in response to drifting luminance bars of systematically varied orientation and direction." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF21"><h4 id="ch31visualcortex.F21"><a href="/books/NBK11524/figure/ch31visualcortex.F21/?report=objectonly" target="object" rid-ob="figobch31visualcortexF21">Figure 21</a></h4><p class="float-caption no_bottom_margin">A tuning curve and corresponding polar plot obtained from two
macaque V1 cells in response to drifting luminance bars of systematically
varied orientation and direction. The responses of one orientation selective
cell and one nonselective cell are provided <a href="/books/NBK11524/figure/ch31visualcortex.F21/?report=objectonly" target="object" rid-ob="figobch31visualcortexF21">(more...)</a></p></div></div><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF22" co-legend-rid="figlgndch31visualcortexF22"><a href="/books/NBK11524/figure/ch31visualcortex.F22/?report=objectonly" target="object" title="Figure 22" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF22" rid-ob="figobch31visualcortexF22"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf22.gif" src-large="/books/NBK11524/bin/visualcortexf22.jpg" alt="Figure 22. One extensive electrode penetration in macaque V1." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF22"><h4 id="ch31visualcortex.F22"><a href="/books/NBK11524/figure/ch31visualcortex.F22/?report=objectonly" target="object" rid-ob="figobch31visualcortexF22">Figure 22</a></h4><p class="float-caption no_bottom_margin">One extensive electrode penetration in macaque V1. The short,
near-vertical lines represent recording sites, and polar plots for each site
are indicated. This figure shows the preferred orientation of each cell in
relation to the cortical layers, CO compartments <a href="/books/NBK11524/figure/ch31visualcortex.F22/?report=objectonly" target="object" rid-ob="figobch31visualcortexF22">(more...)</a></p></div></div><p>Such recordings led Hubel and Wiesel to propose models of functional organization
like the one shown in <a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F23/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF23" rid-ob="figobch31visualcortexF23">Fig. 23</a>.</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF23" co-legend-rid="figlgndch31visualcortexF23"><a href="/books/NBK11524/figure/ch31visualcortex.F23/?report=objectonly" target="object" title="Figure 23" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF23" rid-ob="figobch31visualcortexF23"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf23.gif" src-large="/books/NBK11524/bin/visualcortexf23.jpg" alt="Figure 23. The ice-cube model of the cortex." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF23"><h4 id="ch31visualcortex.F23"><a href="/books/NBK11524/figure/ch31visualcortex.F23/?report=objectonly" target="object" rid-ob="figobch31visualcortexF23">Figure 23</a></h4><p class="float-caption no_bottom_margin">The ice-cube model of the cortex. It illustrates how the cortex is
divided, and at the same time, into two kinds of slabs, one set of ocular
dominance (left and right) and one set for orientation. The model should not
be taken literally: Neither set is <a href="/books/NBK11524/figure/ch31visualcortex.F23/?report=objectonly" target="object" rid-ob="figobch31visualcortexF23">(more...)</a></p></div></div><p>Recently, the orientation columns of V1 first described by Hubel and Wiesel have
also been recast into more complex geometries, such as partial columns ("slabs")
and pinwheels, as dictated by the increasing volumes of evidence (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.71">71</a>).</p></div><div id="ch31visualcortex.Binocularity_and_Bin"><h3>Binocularity and Binocular Disparity</h3><p>Hubel and Wiesel (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.15">15</a>) first demonstrated the presence of cells in primate V1 that
responded preferentially to visual stimulation in both eyes as opposed to one
eye alone. They classified cells using a 7-point scale where:</p><ul><li id="A4229" class="half_rhythm"><div>1 &#x02013; cells excited by the contralateral eye alone.</div></li><li id="A4230" class="half_rhythm"><div>2 &#x02013; cells with a strong bias for contralateral
stimulation.</div></li><li id="A4231" class="half_rhythm"><div>3 &#x02013; cells with a weak bias for contralateral stimulation.</div></li><li id="A4232" class="half_rhythm"><div>4 &#x02013; cells that responded maximally to stimulation in both
eyes.</div></li><li id="A4233" class="half_rhythm"><div>5 &#x02013; cells with a weak bias for ipsilateral stimulation.</div></li><li id="A4234" class="half_rhythm"><div>6 &#x02013; cells with a strong bias for ipsilateral stimulation.</div></li><li id="A4235" class="half_rhythm"><div>7 &#x02013; cells excited by the ipsilateral eye alone.</div></li></ul><p>The proportion of monocular cells (points 1, 2, 6, and 7) <i>versus</i>
binocular cells (points 3, 4, and 5) was found to vary with the layer in which
cells were recorded. Cells in the retinogeniculato-recipient layers
4C&#x003b1; and 4C&#x003b2; were found to be exclusively monocular.
Anatomical studies have since shown that these cells receive monocular inputs
from the LGNd that do not converge from the alternating layers (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.34">34</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.39">39</a>).</p><p>What might be the usefulness of binocular cells? When an observer fixates on a
visual object, the image of this object is positioned on corresponding regions
of the two retinas. At the same time, however, objects in front of and behind
the fixation point create images that lie on non-corresponding regions of the
two retinas. The degree to which the images are non-corresponding (as measured
by difference scores in retinal eccentricity for instance) is defined as
binocular disparity. The ability to use binocular disparity to determine the
distance of an object from oneself, and its relation to the fixation plane, is
called stereopsis.</p><p>Hubel and Wiesel first described the presence of neurons in V1 that are sensitive
to binocular disparity. That is, some neurons may show maximal firing rates when
a stimulus has positive disparity and weak or even inhibited (below baseline)
firing rates to 0 disparity stimuli (in the fixation plane) or negative
disparity stimuli. These cells would be described as disparity sensitive and
negative disparity tuned. If the tuning were reasonably sharp, the cell might be
described as negative disparity selective, i.e., it responds soley, not simply
preferentially, to negative disparity. We now know the percentage of
disparity-sensitive cells and the proportion of positive, negative, and
0-disparity tuned cells. Clearly, there are no disparity tuned cells in layers
4C&#x003b1; and 4C&#x003b2; because binocularity is a prerequisite for
disparity sensitivity. As Livingstone (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.72">72</a>) noted, it is safe to assume
that negative and positive disparity selective cells are involved in stereopsis.
Of the 0-disparity tuned cells, all may be involved in stereopsis or,
alternatively, perhaps only those with very narrow tuning (i.e., selective ones)
contribute to this perceptual ability (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.73">73</a>). The work of DeAngelis,
Newsome, and Cumming (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.74">74</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.75">75</a>)
elegantly addresses this issue by attempting to alter stereopsis in trained
monkeys by microstimulating subregions of disparity-tuned cells in area MT.</p></div><div id="ch31visualcortex.Response_Timing_in_t"><h3>Response Timing in the Visual Pathways</h3><p>Another feature of visually evoked, single-cell response that is currently
gaining attention is timing. The order in which visual areas become active and
the range of activation times within any given area are important issues. As
described above, a prevailing model of primate vision proposes hierarchical
stages of visual areas based on anatomical connectivity (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.49">49</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.50">50</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.76">76-78</a>).
There is no doubt that a single stimulus initiates a characteristic flow of
neuronal discharge from the retina to the LGNd to V1 in a hierarchical manner.
Unfortunately, the complexity of corticocortical connections and functional
differentiation in primate visual streams renders further predictions highly
speculative (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.51">51</a>).</p><p>We could hypothesize, for instance, that the heavily myelinated path from V1 to
MT would lead to fast activation of this area. However, would all MT cells be
activated in this manner, or would others wait for activation via the more
indirect V1 to V2 to MT route? Many studies have reported response onset
latencies from a single visual area. Using these data to construct a chart of
activation times across the visual system, however, reveals a host of
complications (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.79">79</a>).</p><p>To begin with, the vast majority of studies that report latencies do so for only
one or two visual areas. An activation analysis in 10 visual areas, therefore,
might involve cross-comparisons between 5 and 10 separate studies. In one such
comparison, we might conclude that, on average, V1 cells become active long
before cells in the frontal eye field area (FEF) (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.80">80</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.81">81</a>). In
another such comparison, we would be forced to conclude the opposite (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.82">82</a>) (for a review,
see Nowak and Bullier (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.79">79</a>)).</p><p>The cause for this seeming discrepancy, and many others like it, is undoubtedly
the use of different experimental and data analysis protocols. The visual
stimuli used (flashing <i>versus</i> moving; spot, bar, grating, or
otherwise; low <i>versus</i> high luminance or contrast, etc.), animal
preparation used (anesthetized or not), and data analysis strategy taken for
marking latencies (qualitative or quantitative, etc.) all vary across the
existing reports.</p><p>Consequently, in a recent study, we sought to remove these confounds by obtaining
onset latencies from many primate visual areas using the same experimental and
analytical techniques (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.83">83</a>). The
results demonstrated that the two major functional streams in the primate visual
system (the M/dorsal stream involved in motion perception and tracking and the
P/ventral stream involved in object recognition and color coding) respond with
very different time courses (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F24/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF24" rid-ob="figobch31visualcortexF24">Fig. 24</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF24" co-legend-rid="figlgndch31visualcortexF24"><a href="/books/NBK11524/figure/ch31visualcortex.F24/?report=objectonly" target="object" title="Figure 24" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF24" rid-ob="figobch31visualcortexF24"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf24.gif" src-large="/books/NBK11524/bin/visualcortexf24.jpg" alt="Figure 24. Onset latencies." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF24"><h4 id="ch31visualcortex.F24"><a href="/books/NBK11524/figure/ch31visualcortex.F24/?report=objectonly" target="object" rid-ob="figobch31visualcortexF24">Figure 24</a></h4><p class="float-caption no_bottom_margin">Onset latencies. Cumulative distributions of visually evoked onset
response latencies in the LGNd, striate, and extrastriate areas as labeled.
The percentiles of cells that have begun to respond are plotted as a
function of time from stimulus presentation. <a href="/books/NBK11524/figure/ch31visualcortex.F24/?report=objectonly" target="object" rid-ob="figobch31visualcortexF24">(more...)</a></p></div></div><p>In general, M-stream areas respond rapidly and concurrently, whereas their
P-stream counterparts respond slowly and sequentially. Particularly relevant to
this review, the LGNd M cells become active 15 to 20 msec faster than do their
P-cell counterparts (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.83">83</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.84">84</a>),
and this temporal separation is maintained in the geniculorecipient layers
4C&#x003b1; and 4C&#x003b2; (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.80">80</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.82">82</a>, <a class="bk_pop" href="#ch31visualcortex.EXTYLES.83">83</a>).
Thus, a functional separation in response timing exists in the M and P pathways
of the subcortex and V1 and appears to be conveyed to the dorsal and ventral
streams of the extrastriate cortex.</p></div><div id="ch31visualcortex.Illusory_Contour_Per"><h3>Illusory Contour Perception</h3><p>The modern view of visual perception is one of dynamic processes that go beyond
the simple replication of visual information provided to the retina. For over 80
years, Gestalt psychologists have argued that the act of perception creates a
Gestalt, a figure or form that is not a property of an object observed but
represents the organization of sensations by the brain (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.85">85</a>). This dynamism is thought to be
crucial for the performance of simple, everyday visual tasks, such as the
recognition of an object that is partially occluded. Thus, the study of how the
brain is capable of filling in the missing pieces is an important topic; one
that has most often been carried out through the use of "illusory contours".</p><p>Illusory contours (ICs) are defined by their subjective appearance in the
absensce of any luminance differences in the image itself. A classic example of
an IC is the illusory square, where four sectored discs oriented in an
appropriate manner generate the percept of a square. In this instance, it is
clear that no true luminance differences exist to form a complete square, and
yet a square is perceived (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F25/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF25" rid-ob="figobch31visualcortexF25">Fig. 25</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF25" co-legend-rid="figlgndch31visualcortexF25"><a href="/books/NBK11524/figure/ch31visualcortex.F25/?report=objectonly" target="object" title="Figure 25" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF25" rid-ob="figobch31visualcortexF25"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf25.gif" src-large="/books/NBK11524/bin/visualcortexf25.jpg" alt="Figure 25. Illusory contours as seen in the illusory square." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF25"><h4 id="ch31visualcortex.F25"><a href="/books/NBK11524/figure/ch31visualcortex.F25/?report=objectonly" target="object" rid-ob="figobch31visualcortexF25">Figure 25</a></h4><p class="float-caption no_bottom_margin">Illusory contours as seen in the illusory square. </p></div></div><p>Behavioral tests indicate that cats and monkeys are capable of perceiving such
contours (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.86">86-88</a>).
Recent physiological studies have examined whether single cells in striate and
extrastriate cortex respond similarly to conventional luminance contours and
those defined by illusions (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.89">89-92</a>).
In each of these studies, IC-responsive cells were reported. However, these
studies provide conflicting evidence about the origin of IC responsivity,
arguing for or against the presence of IC-responding cells in V1. The use of
alternative ICs in the different studies confuses this issue further.</p><p>We sought to approach illusory contour perception from the broader issue of
contour perception in general (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.93">93</a>). The issue
here is how the brain encodes a stimulus boundary (e.g., a square) when the
visual cue that defines that boundary (e.g., color, luminance, texture, motion,
illusion, etc.) is varied. As Gestalt psychologists would note, the stimulus is
very different in each of these cases, but the fundamental percept, the square,
remains the same. We asked two fundamental questions. First, are there V1 or V2
cells in cat and monkey capable of responding in a similar fashion to a
boundary, regardless of the cue defining it? Alternatives to this include the
origin of cue invariance at later stages of visual processing or the separate
channeling of cue information via different subpopulations of cells, each
responsible for one cue. Second, if such cells exist, are they equally prevalent
in V1 and V2? Our results demonstrated that a subpopulation of cells in both
regions can respond to a stimulus boundary, such as an oriented bar, in a
cue-invariant manner, although this property was rare in V1 while prevalent in
V2 (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F26/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF26" rid-ob="figobch31visualcortexF26">Fig. 26</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF26" co-legend-rid="figlgndch31visualcortexF26"><a href="/books/NBK11524/figure/ch31visualcortex.F26/?report=objectonly" target="object" title="Figure 26" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF26" rid-ob="figobch31visualcortexF26"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf26.gif" src-large="/books/NBK11524/bin/visualcortexf26.jpg" alt="Figure 26. Example of a cue-invariant cell in cat area 18." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF26"><h4 id="ch31visualcortex.F26"><a href="/books/NBK11524/figure/ch31visualcortex.F26/?report=objectonly" target="object" rid-ob="figobch31visualcortexF26">Figure 26</a></h4><p class="float-caption no_bottom_margin">Example of a cue-invariant cell in cat area 18. This cell responds
with the same degree of orientation bias and to the same preferred
orientation, regardless of whether the bar is defined by simple luminance
(top), texture (middle), or isoluminant gratings <a href="/books/NBK11524/figure/ch31visualcortex.F26/?report=objectonly" target="object" rid-ob="figobch31visualcortexF26">(more...)</a></p></div></div><p>One conclusion from this work is that cells in the very first stage of cortical
processing are already capable of responding to a single stimulus boundary in a
complex manner that allows for object detection, even as the cues defining the
object change or are partially occluded (<a class="bk_pop" href="#ch31visualcortex.EXTYLES.93">93</a>).</p></div><div id="ch31visualcortex.Understanding_Vision"><h3>Understanding Vision: A Problem of Reverse Engineering</h3><p>Our attempt to understand the visual pathways is very much like approaching a
machine about which we know nothing but its basic functions. By way of analogy,
we all know how to operate a car (more or less) and recognize its basic
function&#x02014;to get us from one place to another. Now let us assume that
we knew absolutely nothing but this and, for some reason, decided we should
learn every detail of the car's inner workings. We might start by trying to
figure out the parts of the car devoted to this central function and those that
are not. We remove the bumper, horn, AC, and windshields and find that the car
still runs splendidly. We remove small parts of the engine, piece by piece until
the car no longer starts, analogous to the lesion studies in the brain. Slowly,
we begin to understand what parts of the car (brain) are involved in locomotion
(vision). In vision research, we are very much at this stage of the game, still
wanting to know what each part actually does, when it does it, and how all the
individual parts act in concert. It is the hope of many researchers, myself
included, that a careful investigation into the structure and function of the
visual pathways using chemical, electrophysiological, genetic, and behavioral
approaches will culminate in a true understanding of how the brain provides us
with this most crucial of sensory capabilities, vision (<a class="figpopup" href="/books/NBK11524/figure/ch31visualcortex.F27/?report=objectonly" target="object" rid-figpopup="figch31visualcortexF27" rid-ob="figobch31visualcortexF27">Fig.
27</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch31visualcortexF27" co-legend-rid="figlgndch31visualcortexF27"><a href="/books/NBK11524/figure/ch31visualcortex.F27/?report=objectonly" target="object" title="Figure 27" class="img_link icnblk_img figpopup" rid-figpopup="figch31visualcortexF27" rid-ob="figobch31visualcortexF27"><img class="small-thumb" src="/books/NBK11524/bin/visualcortexf27.gif" src-large="/books/NBK11524/bin/visualcortexf27.jpg" alt="Figure 27. Reverse engineering: the brain studying the brain." /></a><div class="icnblk_cntnt" id="figlgndch31visualcortexF27"><h4 id="ch31visualcortex.F27"><a href="/books/NBK11524/figure/ch31visualcortex.F27/?report=objectonly" target="object" rid-ob="figobch31visualcortexF27">Figure 27</a></h4><p class="float-caption no_bottom_margin">Reverse engineering: the brain studying the brain. </p></div></div></div></div><div id="ch31visualcortex.Under_Construction"><h2 id="_ch31visualcortex_Under_Construction_">Under Construction</h2><p>Additional sections dealing with RF properties are under construction: They include:
1) ON/OFF RF subunit composition; 2) transient <i>versus</i> sustained
responsivity; 3) spatial and temporal frequency; 4) contrast sensitivity; and 5)
color selectivity.</p></div><div id="ch31visualcortex.AFN1"><h2 id="_ch31visualcortex_AFN1_">About the Author</h2><p>
<div class="graphic"><img src="/books/NBK11524/bin/visualcortexfu1.jpg" alt="Image visualcortexfu1.jpg" /></div>
Dr. Matthew Schmolesky was born in West Palm Beach, Florida.
He received his B.A. in Psychology and Philosophy from Furman University,
Greenville, South Carolina in 1993. He received his Masters in Experimental
Psychology from Wake Forest University in 1995 and his Ph.D. in Neuroscience
from the University of Utah in 2000, respectively. While studying at the
University of Utah, he conducted research on the visual pathways in cat and
monkey with Dr. Audie Leventhal, looking at aspects of color, orientation,
and aging. He recently completed a Grass Fellowship at the Marine Biological
Laboratory in Woods Hole, MA. Matt is currently a Research Fellow at Erasmus
University Rotterdam in the Netherlands, where he is studying synaptic
plasticity in the cerebellum at the cellular and behavioral levels.</p></div><div id="ch31visualcortex.References"><h2 id="_ch31visualcortex_References_">References</h2><dl class="temp-labeled-list"><dt>1.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.1">Polyak S. Chicago: University of Chicago Press; <span><span class="ref-journal">The vertebrate visual system. </span>1957</span></div></dd><dt>2.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.2">Carl Weigert (1845-1904). <span><span class="ref-journal">JAMA. </span>1964;<span class="ref-vol">189</span>:769–770.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/14174058" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 14174058</span></a>]</div></dd><dt>3.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.3">Franz Nissl (1860-1919), neuropathologist. <span><span class="ref-journal">JAMA. </span>1968;<span class="ref-vol">205</span>:460–461.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/4873492" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 4873492</span></a>]</div></dd><dt>4.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.4">Cajal SR. La retine des vertebres. In: Thorpe SA,
Glickstein M, translators. The structure of the retina. Springfield (IL):
Charles C. Thomas Publisher; 1933.</div></dd><dt>5.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.5">Fritsch G, Hitzig E. Ueber die elektrische Erregbarkeit des Grosshirns. On the
electrical excitability of the cerebrum. <span><span class="ref-journal">Archiv fur Anatomie, Physiologie und wissenschaftliche Medizin. </span>1870;<span class="ref-vol">37</span>:300–332.</span></div></dd><dt>6.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.6">Penfield W, Boldrey E. Somatic motor and sensory representation in the cerebral cortex
of man as studied by electrical stimulation. <span><span class="ref-journal">Brain. </span>1937;<span class="ref-vol">60</span>:389–443.</span></div></dd><dt>7.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.7">Daniel PM, Whitteridge D. The representation of the visual field on the calcarine cortex in
baboons and monkeys. <span><span class="ref-journal">J Physiol. </span>1959;<span class="ref-vol">148</span>:33P.</span> [<a href="/pmc/articles/PMC1359500/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC1359500</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/13883391" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 13883391</span></a>]</div></dd><dt>8.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.8">Talbot SA, Marshall WH. Physiological studies on neural mechanisms of visual localization
and discrimination. <span><span class="ref-journal">Am J Ophthal. </span>1941;<span class="ref-vol">24</span>:1255–1263.</span></div></dd><dt>9.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.9">Thompson JM, Woolsey CN, Talbot SA. Visual areas I and II of cerebral cortex of
rabbit. <span><span class="ref-journal">J Neurophysiol. </span>1950;<span class="ref-vol">13</span>:277–288.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/15422390" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 15422390</span></a>]</div></dd><dt>10.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.10">Hartline HK. The response of single optic nerve fibers of the vertebrate eye
to the illumination of the retina. <span><span class="ref-journal">Am J Physiol. </span>1938;<span class="ref-vol">121</span>:400–415.</span></div></dd><dt>11.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.11">Kuffler SW. Discharge patterns and functional organization of mammalian
retina. <span><span class="ref-journal">J Neurophysiol. </span>1953;<span class="ref-vol">16</span>:37–68.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/13035466" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 13035466</span></a>]</div></dd><dt>12.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.12">Mountcastle VB. Modality and topographic properties of single neurons of cat's
somatic sensory cortex. <span><span class="ref-journal">J Neurophysiol. </span>1957;<span class="ref-vol">20</span>:408–434.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/13439410" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 13439410</span></a>]</div></dd><dt>13.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.13">Powell TP, Mountcastle VB. Some aspects of the functional organization of the cortex of the
postcentral gyrus of the monkey: a correlation of findings obtained in a
single unit analysis with cytoarchitecture. <span><span class="ref-journal">Bull Johns Hopkins Hosp. </span>1959;<span class="ref-vol">105</span>:133–162.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/14434571" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 14434571</span></a>]</div></dd><dt>14.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.14">Hubel DH, Wiesel TN. Receptive fields of single neurones in the cat's striate
cortex. <span><span class="ref-journal">J Physiol. </span>1959;<span class="ref-vol">150</span>:91–104.</span> [<a href="/pmc/articles/PMC1363130/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC1363130</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/14403679" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 14403679</span></a>]</div></dd><dt>15.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.15">Hubel DH, Wiesel TN. Receptive fields, binocular interaction and functional
architecture in the cat's visual cortex. <span><span class="ref-journal">J Physiol. </span>1962;<span class="ref-vol">160</span>:106–154.</span> [<a href="/pmc/articles/PMC1359523/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC1359523</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/14449617" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 14449617</span></a>]</div></dd><dt>16.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.16">Hubel DH, Wiesel TN. Receptive fields and functional architecture of the monkey
striate cortex. <span><span class="ref-journal">J Physiol. </span>1968;<span class="ref-vol">195</span>:215–243.</span> [<a href="/pmc/articles/PMC1557912/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC1557912</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/4966457" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 4966457</span></a>]</div></dd><dt>17.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.17">Hubel DH, Wiesel TN. Sequence regularity and geometry of orientation columns in the
monkey striate cortex. <span><span class="ref-journal">J Comp Neurol. </span>1974;<span class="ref-vol">158</span>:267–293.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/4436456" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 4436456</span></a>]</div></dd><dt>18.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.18">Hubel DH, Wiesel TN, Stryker MP. Orientation columns in macaque monkey visual cortex demonstrated
by the 2-deoxyglucose autoradiographic technique. <span><span class="ref-journal">Nature. </span>1977;<span class="ref-vol">269</span>:328–330.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/409953" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 409953</span></a>]</div></dd><dt>19.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.19">Hubel DH. Exploration of the primary visual cortex,
1955&#x02013;78. <span><span class="ref-journal">Nature. </span>1982;<span class="ref-vol">299</span>:515–524.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/6750409" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 6750409</span></a>]</div></dd><dt>20.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.20">O'Kusky J, Colonnier M. A laminar analysis of the number of neurons, glia, and synapses
in the visual cortex (area 17) of adult macaque monkeys. <span><span class="ref-journal">J Comp Neurol. </span>1982;<span class="ref-vol">210</span>:278–290.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/7142443" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 7142443</span></a>]</div></dd><dt>21.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.21">Fitzpatrick D, Lund JS, Schmechel DE, Towles AC. Distribution of GABAergic neurons and axon terminals in the
macaque striate cortex. <span><span class="ref-journal">J Comp Neurol. </span>1987;<span class="ref-vol">264</span>:73–91.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/3680625" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 3680625</span></a>]</div></dd><dt>22.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.22">Peters A, Sethares C. Organization of pyramidal neruons in rhesus monkey primary visual
cortex. <span><span class="ref-journal">J Comp Neurol. </span>1991;<span class="ref-vol">306</span>:1–23.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/1710236" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 1710236</span></a>]</div></dd><dt>23.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.23">DeFelipe J, Hendry SHC, Hashikawa T, Molinari M, Jones EG. A microcolumnar structure of monkey cerebral cortex revealed by
immunocytochemical studies of double bouquet cell axons. <span><span class="ref-journal">Neuroscience. </span>1990;<span class="ref-vol">37</span>:655–673.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/1701039" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 1701039</span></a>]</div></dd><dt>24.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.24">DeFelipe J, Hendry SH, Jones EG. A correlative electron microscopic study of basket cells and
large GABAergic neurons in the monkey sensory-motor cortex. <span><span class="ref-journal">Neuroscience. </span>1986;<span class="ref-vol">17</span>:991–1009.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/2423922" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 2423922</span></a>]</div></dd><dt>25.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.25">Somogyi P, Kisvarday ZF, Martin KA, Whitteridge D. Synaptic connections of morphologically identified and
physiologically characterized large basket cells in the striate cortex of
cat. <span><span class="ref-journal">Neuroscience. </span>1983;<span class="ref-vol">10</span>:261–294.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/6633861" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 6633861</span></a>]</div></dd><dt>26.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.26">Lund JS. Local circuit neurons of macaque moniey striate cortex. I.
Neurons of laminae 4C and 5A. <span><span class="ref-journal">J Comp Neurol. </span>1987;<span class="ref-vol">257</span>:60–92.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/3571519" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 3571519</span></a>]</div></dd><dt>27.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.27">Lund JS, Hawken MJ, Parker AJ. Local circuit neurons of macaque moniey striate cortex. II.
Neurons of laminae 5B and 6. <span><span class="ref-journal">J Comp Neurol. </span>1988;<span class="ref-vol">276</span>:1–29.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/2461395" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 2461395</span></a>]</div></dd><dt>28.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.28">Lund JS, Yoshioka T. Local circuit neurons of macaque moniey striate cortex. III.
Neurons of laminae 4B, 4A, and 3B. <span><span class="ref-journal">J Comp Neurol. </span>1991;<span class="ref-vol">311</span>:234–258.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/1721632" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 1721632</span></a>]</div></dd><dt>29.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.29">Lund JS, Wu CQ. Local circuit neurons of macaque moniey striate cortex. IV.
Neurons of laminae 1&#x02013;3A. <span><span class="ref-journal">J Comp Neurol. </span>1997;<span class="ref-vol">384</span>:109–126.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/9214543" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 9214543</span></a>]</div></dd><dt>30.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.30">Fitzpatrick D, Itoh K, Diamond IT. The laminar organization of the lateral geniculate body and the
striate cortex in the squirrel monkey (Saimiri sciureus). <span><span class="ref-journal">J Neurosci. </span>1983;<span class="ref-vol">3</span>:673–702.</span> [<a href="/pmc/articles/PMC6564461/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC6564461</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/6187901" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 6187901</span></a>]</div></dd><dt>31.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.31">Lachica EA, Casagrande VA. Direct W-like geniculate projections to the cytochrome-oxidase
(CO) blobs in primate visual cortex: axon morphology. <span><span class="ref-journal">J Comp Neurol. </span>1992;<span class="ref-vol">319</span>:141–158.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/1375606" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 1375606</span></a>]</div></dd><dt>32.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.32">Fries W, Distel H. Large layer V1 neurons of monkey striate cortex (Meynert cells)
project to the superior colliculus. <span><span class="ref-journal">Proc R Soc Lond B Biol Sci. </span>1983;<span class="ref-vol">219</span>:53–59.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/6137827" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 6137827</span></a>]</div></dd><dt>33.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.33">Blasdel GG, Lund JS. Termination of afferent axons in macaque striate
cortex. <span><span class="ref-journal">J Neurosci. </span>1983;<span class="ref-vol">3</span>:1389–1413.</span> [<a href="/pmc/articles/PMC6564440/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC6564440</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/6864254" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 6864254</span></a>]</div></dd><dt>34.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.34">Hubel DH, Wiesel TN. Laminar and columnar distribution of geniculo-cortical fibers in
the macaque monkey. <span><span class="ref-journal">J Comp Neurol. </span>1972;<span class="ref-vol">146</span>:421–450.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/4117368" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 4117368</span></a>]</div></dd><dt>35.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.35">Lund JS. Organization of neurons in the visual cortex, area 17, of the
monkey (Macaca mulatta). <span><span class="ref-journal">J Comp Neurol. </span>1973;<span class="ref-vol">147</span>:455–496.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/4122705" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 4122705</span></a>]</div></dd><dt>36.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.36">Blasdel GG, Fitzpatrick D. Physiological organization of layer 4 in the macaque striate
cortex. <span><span class="ref-journal">J Neurosci. </span>1984;<span class="ref-vol">4</span>:880–895.</span> [<a href="/pmc/articles/PMC6564839/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC6564839</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/6200586" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 6200586</span></a>]</div></dd><dt>37.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.37">Yabuta NH, Callaway EM. Functional streams and local connections of layer 4C neurons in
primary visual cortex of macaque monkey. <span><span class="ref-journal">J Neurosci. </span>1998a;<span class="ref-vol">18</span>:9489–9499.</span> [<a href="/pmc/articles/PMC6792868/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC6792868</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/9801386" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 9801386</span></a>]</div></dd><dt>38.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.38">Yabuta NH, Callaway EM. Cytochrome-oxidase blobs and intrinsic horizontal connections of
layer 2/3 pyramidal neurons in primate V1. <span><span class="ref-journal">Vis Neurosci. </span>1998b;<span class="ref-vol">15</span>:1007–1027.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/9839966" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 9839966</span></a>]</div></dd><dt>39.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.39">Lund JS, Boothe RG. Interlaminar connections and pyramidal neuron organization in the
visual cortex, area 17, of the macaque monkey. <span><span class="ref-journal">J Comp Neurol. </span>1975;<span class="ref-vol">159</span>:305–334.</span></div></dd><dt>40.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.40">Fries W, Keizer K, Kuypers HG. Large layer VI cells in macaque striate cortex (Meynert cells)
project to both superior colliculus and prestriate visual area
V5. <span><span class="ref-journal">Exp Brain Res. </span>1985;<span class="ref-vol">58</span>:613–616.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/3839191" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 3839191</span></a>]</div></dd><dt>41.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.41">Lund JS, Lund RD, Hendrickson AE, Bunt AH, Fuchs AF. The origin of efferent pathways from the primary visual cortex,
area 17, of the macaque monkey as shown by retrograde transport of
horseradish peroxidase. <span><span class="ref-journal">J Comp Neurol. </span>1975;<span class="ref-vol">164</span>:287–303.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/810501" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 810501</span></a>]</div></dd><dt>42.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.42">Hendrickson AE, Wilson JR, Ogren MP. The neuroanatomical organization of pathways between the dorsal
lateral geniculate nucleus and visual cortex in Old World and New World
primates. <span><span class="ref-journal">J Comp Neurol. </span>1978;<span class="ref-vol">182</span>:123–136.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/100530" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 100530</span></a>]</div></dd><dt>43.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.43">Hendry SH, Yoshioka T. A neurochemically distinct third channel in the macaque dorsal
lateral geniculate nucleus. <span><span class="ref-journal">Science. </span>1994;<span class="ref-vol">264</span>:575–577.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/8160015" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 8160015</span></a>]</div></dd><dt>44.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.44">Livingstone MS, Hubel DH. Thalamic inputs to cytochrome oxidase-rich regions in monkey
visual cortex. <span><span class="ref-journal">Proc Natl Acad Sci U S A. </span>1982;<span class="ref-vol">79</span>:6098–6101.</span> [<a href="/pmc/articles/PMC347060/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC347060</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/6193514" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 6193514</span></a>]</div></dd><dt>45.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.45">Boyd JD, Casagrande VA. Relationships between cytochrome oxidase (CO) blobs in primary
visual cortex (V1) and the distribution of neurons projecting to the middle
temporal area (MT). <span><span class="ref-journal">J Comp Neurol. </span>1999;<span class="ref-vol">409</span>:573–591.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/10376741" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 10376741</span></a>]</div></dd><dt>46.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.46">Shipp S, Zeki S. Segregation of pathways leading from area V2 to areas V4 and V5
of macaque monkey visual cortex. <span><span class="ref-journal">Nature. </span>1985;<span class="ref-vol">315</span>:322–325.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/2987702" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 2987702</span></a>]</div></dd><dt>47.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.47">Shipp S, Zeki S. The organization of connections between areas V5 and V1 in
macaque monkey visual cortex. <span><span class="ref-journal">Eur J Neurosci. </span>1989;<span class="ref-vol">1</span>:309–332.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/12106142" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 12106142</span></a>]</div></dd><dt>48.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.48">Shipp S, Zeki S. The organization of connections between areas V5 and V1 in
macaque monkey visual cortex. <span><span class="ref-journal">Eur J Neurosci. </span>1989;<span class="ref-vol">1</span>:333–354.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/12106143" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 12106143</span></a>]</div></dd><dt>49.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.49">Barone P, Batardiere A, Knoblauch K, Kennedy H. Laminar distribution of neurons in extrastriate areas projecting
to visual areas V1 and V4 correlates with the hierarchical rank and
indicates the operation of a distance rule. <span><span class="ref-journal">J Neurosci. </span>2000;<span class="ref-vol">20</span>:3263–3281.</span> [<a href="/pmc/articles/PMC6773101/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC6773101</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/10777791" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 10777791</span></a>]</div></dd><dt>50.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.50">Felleman DJ, Van Essen DC. Distributed hierarchical processing in the primate cerebral
cortex. <span><span class="ref-journal">Cereb Cortex. </span>1991;<span class="ref-vol">1</span>:1–47.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/1822724" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 1822724</span></a>]</div></dd><dt>51.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.51">Hilgetag CC, O'Neill MA, Young MP. Indeterminate organization of the visual system. <span><span class="ref-journal">Science. </span>1996;<span class="ref-vol">271</span>:776–777.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/8628990" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 8628990</span></a>]</div></dd><dt>52.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.52">Adams MM, Hof PR, Gattass R, Webster MJ, Ungerleider LG. Visual cortical projections and chemoarchitecture of macaque
monkey pulvinar. <span><span class="ref-journal">J Comp Neurol. </span>2000;<span class="ref-vol">419</span>:377–393.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/10723012" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 10723012</span></a>]</div></dd><dt>53.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.53">Doty RW. Nongeniculate afferents to striate cortex in
macaques. <span><span class="ref-journal">J Comp Neurol. </span>1983;<span class="ref-vol">218</span>:159–173.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/6886069" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 6886069</span></a>]</div></dd><dt>54.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.54">Graham J. Some topographical connections of the striate cortex with
subcortical structures in Macaca fascicularis. <span><span class="ref-journal">Exp Brain Res. </span>1982;<span class="ref-vol">47</span>:1–14.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/7117434" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 7117434</span></a>]</div></dd><dt>55.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.55">Ogren M, Hendrickson A. Pathways between striate cortex and subcortical regions in Macaca
mulatta and Saimiri sciureus: evidence for a reciprocal pulvinar
connection. <span><span class="ref-journal">Exp Neurol. </span>1976;<span class="ref-vol">53</span>:780–800.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/826404" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 826404</span></a>]</div></dd><dt>56.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.56">Rezak M, Benevento LA. A comparison of the organization of the projections of the dorsal
lateral geniculate nucleus, the inferior pulvinar and adjacent lateral
pulvinar to primary visual cortex (area 17) in the macaque
monkey. <span><span class="ref-journal">Brain Res. </span>1979;<span class="ref-vol">167</span>:19–40.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/88245" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 88245</span></a>]</div></dd><dt>57.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.57">Perkel DJ, Bullier J, Kennedy H. Topography of the afferent connectivity of area 17 in the macaque
monkey: a double-labelling study. <span><span class="ref-journal">J Comp Neurol. </span>1986;<span class="ref-vol">253</span>:374–402.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/3793996" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 3793996</span></a>]</div></dd><dt>58.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.58">Fitzpatrick D, Usrey WM, Schofield BR, Einstein G. The sublaminar organization of corticogeniculate neurons in layer
6 of macaque striate cortex. <span><span class="ref-journal">Vis Neurosci. </span>1994;<span class="ref-vol">11</span>:307–315.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/7516176" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 7516176</span></a>]</div></dd><dt>59.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.59">Livingstone MS, Hubel DH. Connections between layer 4B of area 17 and the thick cytochrome
oxidase stripes of area 18 in the squirrel monkey. <span><span class="ref-journal">J Neurosci. </span>1987;<span class="ref-vol">7</span>:3371–3377.</span> [<a href="/pmc/articles/PMC6569048/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC6569048</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/2824713" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 2824713</span></a>]</div></dd><dt>60.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.60">Maunsell JH, Van Essen DC. The connections of the middle temporal visual area (MT) and their
relationship to a cortical hierarchy in the macaque monkey. <span><span class="ref-journal">J Neurosci. </span>1983;<span class="ref-vol">3</span>:2563–2586.</span> [<a href="/pmc/articles/PMC6564662/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC6564662</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/6655500" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 6655500</span></a>]</div></dd><dt>61.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.61">Ungerleider LG, Desimone R. Projections to the superior temporal sulcus from the central and
peripheral field representations of V1 and V2. <span><span class="ref-journal">J Comp Neurol. </span>1986a;<span class="ref-vol">248</span>:147–163.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/3722456" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 3722456</span></a>]</div></dd><dt>62.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.62">Ungerleider LG, Desimone R. Cortical connections of visual area MT in the
macaque. <span><span class="ref-journal">J Comp Neurol. </span>1986b;<span class="ref-vol">248</span>:190–222.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/3722458" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 3722458</span></a>]</div></dd><dt>63.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.63">Boussaoud D, Ungerleider LG, Desimone R. Pathways for motion analysis: cortical connections of the medial
superior temporal and fundus of the superior temporal visual areas in the
macaque. <span><span class="ref-journal">J Comp Neurol. </span>1990;<span class="ref-vol">296</span>:462–495.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/2358548" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 2358548</span></a>]</div></dd><dt>64.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.64">Rockland KS, Saleem KS, Tanaka K. Divergent feedback connections from areas V4 and TEO in the
macaque. <span><span class="ref-journal">Vis Neurosci. </span>1994;<span class="ref-vol">11</span>:579–600.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/8038130" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 8038130</span></a>]</div></dd><dt>65.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.65">Suzuki W, Saleem KS, Tanaka K. Divergent backward projections from the anterior part of the
inferotemporal cortex (area TE) in the macaque. <span><span class="ref-journal">J Comp Neurol. </span>2000;<span class="ref-vol">422</span>:206–228.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/10842228" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 10842228</span></a>]</div></dd><dt>66.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.66">Fries W. Pontine projection from striate and prestriate visual cortex in
the macaque monkey: an anterograde study. <span><span class="ref-journal">Vis Neurosci. </span>1990;<span class="ref-vol">4</span>:205–216.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/2078502" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 2078502</span></a>]</div></dd><dt>67.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.67">Gutierrez C, Cusick CG. Area V1 in macaque monkeys projects to multiple histochemically
defined subdivisions of the inferior pulvinar complex. <span><span class="ref-journal">Brain Res. </span>1997;<span class="ref-vol">765</span>:349–356.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/9313911" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 9313911</span></a>]</div></dd><dt>68.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.68">Erwin E, Baker FH, Busen WF, Malpeli JG. Relationship between laminar topology and retinotopy in the
rhesus lateral geniculate nucleus: results from a functional
atlas. <span><span class="ref-journal">J Comp Neurol. </span>1999;<span class="ref-vol">407</span>:92–102.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/10213190" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 10213190</span></a>]</div></dd><dt>69.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.69">De Valois RL, Yund EW, Hepler N. The orientation and direction selectivity of cells in the macaque
visual cortex. <span><span class="ref-journal">Vision Res. </span>1982;<span class="ref-vol">22</span>:531–544.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/7112953" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 7112953</span></a>]</div></dd><dt>70.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.70">Schiller PH, Finlay BL, Volman SF. Quantitative studies of single-cell properties in monkey striate
cortex. I. Spatiotemporal organization of receptive fields. <span><span class="ref-journal">J Neurophysiol. </span>1976;<span class="ref-vol">39</span>:1288–1319.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/825621" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 825621</span></a>]</div></dd><dt>71.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.71">Bonhoeffer T, Grinvald A. Iso-orientation domains in cat visual cortex are arranged in
pinwheel-like patterns. <span><span class="ref-journal">Nature. </span>1991;<span class="ref-vol">353</span>:429–431.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/1896085" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 1896085</span></a>]</div></dd><dt>72.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.72">Livingstone MS. Mechanisms of direction selectivity in macaque V1. <span><span class="ref-journal">Neuron. </span>1998;<span class="ref-vol">20</span>:509–526.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/9539125" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 9539125</span></a>]</div></dd><dt>73.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.73">Ringach DL, Hawken MJ, Shapley R. Dynamics of orientation tuning in macaque primary visual
cortex. <span><span class="ref-journal">Nature. </span>1997;<span class="ref-vol">387</span>:281–284.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/9153392" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 9153392</span></a>]</div></dd><dt>74.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.74">DeAngelis GC, Cumming BG, Newsome WT. Cortical area MT and the perception of stereoscopic
depth. <span><span class="ref-journal">Nature. </span>1998;<span class="ref-vol">394</span>:677–680.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/9716130" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 9716130</span></a>]</div></dd><dt>75.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.75">DeAngelis GC, Newsome WT. Organization of disparity-selective neurons in macaque area
MT. <span><span class="ref-journal">J Neurosci. </span>1999;<span class="ref-vol">19</span>:1398–1415.</span> [<a href="/pmc/articles/PMC6786027/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC6786027</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/9952417" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 9952417</span></a>]</div></dd><dt>76.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.76">DeYoe EA, Felleman DJ, Van Essen DC, McClendon E. Multiple processing streams in occipitotemporal visual
cortex. <span><span class="ref-journal">Nature. </span>1994;<span class="ref-vol">371</span>:151–154.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/8072543" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 8072543</span></a>]</div></dd><dt>77.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.77">Van Essen DC, Newsome WT, Maunsell JH, Bixby JL. The projections from striate cortex (V1) to areas V2 and V3 in
the macaque monkey: asymmetries, areal boundaries, and patchy
connections. <span><span class="ref-journal">J Comp Neurol. </span>1986;<span class="ref-vol">244</span>:451–480.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/3958238" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 3958238</span></a>]</div></dd><dt>78.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.78">Essen DC, Van Anderson CH, Felleman DJ. Information processing in the primate visual system: an
integrated systems perspective. <span><span class="ref-journal">Science. </span>1992;<span class="ref-vol">255</span>:419–423.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/1734518" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 1734518</span></a>]</div></dd><dt>79.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.79">Nowak LG, Bullier J. The timing of information
transfer in the visual system. In: Kaas JH, Rockland K, Peters A, editors.
Cerebral cortex. New York: Plenum Press; 1998. p.
205&#x02013;241.</div></dd><dt>80.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.80">Maunsell JH, Gibson JR. Visual response latencies in striate cortex of the macaque
monkey. <span><span class="ref-journal">J Neurophysiol. </span>1992;<span class="ref-vol">68</span>:1332–1344.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/1432087" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 1432087</span></a>]</div></dd><dt>81.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.81">Thompson KG, Hanes DP, Bichot NP, Schall JD. Perceptual and motor processing stages identified in the activity
of macaque frontal eye field neurons during visual search. <span><span class="ref-journal">J Neurophysiol. </span>1996;<span class="ref-vol">76</span>:4040–4055.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/8985899" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 8985899</span></a>]</div></dd><dt>82.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.82">Nowak LG, Munk MH, Girard P, Bullier J. Visual latencies in areas V1 and V2 of the macaque
monkey. <span><span class="ref-journal">Vis Neurosci. </span>1995;<span class="ref-vol">12</span>:371–384.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/7786857" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 7786857</span></a>]</div></dd><dt>83.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.83">Schmolesky MT, Wang YC, Hanes DP, Thompson KG, Leutgeb S, Schall JD, Leventhal AG. Signal timing across the macaque visual system. <span><span class="ref-journal">J Neurophysiol. </span>1998;<span class="ref-vol">79</span>:3272–3278.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/9636126" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 9636126</span></a>]</div></dd><dt>84.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.84">Maunsell JH, Ghose GM, Assad JA, McAdams CJ, Boudreau CE, Noerager BD. Visual response latencies of magnocellular and parvocellular LGN
neurons in macaque monkeys. <span><span class="ref-journal">Vis Neurosci. </span>1999;<span class="ref-vol">16</span>:1–14.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/10022474" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 10022474</span></a>]</div></dd><dt>85.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.85">Kandel ER. Perception of motion, depth, and
form. In: Kandel ER, Schwartz JH, Jessel TM, editors. Principles of Neural
Science. Norwalk (CT): Appleton &#x00026; Lange; 1991.</div></dd><dt>86.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.86">Bravo M, Blake R, Morrison S. Cats see subjective contours. <span><span class="ref-journal">Vision Res. </span>1988;<span class="ref-vol">28</span>:861–865.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/3250081" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 3250081</span></a>]</div></dd><dt>87.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.87">De Weerd P, Vandenbussche E, De Bruyn B, Orban GA. Illusory contour orientation discrimination in the
cat. <span><span class="ref-journal">Behav Brain Res. </span>1990;<span class="ref-vol">39</span>:1–17.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/2390193" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 2390193</span></a>]</div></dd><dt>88.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.88">De Weerd P, Desimone R, Ungerleider LG. Cue-dependent deficits in grating orientation discrimination
after V4 lesions in macaques. <span><span class="ref-journal">Vis Neurosci. </span>1996;<span class="ref-vol">13</span>:529–538.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/8782380" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 8782380</span></a>]</div></dd><dt>89.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.89">Grosof DH, Shapley RM, Hawken MJ. Macaque V1 neurons can signal 'illusory' contours. <span><span class="ref-journal">Nature. </span>1993;<span class="ref-vol">365</span>:550–552.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/8413610" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 8413610</span></a>]</div></dd><dt>90.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.90">Peterhans E, von der Heydt R. Mechanisms of contour perception in monkey visual cortex. II.
Contours bridging gaps. <span><span class="ref-journal">J Neurosci. </span>1989;<span class="ref-vol">9</span>:1749–1763.</span> [<a href="/pmc/articles/PMC6569836/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC6569836</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/2723748" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 2723748</span></a>]</div></dd><dt>91.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.91">von der Heydt R, Peterhans E, Baumgartner G. Illusory contours and cortical neuron responses. <span><span class="ref-journal">Science. </span>1984;<span class="ref-vol">224</span>:1260–1262.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/6539501" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 6539501</span></a>]</div></dd><dt>92.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.92">von der Heydt R, Peterhans E. Mechanisms of contour perception in monkey visual cortex. I.
Lines of pattern discontinuity. <span><span class="ref-journal">J Neurosci. </span>1989;<span class="ref-vol">9</span>:1731–1748.</span> [<a href="/pmc/articles/PMC6569817/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC6569817</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/2723747" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 2723747</span></a>]</div></dd><dt>93.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.93">Leventhal AG, Wang Y-C, Schmolesky MT, Zhou Y. Neural correlates of boundary perception. <span><span class="ref-journal">Vis Neurosci. </span>1998;<span class="ref-vol">15</span>:1107–1118.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/9839975" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 9839975</span></a>]</div></dd><dt>94.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.94">Olavarria JF, Van Essen DC. The global pattern of cytochrome oxidase stripes in visual area
V2 of the macaque monkey. <span><span class="ref-journal">Cereb Cortex. </span>1997;<span class="ref-vol">7</span>:395–404.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/9261570" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 9261570</span></a>]</div></dd><dt>95.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.95">Schmolesky MT, Wang Y, Pu M, Leventhal AG. Degradation of stimulus selectivity of visual cortical cells in
senescent rhesus monkeys. <span><span class="ref-journal">Nat Neurosci. </span>2000;<span class="ref-vol">3</span>:384–390.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/10725929" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 10725929</span></a>]</div></dd><dt>96.</dt><dd><div class="bk_ref" id="ch31visualcortex.EXTYLES.96">Leventhal AG, Thompson KG, Liu D, Zhou Y, Ault SJ. Concomitant sensitivity to orientation, direction, and color of
cells in layers 2, 3, and 4 of monkey striate cortex. <span><span class="ref-journal">J Neurosci. </span>1995;<span class="ref-vol">15</span>:1808–1818.</span> [<a href="/pmc/articles/PMC6578154/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC6578154</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/7891136" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 7891136</span></a>]</div></dd></dl></div><div id="bk_toc_contnr"></div></div></div>
<div class="post-content"><div><div class="half_rhythm"><a href="/books/about/copyright/">Copyright</a>: © 2025 Webvision .<p class="small">All copyright for chapters belongs to the individual authors who created them. However, for non-commercial, academic purposes, images and content from the chapters portion of Webvision may be used with a non-exclusive rights under a Attribution, <a href="https://creativecommons.org/licenses/by-nc/4.0/" ref="pagearea=meta&amp;targetsite=external&amp;targetcat=link&amp;targettype=uri">Noncommercial 4.0 International (CC BY-NC) Creative Commons license</a>. Cite Webvision, http://webvision.med.utah.edu/ as the source. Commercial applications need to obtain license permission from the administrator of Webvision and are generally declined unless the copyright owner can/wants to donate or license material. Use online should be accompanied by a link back to the original source of the material. All imagery or content associated with blog posts belong to the authors of said posts, except where otherwise noted.</p></div><div class="small"><span class="label">Bookshelf ID: NBK11524</span><span class="label">PMID: <a href="https://pubmed.ncbi.nlm.nih.gov/21413385" title="PubMed record of this page" ref="pagearea=meta&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">21413385</a></span></div><div style="margin-top:2em" class="bk_noprnt"><a class="bk_cntns" href="/books/n/webvision/">Contents</a><div class="pagination bk_noprnt"><a class="active page_link prev" href="/books/n/webvision/brainvisual/" title="Previous page in this title">&lt; Prev</a><a class="active page_link next" href="/books/n/webvision/repair/" title="Next page in this title">Next &gt;</a></div></div></div></div>
</div>
<!-- Custom content below content -->
<div class="col4">
</div>
<!-- Book content -->
<!-- Custom contetnt below bottom nav -->
<div class="col5">
</div>
</div>
<div id="rightcolumn" class="four_col col last">
<!-- Custom content above discovery portlets -->
<div class="col6">
<div id="ncbi_share_book"><a href="#" class="ncbi_share" data-ncbi_share_config="popup:false,shorten:true" ref="id=NBK11524&amp;db=books">Share</a></div>
</div>
<div xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"></div><div class="portlet"><div class="portlet_head"><div class="portlet_title"><h3><span>Views</span></h3></div><a name="Shutter" sid="1" href="#" class="portlet_shutter" title="Show/hide content" remembercollapsed="true" pgsec_name="PDF_download" id="Shutter"></a></div><div class="portlet_content"><ul xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="simple-list"><li><a href="/books/NBK11524/?report=reader">PubReader</a></li><li><a href="/books/NBK11524/?report=printable">Print View</a></li><li><a data-jig="ncbidialog" href="#_ncbi_dlg_citbx_NBK11524" data-jigconfig="width:400,modal:true">Cite this Page</a><div id="_ncbi_dlg_citbx_NBK11524" style="display:none" title="Cite this Page"><div class="bk_tt">Schmolesky M. The Primary Visual Cortex. 2005 May 1 [Updated 2007 Jun 14]. In: Kolb H, Fernandez E, Jones B, et al., editors. Webvision: The Organization of the Retina and Visual System [Internet]. Salt Lake City (UT): University of Utah Health Sciences Center; 1995-. <span class="bk_cite_avail"></span></div></div></li><li><a href="/books/NBK11524/pdf/Bookshelf_NBK11524.pdf">PDF version of this page</a> (4.0M)</li><li><a href="/books/n/webvision/pdf/">PDF version of this title</a> (235M)</li></ul></div></div><div class="portlet"><div class="portlet_head"><div class="portlet_title"><h3><span>In this Page</span></h3></div><a name="Shutter" sid="1" href="#" class="portlet_shutter" title="Show/hide content" remembercollapsed="true" pgsec_name="page-toc" id="Shutter"></a></div><div class="portlet_content"><ul xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="simple-list"><li><a href="#ch31visualcortex.Introduction" ref="log$=inpage&amp;link_id=inpage">Introduction</a></li><li><a href="#ch31visualcortex.Historical_Perspecti" ref="log$=inpage&amp;link_id=inpage">Historical Perspective</a></li><li><a href="#ch31visualcortex.Which_Anatomical_Pat" ref="log$=inpage&amp;link_id=inpage">Which Anatomical Pathways Carry the Visual Signal?</a></li><li><a href="#ch31visualcortex.What_Information_Doe" ref="log$=inpage&amp;link_id=inpage">What Information Does the Visual Signal Carry?</a></li><li><a href="#ch31visualcortex.Under_Construction" ref="log$=inpage&amp;link_id=inpage">Under Construction</a></li><li><a href="#ch31visualcortex.AFN1" ref="log$=inpage&amp;link_id=inpage">About the Author</a></li><li><a href="#ch31visualcortex.References" ref="log$=inpage&amp;link_id=inpage">References</a></li></ul></div></div><div class="portlet"><div class="portlet_head"><div class="portlet_title"><h3><span>Related Items in Bookshelf</span></h3></div><a name="Shutter" sid="1" href="#" class="portlet_shutter" title="Show/hide content" remembercollapsed="true" pgsec_name="source-links" id="Shutter"></a></div><div class="portlet_content"><ul xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="simple-list"><li><a href="https://www.ncbi.nlm.nih.gov/books?term=%22reference%20works%22%5BResource%20Type%5D" ref="pagearea=source-links&amp;targetsite=external&amp;targetcat=link&amp;targettype=uri">All Reference Works</a></li><li><a href="https://www.ncbi.nlm.nih.gov/books?term=&quot;textbooks&quot;%5BResource%20Type%5D" ref="pagearea=source-links&amp;targetsite=external&amp;targetcat=link&amp;targettype=uri">All Textbooks</a></li></ul></div></div><div class="portlet"><div class="portlet_head"><div class="portlet_title"><h3><span>Related information</span></h3></div><a name="Shutter" sid="1" href="#" class="portlet_shutter" title="Show/hide content" remembercollapsed="true" pgsec_name="discovery_db_links" id="Shutter"></a></div><div class="portlet_content"><ul><li class="brieflinkpopper"><a class="brieflinkpopperctrl" href="/books/?Db=pmc&amp;DbFrom=books&amp;Cmd=Link&amp;LinkName=books_pmc_refs&amp;IdsFromResult=1651908" ref="log$=recordlinks">PMC</a><div class="brieflinkpop offscreen_noflow">PubMed Central citations</div></li><li class="brieflinkpopper"><a class="brieflinkpopperctrl" href="/books/?Db=pubmed&amp;DbFrom=books&amp;Cmd=Link&amp;LinkName=books_pubmed_refs&amp;IdsFromResult=1651908" ref="log$=recordlinks">PubMed</a><div class="brieflinkpop offscreen_noflow">Links to PubMed</div></li></ul></div></div><div class="portlet"><div class="portlet_head"><div class="portlet_title"><h3><span>Similar articles in PubMed</span></h3></div><a name="Shutter" sid="1" href="#" class="portlet_shutter" title="Show/hide content" remembercollapsed="true" pgsec_name="PBooksDiscovery_RA" id="Shutter"></a></div><div class="portlet_content"><ul><li class="brieflinkpopper two_line"><a class="brieflinkpopperctrl" href="/pubmed/36137063" ref="ordinalpos=1&amp;linkpos=1&amp;log$=relatedreviews&amp;logdbfrom=pubmed"><span xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="invert">Review</span> Depressing time: Waiting, melancholia, and the psychoanalytic practice of care.</a><span class="source">[The Time of Anthropology: Stud...]</span><div class="brieflinkpop offscreen_noflow"><span xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="invert">Review</span> Depressing time: Waiting, melancholia, and the psychoanalytic practice of care.<div class="brieflinkpopdesc"><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="author">Salisbury L, Baraitser L. </em><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="cit">The Time of Anthropology: Studies of Contemporary Chronopolitics. 2020</em></div></div></li><li class="brieflinkpopper two_line"><a class="brieflinkpopperctrl" href="/pubmed/38116050" ref="ordinalpos=1&amp;linkpos=2&amp;log$=relatedarticles&amp;logdbfrom=pubmed">"I've Spent My Whole Life Striving to Be Normal": Internalized Stigma and Perceived Impact of Diagnosis in Autistic Adults.</a><span class="source">[Autism Adulthood. 2023]</span><div class="brieflinkpop offscreen_noflow">"I've Spent My Whole Life Striving to Be Normal": Internalized Stigma and Perceived Impact of Diagnosis in Autistic Adults.<div class="brieflinkpopdesc"><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="author">Huang Y, Trollor JN, Foley KR, Arnold SRC. </em><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="cit">Autism Adulthood. 2023 Dec 1; 5(4):423-436. Epub 2023 Dec 12.</em></div></div></li><li class="brieflinkpopper two_line"><a class="brieflinkpopperctrl" href="/pubmed/33934362" ref="ordinalpos=1&amp;linkpos=3&amp;log$=relatedarticles&amp;logdbfrom=pubmed">Australia in 2030: what is our path to health for all?</a><span class="source">[Med J Aust. 2021]</span><div class="brieflinkpop offscreen_noflow">Australia in 2030: what is our path to health for all?<div class="brieflinkpopdesc"><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="author">Backholer K, Baum F, Finlay SM, Friel S, Giles-Corti B, Jones A, Patrick R, Shill J, Townsend B, Armstrong F, et al. </em><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="cit">Med J Aust. 2021 May; 214 Suppl 8:S5-S40. </em></div></div></li><li class="brieflinkpopper two_line"><a class="brieflinkpopperctrl" href="/pubmed/38116059" ref="ordinalpos=1&amp;linkpos=4&amp;log$=relatedarticles&amp;logdbfrom=pubmed">Using Experience Sampling Methodology to Capture Disclosure Opportunities for Autistic Adults.</a><span class="source">[Autism Adulthood. 2023]</span><div class="brieflinkpop offscreen_noflow">Using Experience Sampling Methodology to Capture Disclosure Opportunities for Autistic Adults.<div class="brieflinkpopdesc"><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="author">Love AMA, Edwards C, Cai RY, Gibbs V. </em><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="cit">Autism Adulthood. 2023 Dec 1; 5(4):389-400. Epub 2023 Dec 12.</em></div></div></li><li class="brieflinkpopper two_line"><a class="brieflinkpopperctrl" href="/pubmed/38686101" ref="ordinalpos=1&amp;linkpos=5&amp;log$=relatedreviews&amp;logdbfrom=pubmed"><span xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="invert">Review</span> Mapping the scientific knowledge and approaches to defining and measuring hate crime, hate speech, and hate incidents: A systematic review.</a><span class="source">[Campbell Syst Rev. 2024]</span><div class="brieflinkpop offscreen_noflow"><span xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="invert">Review</span> Mapping the scientific knowledge and approaches to defining and measuring hate crime, hate speech, and hate incidents: A systematic review.<div class="brieflinkpopdesc"><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="author">Vergani M, Perry B, Freilich J, Chermak S, Scrivens R, Link R, Kleinsman D, Betts J, Iqbal M. </em><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="cit">Campbell Syst Rev. 2024 Jun; 20(2):e1397. Epub 2024 Apr 28.</em></div></div></li></ul><a class="seemore" href="/sites/entrez?db=pubmed&amp;cmd=link&amp;linkname=pubmed_pubmed_reviews&amp;uid=21413385" ref="ordinalpos=1&amp;log$=relatedreviews_seeall&amp;logdbfrom=pubmed">See reviews...</a><a class="seemore" href="/sites/entrez?db=pubmed&amp;cmd=link&amp;linkname=pubmed_pubmed&amp;uid=21413385" ref="ordinalpos=1&amp;log$=relatedarticles_seeall&amp;logdbfrom=pubmed">See all...</a></div></div><div class="portlet"><div class="portlet_head"><div class="portlet_title"><h3><span>Recent Activity</span></h3></div><a name="Shutter" sid="1" href="#" class="portlet_shutter" title="Show/hide content" remembercollapsed="true" pgsec_name="recent_activity" id="Shutter"></a></div><div class="portlet_content"><div xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" id="HTDisplay" class=""><div class="action"><a href="javascript:historyDisplayState('ClearHT')">Clear</a><a href="javascript:historyDisplayState('HTOff')" class="HTOn">Turn Off</a><a href="javascript:historyDisplayState('HTOn')" class="HTOff">Turn On</a></div><ul id="activity"><li class="ra_rcd ralinkpopper two_line"><a class="htb ralinkpopperctrl" ref="log$=activity&amp;linkpos=1" href="/portal/utils/pageresolver.fcgi?recordid=67c9a766b15b832ebc79cd9b">The Primary Visual Cortex - Webvision</a><div class="ralinkpop offscreen_noflow">The Primary Visual Cortex - Webvision<div class="brieflinkpopdesc"></div></div><div class="tertiary"></div></li><li class="ra_rcd ralinkpopper two_line"><a class="htb ralinkpopperctrl" ref="log$=activity&amp;linkpos=2" href="/portal/utils/pageresolver.fcgi?recordid=67c9a762a68b6b5afcdf357d">Part IX: Brain Visual Areas - Webvision</a><div class="ralinkpop offscreen_noflow">Part IX: Brain Visual Areas - Webvision<div class="brieflinkpopdesc"></div></div><div class="tertiary"></div></li><li class="ra_rcd ralinkpopper two_line"><a class="htb ralinkpopperctrl" ref="log$=activity&amp;linkpos=3" href="/portal/utils/pageresolver.fcgi?recordid=67c9a761b15b832ebc79a0d4">The Perception of Depth - Webvision</a><div class="ralinkpop offscreen_noflow">The Perception of Depth - Webvision<div class="brieflinkpopdesc"></div></div><div class="tertiary"></div></li><li class="ra_rcd ralinkpopper two_line"><a class="htb ralinkpopperctrl" ref="log$=activity&amp;linkpos=4" href="/portal/utils/pageresolver.fcgi?recordid=67c9a76084f3725e59a72449">The Perception of Space - Webvision</a><div class="ralinkpop offscreen_noflow">The Perception of Space - Webvision<div class="brieflinkpopdesc"></div></div><div class="tertiary"></div></li><li class="ra_rcd ralinkpopper two_line"><a class="htb ralinkpopperctrl" ref="log$=activity&amp;linkpos=5" href="/portal/utils/pageresolver.fcgi?recordid=67c9a75fa68b6b5afcdf21a1">The Perception of Color - Webvision</a><div class="ralinkpop offscreen_noflow">The Perception of Color - Webvision<div class="brieflinkpopdesc"></div></div><div class="tertiary"></div></li></ul><p class="HTOn">Your browsing activity is empty.</p><p class="HTOff">Activity recording is turned off.</p><p id="turnOn" class="HTOff"><a href="javascript:historyDisplayState('HTOn')">Turn recording back on</a></p><a class="seemore" href="/sites/myncbi/recentactivity">See more...</a></div></div></div>
<!-- Custom content below discovery portlets -->
<div class="col7">
</div>
</div>
</div>
<!-- Custom content after all -->
<div class="col8">
</div>
<div class="col9">
</div>
<script type="text/javascript" src="/corehtml/pmc/js/jquery.scrollTo-1.4.2.js"></script>
<script type="text/javascript">
(function($){
$('.skiplink').each(function(i, item){
var href = $($(item).attr('href'));
href.attr('tabindex', '-1').addClass('skiptarget'); // ensure the target can receive focus
$(item).on('click', function(event){
event.preventDefault();
$.scrollTo(href, 0, {
onAfter: function(){
href.focus();
}
});
});
});
})(jQuery);
</script>
</div>
<div class="bottom">
<div id="NCBIFooter_dynamic">
<!--<component id="Breadcrumbs" label="breadcrumbs"/>
<component id="Breadcrumbs" label="helpdesk"/>-->
</div>
<div class="footer" id="footer">
<section class="icon-section">
<div id="icon-section-header" class="icon-section_header">Follow NCBI</div>
<div class="grid-container container">
<div class="icon-section_container">
<a class="footer-icon" id="footer_twitter" href="https://twitter.com/ncbi" aria-label="Twitter"><svg xmlns="http://www.w3.org/2000/svg" data-name="Layer 1" viewBox="0 0 300 300">
<defs>
<style>
.cls-11 {
fill: #737373;
}
</style>
</defs>
<title>Twitter</title>
<path class="cls-11" d="M250.11,105.48c-7,3.14-13,3.25-19.27.14,8.12-4.86,8.49-8.27,11.43-17.46a78.8,78.8,0,0,1-25,9.55,39.35,39.35,0,0,0-67,35.85,111.6,111.6,0,0,1-81-41.08A39.37,39.37,0,0,0,81.47,145a39.08,39.08,0,0,1-17.8-4.92c0,.17,0,.33,0,.5a39.32,39.32,0,0,0,31.53,38.54,39.26,39.26,0,0,1-17.75.68,39.37,39.37,0,0,0,36.72,27.3A79.07,79.07,0,0,1,56,223.34,111.31,111.31,0,0,0,116.22,241c72.3,0,111.83-59.9,111.83-111.84,0-1.71,0-3.4-.1-5.09C235.62,118.54,244.84,113.37,250.11,105.48Z">
</path>
</svg></a>
<a class="footer-icon" id="footer_facebook" href="https://www.facebook.com/ncbi.nlm" aria-label="Facebook"><svg xmlns="http://www.w3.org/2000/svg" data-name="Layer 1" viewBox="0 0 300 300">
<title>Facebook</title>
<path class="cls-11" d="M210.5,115.12H171.74V97.82c0-8.14,5.39-10,9.19-10h27.14V52l-39.32-.12c-35.66,0-42.42,26.68-42.42,43.77v19.48H99.09v36.32h27.24v109h45.41v-109h35Z">
</path>
</svg></a>
<a class="footer-icon" id="footer_linkedin" href="https://www.linkedin.com/company/ncbinlm" aria-label="LinkedIn"><svg xmlns="http://www.w3.org/2000/svg" data-name="Layer 1" viewBox="0 0 300 300">
<title>LinkedIn</title>
<path class="cls-11" d="M101.64,243.37H57.79v-114h43.85Zm-22-131.54h-.26c-13.25,0-21.82-10.36-21.82-21.76,0-11.65,8.84-21.15,22.33-21.15S101.7,78.72,102,90.38C102,101.77,93.4,111.83,79.63,111.83Zm100.93,52.61A17.54,17.54,0,0,0,163,182v61.39H119.18s.51-105.23,0-114H163v13a54.33,54.33,0,0,1,34.54-12.66c26,0,44.39,18.8,44.39,55.29v58.35H198.1V182A17.54,17.54,0,0,0,180.56,164.44Z">
</path>
</svg></a>
<a class="footer-icon" id="footer_github" href="https://github.com/ncbi" aria-label="GitHub"><svg xmlns="http://www.w3.org/2000/svg" data-name="Layer 1" viewBox="0 0 300 300">
<defs>
<style>
.cls-11,
.cls-12 {
fill: #737373;
}
.cls-11 {
fill-rule: evenodd;
}
</style>
</defs>
<title>GitHub</title>
<path class="cls-11" d="M151.36,47.28a105.76,105.76,0,0,0-33.43,206.1c5.28,1,7.22-2.3,7.22-5.09,0-2.52-.09-10.85-.14-19.69-29.42,6.4-35.63-12.48-35.63-12.48-4.81-12.22-11.74-15.47-11.74-15.47-9.59-6.56.73-6.43.73-6.43,10.61.75,16.21,10.9,16.21,10.9,9.43,16.17,24.73,11.49,30.77,8.79,1-6.83,3.69-11.5,6.71-14.14C108.57,197.1,83.88,188,83.88,147.51a40.92,40.92,0,0,1,10.9-28.39c-1.1-2.66-4.72-13.42,1-28,0,0,8.88-2.84,29.09,10.84a100.26,100.26,0,0,1,53,0C198,88.3,206.9,91.14,206.9,91.14c5.76,14.56,2.14,25.32,1,28a40.87,40.87,0,0,1,10.89,28.39c0,40.62-24.74,49.56-48.29,52.18,3.79,3.28,7.17,9.71,7.17,19.58,0,14.15-.12,25.54-.12,29,0,2.82,1.9,6.11,7.26,5.07A105.76,105.76,0,0,0,151.36,47.28Z">
</path>
<path class="cls-12" d="M85.66,199.12c-.23.52-1.06.68-1.81.32s-1.2-1.06-.95-1.59,1.06-.69,1.82-.33,1.21,1.07.94,1.6Zm-1.3-1">
</path>
<path class="cls-12" d="M90,203.89c-.51.47-1.49.25-2.16-.49a1.61,1.61,0,0,1-.31-2.19c.52-.47,1.47-.25,2.17.49s.82,1.72.3,2.19Zm-1-1.08">
</path>
<path class="cls-12" d="M94.12,210c-.65.46-1.71,0-2.37-.91s-.64-2.07,0-2.52,1.7,0,2.36.89.65,2.08,0,2.54Zm0,0"></path>
<path class="cls-12" d="M99.83,215.87c-.58.64-1.82.47-2.72-.41s-1.18-2.06-.6-2.7,1.83-.46,2.74.41,1.2,2.07.58,2.7Zm0,0">
</path>
<path class="cls-12" d="M107.71,219.29c-.26.82-1.45,1.2-2.64.85s-2-1.34-1.74-2.17,1.44-1.23,2.65-.85,2,1.32,1.73,2.17Zm0,0">
</path>
<path class="cls-12" d="M116.36,219.92c0,.87-1,1.59-2.24,1.61s-2.29-.68-2.3-1.54,1-1.59,2.26-1.61,2.28.67,2.28,1.54Zm0,0">
</path>
<path class="cls-12" d="M124.42,218.55c.15.85-.73,1.72-2,1.95s-2.37-.3-2.52-1.14.73-1.75,2-2,2.37.29,2.53,1.16Zm0,0"></path>
</svg></a>
<a class="footer-icon" id="footer_blog" href="https://ncbiinsights.ncbi.nlm.nih.gov/" aria-label="Blog">
<svg xmlns="http://www.w3.org/2000/svg" id="Layer_1" data-name="Layer 1" viewBox="0 0 40 40">
<defs><style>.cls-1{fill:#737373;}</style></defs>
<title>NCBI Insights Blog</title>
<path class="cls-1" d="M14,30a4,4,0,1,1-4-4,4,4,0,0,1,4,4Zm11,3A19,19,0,0,0,7.05,15a1,1,0,0,0-1,1v3a1,1,0,0,0,.93,1A14,14,0,0,1,20,33.07,1,1,0,0,0,21,34h3a1,1,0,0,0,1-1Zm9,0A28,28,0,0,0,7,6,1,1,0,0,0,6,7v3a1,1,0,0,0,1,1A23,23,0,0,1,29,33a1,1,0,0,0,1,1h3A1,1,0,0,0,34,33Z"></path>
</svg>
</a>
</div>
</div>
</section>
<section class="container-fluid bg-primary">
<div class="container pt-5">
<div class="row mt-3">
<div class="col-lg-3 col-12">
<p><a class="text-white" href="https://www.nlm.nih.gov/socialmedia/index.html">Connect with NLM</a></p>
<ul class="list-inline social_media">
<li class="list-inline-item"><a href="https://twitter.com/NLM_NIH" aria-label="Twitter" target="_blank" rel="noopener noreferrer"><svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" x="0px" y="0px" viewBox="0 0 249 249" style="enable-background:new 0 0 249 249;" xml:space="preserve">
<style type="text/css">
.st20 {
fill: #FFFFFF;
}
.st30 {
fill: none;
stroke: #FFFFFF;
stroke-width: 8;
stroke-miterlimit: 10;
}
</style>
<title>Twitter</title>
<g>
<g>
<g>
<path class="st20" d="M192.9,88.1c-5,2.2-9.2,2.3-13.6,0.1c5.7-3.4,6-5.8,8.1-12.3c-5.4,3.2-11.4,5.5-17.6,6.7 c-10.5-11.2-28.1-11.7-39.2-1.2c-7.2,6.8-10.2,16.9-8,26.5c-22.3-1.1-43.1-11.7-57.2-29C58,91.6,61.8,107.9,74,116 c-4.4-0.1-8.7-1.3-12.6-3.4c0,0.1,0,0.2,0,0.4c0,13.2,9.3,24.6,22.3,27.2c-4.1,1.1-8.4,1.3-12.5,0.5c3.6,11.3,14,19,25.9,19.3 c-11.6,9.1-26.4,13.2-41.1,11.5c12.7,8.1,27.4,12.5,42.5,12.5c51,0,78.9-42.2,78.9-78.9c0-1.2,0-2.4-0.1-3.6 C182.7,97.4,189.2,93.7,192.9,88.1z"></path>
</g>
</g>
<circle class="st30" cx="124.4" cy="128.8" r="108.2"></circle>
</g>
</svg></a></li>
<li class="list-inline-item"><a href="https://www.facebook.com/nationallibraryofmedicine" aria-label="Facebook" rel="noopener noreferrer" target="_blank">
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" x="0px" y="0px" viewBox="0 0 249 249" style="enable-background:new 0 0 249 249;" xml:space="preserve">
<style type="text/css">
.st10 {
fill: #FFFFFF;
}
.st110 {
fill: none;
stroke: #FFFFFF;
stroke-width: 8;
stroke-miterlimit: 10;
}
</style>
<title>Facebook</title>
<g>
<g>
<path class="st10" d="M159,99.1h-24V88.4c0-5,3.3-6.2,5.7-6.2h16.8V60l-24.4-0.1c-22.1,0-26.2,16.5-26.2,27.1v12.1H90v22.5h16.9 v67.5H135v-67.5h21.7L159,99.1z"></path>
</g>
</g>
<circle class="st110" cx="123.6" cy="123.2" r="108.2"></circle>
</svg>
</a></li>
<li class="list-inline-item"><a href="https://www.youtube.com/user/NLMNIH" aria-label="Youtube" target="_blank" rel="noopener noreferrer"><svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" x="0px" y="0px" viewBox="0 0 249 249" style="enable-background:new 0 0 249 249;" xml:space="preserve">
<title>Youtube</title>
<style type="text/css">
.st4 {
fill: none;
stroke: #FFFFFF;
stroke-width: 8;
stroke-miterlimit: 10;
}
.st5 {
fill: #FFFFFF;
}
</style>
<circle class="st4" cx="124.2" cy="123.4" r="108.2"></circle>
<g transform="translate(0,-952.36218)">
<path class="st5" d="M88.4,1037.4c-10.4,0-18.7,8.3-18.7,18.7v40.1c0,10.4,8.3,18.7,18.7,18.7h72.1c10.4,0,18.7-8.3,18.7-18.7 v-40.1c0-10.4-8.3-18.7-18.7-18.7H88.4z M115.2,1058.8l29.4,17.4l-29.4,17.4V1058.8z"></path>
</g>
</svg></a></li>
</ul>
</div>
<div class="col-lg-3 col-12">
<p class="address_footer text-white">National Library of Medicine<br />
<a href="https://www.google.com/maps/place/8600+Rockville+Pike,+Bethesda,+MD+20894/@38.9959508,-77.101021,17z/data=!3m1!4b1!4m5!3m4!1s0x89b7c95e25765ddb:0x19156f88b27635b8!8m2!3d38.9959508!4d-77.0988323" class="text-white" target="_blank" rel="noopener noreferrer">8600 Rockville Pike<br />
Bethesda, MD 20894</a></p>
</div>
<div class="col-lg-3 col-12 centered-lg">
<p><a href="https://www.nlm.nih.gov/web_policies.html" class="text-white">Web Policies</a><br />
<a href="https://www.nih.gov/institutes-nih/nih-office-director/office-communications-public-liaison/freedom-information-act-office" class="text-white">FOIA</a><br />
<a href="https://www.hhs.gov/vulnerability-disclosure-policy/index.html" class="text-white" id="vdp">HHS Vulnerability Disclosure</a></p>
</div>
<div class="col-lg-3 col-12 centered-lg">
<p><a class="supportLink text-white" href="https://support.nlm.nih.gov/">Help</a><br />
<a href="https://www.nlm.nih.gov/accessibility.html" class="text-white">Accessibility</a><br />
<a href="https://www.nlm.nih.gov/careers/careers.html" class="text-white">Careers</a></p>
</div>
</div>
<div class="row">
<div class="col-lg-12 centered-lg">
<nav class="bottom-links">
<ul class="mt-3">
<li>
<a class="text-white" href="//www.nlm.nih.gov/">NLM</a>
</li>
<li>
<a class="text-white" href="https://www.nih.gov/">NIH</a>
</li>
<li>
<a class="text-white" href="https://www.hhs.gov/">HHS</a>
</li>
<li>
<a class="text-white" href="https://www.usa.gov/">USA.gov</a>
</li>
</ul>
</nav>
</div>
</div>
</div>
</section>
<script type="text/javascript" src="/portal/portal3rc.fcgi/rlib/js/InstrumentOmnitureBaseJS/InstrumentNCBIConfigJS/InstrumentNCBIBaseJS/InstrumentPageStarterJS.js?v=1"> </script>
<script type="text/javascript" src="/portal/portal3rc.fcgi/static/js/hfjs2.js"> </script>
</div>
</div>
</div>
<!--/.page-->
</div>
<!--/.wrap-->
</div><!-- /.twelve_col -->
</div>
<!-- /.grid -->
<span class="PAFAppResources"></span>
<!-- BESelector tab -->
<noscript><img alt="statistics" src="/stat?jsdisabled=true&amp;ncbi_db=books&amp;ncbi_pdid=book-part&amp;ncbi_acc=NBK11524&amp;ncbi_domain=webvision&amp;ncbi_report=record&amp;ncbi_type=fulltext&amp;ncbi_objectid=&amp;ncbi_pcid=/NBK11524/&amp;ncbi_pagename=The Primary Visual Cortex - Webvision - NCBI Bookshelf&amp;ncbi_bookparttype=chapter&amp;ncbi_app=bookshelf" /></noscript>
<!-- usually for JS scripts at page bottom -->
<!--<component id="PageFixtures" label="styles"></component>-->
<!-- CE8B5AF87C7FFCB1_0191SID /projects/books/PBooks@9.11 portal106 v4.1.r689238 Tue, Oct 22 2024 16:10:51 -->
<span id="portal-csrf-token" style="display:none" data-token="CE8B5AF87C7FFCB1_0191SID"></span>
<script type="text/javascript" src="//static.pubmed.gov/portal/portal3rc.fcgi/4216699/js/3879255/4121861/3501987/4008961/3893018/3821238/4062932/4209313/4212053/4076480/3921943/3400083/3426610.js" snapshot="books"></script></body>
</html>
Reference in a new issue View git blame Copy permalink