Editing Visual cortex (section)

== V2 == <!--Please keep this header, as it is a redirect -->
{{Infobox anatomy
|Name = Colour centre
|Image= Constudproc.png
|Caption= The V-regions. More images in [[colour centre]]
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'''Visual area V2''', or '''secondary visual cortex''', also called '''prestriate cortex''',<ref>{{cite book | vauthors = Gazzaniga MS, Ivry RB, Mangun GR | date = 2002 | title = Cognitive Neuroscience: The Biology of the Mind | edition = 2nd | publisher = W W Norton & Co Inc | isbn = 978-0-393-97777-6 }}</ref> receives strong feedforward connections from V1 (direct and via the pulvinar) and sends robust connections to V3, V4, and V5. Additionally, it plays a crucial role in the integration and processing of visual information.

The feedforward connections from V1 to V2 contribute to the hierarchical processing of visual stimuli. V2 neurons build upon the basic features detected in V1, extracting more complex visual attributes such as texture, depth, and color. This hierarchical processing is essential for the construction of a more detailed representation of the visual scene.

Furthermore, the reciprocal feedback connections from V2 to V1 play a significant role in modulating the activity of V1 neurons. This feedback loop is thought to be involved in processes such as attention, perceptual grouping, and figure-ground segregation. The dynamic interplay between V1 and V2 highlights the intricate nature of information processing within the visual system.

Moreover, V2's connections with subsequent visual areas, including V3, V4, and V5, contribute to the formation of a distributed network for visual processing. These connections enable the integration of different visual features, such as motion and form, across multiple stages of the visual hierarchy.<ref>Taylor, Katherine. and Jeanette Rodriguez. "Visual Discrimination." StatPearls, StatPearls Publishing, 19 September 2022</ref>

In terms of anatomy, V2 is split into four quadrants, a [[Dorsum (biology)|dorsal]] and [[ventral]] representation in the left and the right [[cerebral hemisphere|hemispheres]]. Together, these four regions provide a complete map of the visual world. V2 has many properties in common with V1: Cells are tuned to simple properties such as orientation, spatial frequency, and color. The responses of many V2 neurons are also modulated by more complex properties, such as the orientation of [[illusory contours]],<ref name="illusory contours">{{cite journal | vauthors = von der Heydt R, Peterhans E, Baumgartner G | title = Illusory contours and cortical neuron responses | journal = Science | volume = 224 | issue = 4654 | pages = 1260–1262 | date = June 1984 | pmid = 6539501 | doi = 10.1126/science.6539501 | bibcode = 1984Sci...224.1260V }}</ref><ref name="A. Anzai, X. Peng 2007"/> [[binocular disparity]],<ref name="stereoscopic edges">{{cite journal | vauthors = von der Heydt R, Zhou H, Friedman HS | title = Representation of stereoscopic edges in monkey visual cortex | journal = Vision Research | volume = 40 | issue = 15 | pages = 1955–1967 | date = 2000 | pmid = 10828464 | doi = 10.1016/s0042-6989(00)00044-4 | s2cid = 10269181 | doi-access = free }}</ref> and whether the stimulus is part of the figure or the ground.<ref>{{cite journal | vauthors = Qiu FT, von der Heydt R | title = Figure and ground in the visual cortex: v2 combines stereoscopic cues with gestalt rules | journal = Neuron | volume = 47 | issue = 1 | pages = 155–166 | date = July 2005 | pmid = 15996555 | pmc = 1564069 | doi = 10.1016/j.neuron.2005.05.028 }}</ref><ref>{{cite journal | vauthors = Maruko I, Zhang B, Tao X, Tong J, Smith EL, Chino YM | title = Postnatal development of disparity sensitivity in visual area 2 (v2) of macaque monkeys | journal = Journal of Neurophysiology | volume = 100 | issue = 5 | pages = 2486–2495 | date = November 2008 | pmid = 18753321 | pmc = 2585398 | doi = 10.1152/jn.90397.2008 }}</ref> Recent research has shown that V2 cells show a small amount of attentional modulation (more than V1, less than V4), are tuned for moderately complex patterns, and may be driven by multiple orientations at different subregions within a single receptive field.

It is argued that the entire ventral visual-to-hippocampal stream is important for visual memory.<ref>{{cite journal | vauthors = Bussey TJ, Saksida LM | title = Memory, perception, and the ventral visual-perirhinal-hippocampal stream: thinking outside of the boxes | journal = Hippocampus | volume = 17 | issue = 9 | pages = 898–908 | date = 2007 | pmid = 17636546 | doi = 10.1002/hipo.20320 | author-link2 = Lisa Saksida | s2cid = 13271331 }}</ref> This theory, unlike the dominant one, predicts that object-recognition memory (ORM) alterations could result from the manipulation in V2, an area that is highly interconnected within the ventral stream of visual cortices. In the monkey brain, this area receives strong feedforward connections from the primary visual cortex (V1) and sends strong projections to other secondary visual cortices (V3, V4, and V5).<ref>{{cite journal | vauthors = Stepniewska I, Kaas JH | title = Topographic patterns of V2 cortical connections in macaque monkeys | journal = The Journal of Comparative Neurology | volume = 371 | issue = 1 | pages = 129–152 | date = July 1996 | pmid = 8835723 | doi = 10.1002/(SICI)1096-9861(19960715)371:1<129::AID-CNE8>3.0.CO;2-5 | s2cid = 8500842 }}</ref><ref>{{cite journal | vauthors = Gattass R, Sousa AP, Mishkin M, Ungerleider LG | title = Cortical projections of area V2 in the macaque | journal = Cerebral Cortex | volume = 7 | issue = 2 | pages = 110–129 | date = March 1997 | pmid = 9087820 | doi = 10.1093/cercor/7.2.110 | doi-access = free }}</ref> Most of the neurons of this area in primates are tuned to simple visual characteristics such as orientation, spatial frequency, size, color, and shape.<ref name="A. Anzai, X. Peng 2007">{{cite journal | vauthors = Anzai A, Peng X, Van Essen DC | title = Neurons in monkey visual area V2 encode combinations of orientations | journal = Nature Neuroscience | volume = 10 | issue = 10 | pages = 1313–1321 | date = October 2007 | pmid = 17873872 | doi = 10.1038/nn1975 | s2cid = 6796448 }}</ref><ref>{{cite journal | vauthors = Hegdé J, Van Essen DC | title = Selectivity for complex shapes in primate visual area V2 | journal = The Journal of Neuroscience | volume = 20 | issue = 5 | pages = RC61 | date = March 2000 | pmid = 10684908 | pmc = 6772904 | doi = 10.1523/JNEUROSCI.20-05-j0001.2000 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Hegdé J, Van Essen DC | title = Temporal dynamics of shape analysis in macaque visual area V2 | journal = Journal of Neurophysiology | volume = 92 | issue = 5 | pages = 3030–3042 | date = November 2004 | pmid = 15201315 | doi = 10.1152/jn.00822.2003 | s2cid = 6428310 }}</ref> Anatomical studies implicate layer 3 of area V2 in visual-information processing. In contrast to layer 3, layer 6 of the visual cortex is composed of many types of neurons, and their response to visual stimuli is more complex.

In one study, the Layer 6 cells of the V2 cortex were found to play a very important role in the storage of Object Recognition Memory as well as the conversion of short-term object memories into long-term memories.<ref>{{cite journal | vauthors = López-Aranda MF, López-Téllez JF, Navarro-Lobato I, Masmudi-Martín M, Gutiérrez A, Khan ZU | title = Role of layer 6 of V2 visual cortex in object-recognition memory | journal = Science | volume = 325 | issue = 5936 | pages = 87–89 | date = July 2009 | pmid = 19574389 | doi = 10.1126/science.1170869 | s2cid = 23990759 | bibcode = 2009Sci...325...87L }}</ref>