Editing Visual cortex (section)

==V6==
<!-- [[Dorsomedial area]] redirects to this section -->
The '''dorsomedial area''' (DM) also known as '''V6''', appears to respond to visual stimuli associated with self-motion<ref>{{cite journal | vauthors = Cardin V, Smith AT | title = Sensitivity of human visual and vestibular cortical regions to egomotion-compatible visual stimulation | journal = Cerebral Cortex | volume = 20 | issue = 8 | pages = 1964–1973 | date = August 2010 | pmid = 20034998 | pmc = 2901022 | doi = 10.1093/cercor/bhp268 }}</ref> and wide-field stimulation.<ref name= humanV6 >{{cite journal | vauthors = Pitzalis S, Galletti C, Huang RS, Patria F, Committeri G, Galati G, Fattori P, Sereno MI | title = Wide-field retinotopy defines human cortical visual area v6 | journal = The Journal of Neuroscience | volume = 26 | issue = 30 | pages = 7962–7973 | date = July 2006 | pmid = 16870741 | pmc = 6674231 | doi = 10.1523/jneurosci.0178-06.2006 }}</ref> V6 is a subdivision of the visual cortex of primates first described by [[John Allman]] and [[Jon Kaas]] in 1975.<ref>{{cite journal | vauthors = Allman JM, Kaas JH | title = The dorsomedial cortical visual area: a third tier area in the occipital lobe of the owl monkey (Aotus trivirgatus) | journal = Brain Research | volume = 100 | issue = 3 | pages = 473–487 | date = December 1975 | pmid = 811327 | doi = 10.1016/0006-8993(75)90153-5 | s2cid = 22980932 }}</ref> V6 is located in the dorsal part of the [[extrastriate cortex]], near the deep groove through the centre of the brain ([[medial longitudinal fissure]]), and typically also includes portions of the medial cortex, such as the [[parieto-occipital sulcus]] (POS).<ref name= humanV6 />{{rp|7970}} DM contains a topographically organized representation of the entire field of vision.<ref name= humanV6 />{{rp|7970}}

There are similarities between the visual area V5 and V6 of the [[common marmoset]]. Both areas receive direct connections from the [[primary visual cortex]].<ref name= humanV6 />{{rp|7971}} And both have a high [[myelin]] content, a characteristic that is usually present in brain structures involved in fast transmission of information.<ref name="pitzalis2012">{{cite journal | vauthors = Pitzalis S, Fattori P, Galletti C | title = The functional role of the medial motion area V6 | journal = Frontiers in Behavioral Neuroscience | volume = 6 | pages = 91 | year = 2013 | pmid = 23335889 | pmc = 3546310 | doi = 10.3389/fnbeh.2012.00091 | doi-access = free }}</ref>

For many years, it was considered that DM only existed in [[New World monkeys]]. However, more recent research has suggested that DM also exists in [[Old World monkeys]] and humans.<ref name= humanV6 />{{rp|7972}} V6 is also sometimes referred to as the parieto-occipital area (PO), although the correspondence is not exact.<ref>{{cite journal | vauthors = Galletti C, Gamberini M, Kutz DF, Baldinotti I, Fattori P | title = The relationship between V6 and PO in macaque extrastriate cortex | journal = The European Journal of Neuroscience | volume = 21 | issue = 4 | pages = 959–970 | date = February 2005 | pmid = 15787702 | doi = 10.1111/j.1460-9568.2005.03911.x | url = http://www.gallettilab.unibo.it/Pdf/Galletti%20et%20al%202005.pdf | access-date = 2018-09-14 | s2cid = 15020868 | citeseerx = 10.1.1.508.5602 | archive-url = https://web.archive.org/web/20170808041058/http://www.gallettilab.unibo.it/Pdf/Galletti%20et%20al%202005.pdf | archive-date = 2017-08-08 }}</ref><ref name="Gal">{{cite journal | vauthors = Galletti C, Kutz DF, Gamberini M, Breveglieri R, Fattori P | title = Role of the medial parieto-occipital cortex in the control of reaching and grasping movements | journal = Experimental Brain Research | volume = 153 | issue = 2 | pages = 158–170 | date = November 2003 | pmid = 14517595 | doi = 10.1007/s00221-003-1589-z | s2cid = 1821863 }}</ref>

===Properties===
Neurons in area DM/V6 of [[night monkey]]s and [[common marmoset]]s have unique response properties, including an extremely sharp selectivity for the orientation of visual contours, and preference for long, uninterrupted lines covering large parts of the visual field.<ref>{{cite journal | vauthors = Baker JF, Petersen SE, Newsome WT, Allman JM | title = Visual response properties of neurons in four extrastriate visual areas of the owl monkey (Aotus trivirgatus): a quantitative comparison of medial, dorsomedial, dorsolateral, and middle temporal areas | journal = Journal of Neurophysiology | volume = 45 | issue = 3 | pages = 397–416 | date = March 1981 | pmid = 7218008 | doi = 10.1152/jn.1981.45.3.397 | s2cid = 9865958 }}</ref><ref>{{cite journal | vauthors = Lui LL, Bourne JA, Rosa MG | title = Functional response properties of neurons in the dorsomedial visual area of New World monkeys (Callithrix jacchus) | journal = Cerebral Cortex | volume = 16 | issue = 2 | pages = 162–177 | date = February 2006 | pmid = 15858163 | doi = 10.1093/cercor/bhi094 | doi-access = free }}</ref>

However, in comparison with area MT, a much smaller proportion of DM cells shows selectivity for the direction of motion of visual patterns.<ref name="fmritools.com">{{Cite web | vauthors = Ducreux D |title=Calcarine (Visual) Cortex |website=Connectopedia Knowledge Database |url=http://www.fmritools.com/kdb/grey-matter/occipital-lobe/calcarine-visual-cortex/index.html |access-date=2018-01-25|url-status=unfit |archive-date=2018-01-20|archive-url=https://web.archive.org/web/20180120053123/http://www.fmritools.com/kdb/grey-matter/occipital-lobe/calcarine-visual-cortex/index.html}}</ref> Another notable difference with area MT is that cells in DM are attuned to low spatial frequency components of an image, and respond poorly to the motion of textured patterns such as a field of random dots.<ref name="fmritools.com"/> These response properties suggest that DM and MT may work in parallel, with the former analyzing self-motion relative to the environment, and the latter analyzing the motion of individual objects relative to the background.<ref name="fmritools.com"/>

Recently, an area responsive to wide-angle flow fields has been identified in the human and is thought to be a homologue of macaque area V6.<ref>{{cite journal | vauthors = Pitzalis S, Sereno MI, Committeri G, Fattori P, Galati G, Patria F, Galletti C | title = Human v6: the medial motion area | journal = Cerebral Cortex | volume = 20 | issue = 2 | pages = 411–424 | date = February 2010 | pmid = 19502476 | pmc = 2803738 | doi = 10.1093/cercor/bhp112 }}</ref>

===Pathways===
[[File:Neural pathway diagram.svg|thumb]]
The connections and response properties of cells in DM/V6 suggest that this area is a key node in a subset of the "[[dorsal stream]]", referred to by some as the "dorsomedial pathway".<ref name="dorsoMedialP">{{cite journal | vauthors = Fattori P, Raos V, Breveglieri R, Bosco A, Marzocchi N, Galletti C | title = The dorsomedial pathway is not just for reaching: grasping neurons in the medial parieto-occipital cortex of the macaque monkey | journal = The Journal of Neuroscience | volume = 30 | issue = 1 | pages = 342–349 | date = January 2010 | pmid = 20053915 | pmc = 6632536 | doi = 10.1523/JNEUROSCI.3800-09.2010 | doi-access = free }}</ref> This pathway is likely to be important for the control of skeletomotor activity, including postural reactions and reaching movements towards objects<ref name="Gal"/> The main 'feedforward' connection of DM is to the cortex immediately rostral to it, in the interface between the occipital and parietal lobes (V6A).<ref name="dorsoMedialP"/> This region has, in turn, relatively direct connections with the regions of the frontal lobe that control arm movements, including the [[premotor cortex]].<ref name="dorsoMedialP"/><ref>{{cite journal | vauthors = Monaco S, Malfatti G, Zendron A, Pellencin E, Turella L | title = Predictive coding of action intentions in dorsal and ventral visual stream is based on visual anticipations, memory-based information and motor preparation | journal = Brain Structure & Function | volume = 224 | issue = 9 | pages = 3291–3308 | date = December 2019 | pmid = 31673774 | doi = 10.1007/s00429-019-01970-1 | s2cid = 207811473 }}</ref>