Visual modularity: Difference between revisions

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Revision as of 16:58, 26 December 2014

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==Motion processing==

[[Akinetopsia]] is an intriguing condition brought about by damage to the [[Extrastriate cortex]] MT+ that renders [[humans]] and [[monkeys]] unable to perceive motion, seeing the world in a series of static "frames" instead<ref name="zihl1">{{cite journal|last=Zihl|first=J.|coauthors=von Cramon, D.Y., Mai N., Schmid, C.|year=1991|title=Disturbance of movement vision after bilateral posterior brain damage|journal=Brain|issue=144|doi=10.1093/brain/114.5.2235|pages=2235–2252|volume=114|pmid=1933243}}</ref><ref name="zihl2">{{cite journal|last=Zihl|first=J.|coauthors=von Cramon, D.Y., Mai, N.|year=1983|title=Selective disturbances of movement vision after bilateral brain damage|journal=Brain|issue=106|doi=10.1093/brain/106.2.525-a|pages=313–340|volume=106}}</ref><ref name=Hess1989>{{cite journal | title=The" motion-blind" patient: low-level spatial and temporal filters | author=Hess, Baker, Zihl | journal=Journal of Neuroscience | year=1989 | volume=9 | issue=5 | pages=1628–1640 | pmid=2723744}}</ref><ref name=Baker1991>{{cite journal | title=Residual motion perception in a" motion-blind" patient, assessed with limited-lifetime random dot stimuli | author=Baker, Hess, Zihl | journal=Journal of Neuroscience | year=1991 | volume=11 | issue=2 | pages=454–461 | pmid=1992012}}</ref> and indicates that there might be a "motion centre" in the brain. Of course, such data can only indicate that this area is at least necessary to motion perception, not that it is sufficient; however, other evidence has shown the importance of this area to primate motion perception. Specifically, physiological, neuroimaging, perceptual, electrical- and [[transcranial magnetic stimulation]] evidence (Table 1) all come together on the area V5/hMT+. Converging evidence of this type is supportive of a module for motion processing. However, this view is likely to be incomplete: other areas are involved with [[motion perception]], including V1,<ref name="orban1">{{cite journal|last=Orban|first=G.A.|author2=Kennedy, H. |author3=Bullier, J. |year=1986|title=Velocity sensitivity and direction selectivity of neurons in areas V1 and V2 of the monkey: influence of eccentricity|journal=Journal of Neurophysiology|volume=56|issue=2|doi=10.1016/j.jphysparis.2004.03.004|pages=462–480|pmid=3760931}}</ref><ref name="mov1">{{cite journal|last=Movshon|first=J.A.|author2=Newsome, W.T. |year=1996|title=Visual response properties of striate cortical neurons projecting to area MT in macaque monkeys|journal=Journal of Neuroscience|volume=16|issue=23|pages=7733–7741|pmid=8922429}}</ref><ref>{{cite journal|last=Born|first=R.T.|author2=Bradley, D.C. |year=2005|title=Structure and function of visual area MT|journal=Annual Review of Neuroscience|volume=28|pages=157–189|pmid=16022593|doi=10.1146/annurev.neuro.26.041002.131052}}</ref> V2 and V3a <ref>{{cite journal|last=Grill-Spector|first=K.|author2=Malach, R. |year=2004|title=The Human Visual Cortex|journal=Annual Review of Neuroscience|volume=7|pages=649–677|doi=10.1146/annurev.neuro.27.070203.144220|pmid=15217346}}</ref> and areas surrounding V5/hMT+ (Table 2). A recent fMRI study put the number of motion areas at twenty-one.<ref name="stiers">{{cite journal|last=Stiers|first=P|coauthors=Peeters, R; Lagae, L; Van Hecke, P; Sunaert, S|title=Mapping multiple visual areas in the human brain with a short fMRI sequence|journal=NeuroImage|date=Jan 1, 2006|year=2006|volume=29|issue=1|pages=74–89|doi=10.1016/j.neuroimage.2005.07.033|pmid=16154766|url=http://www.sciencedirect.com/science/article/pii/S1053811905005070|accessdate=28 April 2013}}</ref> Clearly, this constitutes a stream of diverse anatomical areas. The extent to which this is ‘pure’ is in question: with Akinetopsia come severe difficulties in obtaining structure from motion.<ref name=rizzo>{{cite journal|last=Rizzo|first=Matthew|author2=Nawrot, Mark |author3=Zihl, Josef |title=Motion and shape perception in cerebral akinetopsia|journal=Brain|date=1 January 1995|volume=118|issue=5|pages=1105–1127|doi=10.1093/brain/118.5.1105|pmid=7496774}}</ref> [[V5/hMT+]] has since been implicated in this function<ref name=grunewald>{{cite journal|last=Grunewald|first=A|author2=Bradley, DC |author3=Andersen, RA |title=Neural correlates of structure-from-motion perception in macaque V1 and MT|journal=The Journal of neuroscience : the official journal of the Society for Neuroscience|date=Jul 15, 2002|volume=22|issue=14|pages=6195–207|pmid=12122078}}</ref> as well as determining depth.<ref name=angelis>{{cite journal|last=DeAngelis|first=GC|author2=Cumming, BG |author3=Newsome, WT |title=Cortical area MT and the perception of stereoscopic depth|journal=Nature|date=Aug 13, 1998|volume=394|issue=6694|pages=677–80|doi=10.1038/29299|pmid=9716130}}</ref> Thus the current evidence suggests that motion processing occurs in a modular stream, although with a role in form and depth perception at higher levels.

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