Editing Visual cortex (section)

=== Function ===
The first studies of the [[electrophysiological]] properties of neurons in MT showed that a large portion of the cells are [[neuronal tuning|tuned]] to the speed and direction of moving visual stimuli.<ref name="DubnerZeki">{{cite journal | vauthors = Dubner R, Zeki SM | title = Response properties and receptive fields of cells in an anatomically defined region of the superior temporal sulcus in the monkey | journal = Brain Research | volume = 35 | issue = 2 | pages = 528–532 | date = December 1971 | pmid = 5002708 | doi = 10.1016/0006-8993(71)90494-X }}.</ref><ref name="MaunsellVanEssen">{{cite journal | vauthors = Maunsell JH, Van Essen DC | title = Functional properties of neurons in middle temporal visual area of the macaque monkey. I. Selectivity for stimulus direction, speed, and orientation | journal = Journal of Neurophysiology | volume = 49 | issue = 5 | pages = 1127–1147 | date = May 1983 | pmid = 6864242 | doi = 10.1152/jn.1983.49.5.1127 | s2cid = 8708245 }}</ref>

[[Lesion]] studies have also supported the role of MT in motion perception and eye movements.<ref name=Dursteler1987>{{cite journal | vauthors = Dürsteler MR, Wurtz RH, Newsome WT | title = Directional pursuit deficits following lesions of the foveal representation within the superior temporal sulcus of the macaque monkey | journal = Journal of Neurophysiology | volume = 57 | issue = 5 | pages = 1262–1287 | date = May 1987 | pmid = 3585468 | doi = 10.1152/jn.1987.57.5.1262 | citeseerx = 10.1.1.375.8659 }}</ref> [[Neuropsychology|Neuropsychological]] studies of a patient unable to see motion, seeing the world in a series of static 'frames' instead, suggested that V5 in the primate is homologous to MT in the human.<ref name=Hess1989>{{cite journal | vauthors = Hess RH, Baker CL, Zihl J | title = The "motion-blind" patient: low-level spatial and temporal filters | journal = The Journal of Neuroscience | volume = 9 | issue = 5 | pages = 1628–1640 | date = May 1989 | pmid = 2723744 | pmc = 6569833 | doi = 10.1523/JNEUROSCI.09-05-01628.1989 }}</ref><ref name=Baker1991>{{cite journal | vauthors = Baker CL, Hess RF, Zihl J | title = Residual motion perception in a "motion-blind" patient, assessed with limited-lifetime random dot stimuli | journal = The Journal of Neuroscience | volume = 11 | issue = 2 | pages = 454–461 | date = February 1991 | pmid = 1992012 | pmc = 6575225 | doi = 10.1523/JNEUROSCI.11-02-00454.1991 }}</ref>

However, since neurons in V1 are also tuned to the direction and speed of motion, these early results left open the question of precisely what MT could do that V1 could not. Much work has been carried out on this region, as it appears to integrate local visual motion signals into the global motion of complex objects.<ref name="Movshon">Movshon, J.A., Adelson, E.H., Gizzi, M.S., & Newsome, W.T. (1985). The analysis of moving visual patterns. In: C. Chagas, R. Gattass, & C. Gross (Eds.), Pattern recognition mechanisms (pp. 117–151), Rome: Vatican Press.</ref>
For example, ''lesion'' to the V5 leads to deficits in perceiving motion and processing of complex stimuli. It contains many neurons selective for the motion of complex visual features (line ends, corners). ''Microstimulation'' of a neuron located in the V5 affects the perception of motion. For example, if one finds a neuron with preference for upward motion in a monkey's V5 and stimulates it with an electrode, then the monkey becomes more likely to report 'upward' motion when presented with stimuli containing 'left' and 'right' as well as 'upward' components.<ref name="BrittenVanWezel">{{cite journal | vauthors = Britten KH, van Wezel RJ | title = Electrical microstimulation of cortical area MST biases heading perception in monkeys | journal = Nature Neuroscience | volume = 1 | issue = 1 | pages = 59–63 | date = May 1998 | pmid = 10195110 | doi = 10.1038/259 | s2cid = 52820462 }}</ref>

There is still much controversy over the exact form of the computations carried out in area MT<ref name="Wilson">{{cite journal | vauthors = Wilson HR, Ferrera VP, Yo C | title = A psychophysically motivated model for two-dimensional motion perception | journal = Visual Neuroscience | volume = 9 | issue = 1 | pages = 79–97 | date = July 1992 | pmid = 1633129 | doi = 10.1017/s0952523800006386 | s2cid = 45196189 }}</ref> and some research suggests that feature motion is in fact already available at lower levels of the visual system such as V1.<ref name="Tinsley">{{cite journal | vauthors = Tinsley CJ, Webb BS, Barraclough NE, Vincent CJ, Parker A, Derrington AM | title = The nature of V1 neural responses to 2D moving patterns depends on receptive-field structure in the marmoset monkey | journal = Journal of Neurophysiology | volume = 90 | issue = 2 | pages = 930–937 | date = August 2003 | pmid = 12711710 | doi = 10.1152/jn.00708.2002 | s2cid = 540146 }}</ref><ref name="PackBorn">{{cite journal | vauthors = Pack CC, Born RT, Livingstone MS | title = Two-dimensional substructure of stereo and motion interactions in macaque visual cortex | journal = Neuron | volume = 37 | issue = 3 | pages = 525–535 | date = February 2003 | pmid = 12575958 | doi = 10.1016/s0896-6273(02)01187-x | doi-access = free }}</ref>