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Jie Lu, Anna Roe, Haidong Lu; Response to motion contrast in macaque V2. Journal of Vision 2010;10(7):944. doi: https://doi.org/10.1167/10.7.944.
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© ARVO (1962-2015); The Authors (2016-present)
Motion processing in monkey visual cortex occurs in the dorsal pathway V1 to MT. However, direction-selective neurons are also found in many ventral areas including V2 and V4. Previously we have reported that direction-selective neurons are clustered in V2 and form patches of direction maps. These maps were observed mainly in V2 thick stripes and never co-localized with color-activated thin stripes. The functional significance of these direction-selective neurons and their maps remains unclear. One possibility is that these neurons contribute to motion defined features and their clustering may facilitate interactions among different direction-selective neurons. Using intrinsic optical imaging methods, we imaged V2 response to motion contrast stimuli in both anesthetized and awake macaque monkeys. These stimuli contain drifting random dots (RD) moving on different backgrounds including 1. homogeneous gray, 2. stationary RD, 3. oppositely-moving RD. We found that V2 direction domains were more strongly activated by the third stimulus (which contains the strongest motion contrast) than to the other two conditions. Random dots moving on stationary RD background elicited weaker response but still stronger than that to pure drifting RD patterns. Combined with the presence of motion contour response in V2, these observations support the idea that V2 plays important roles in analyzing figure-ground segregation based on motion contrast.
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