Shape representation in ventral pathway visual cortex

Shape processing is a critical perceptual faculty that underlies almost all our interactions with the world. Our extraordinary ability to discriminate and recognize shapes depends on as yet unknown neural mechanisms in the ventral pathway of primate visual cortex. We explored shape-processing mechanisms in area V4, an intermediate ventral pathway stage in humans and lower primates. Our experiments involved recording electrical activity from individual neurons in awake macaque monkeys performing a fixation task while parametrically varying shape stimuli were flashed in the receptive field of the neuron under study. Our results showed that V4 neurons represent information about contour shape in localized object regions. At the population level, V4 represents complete objects in terms of their constituent parts by means of multiple activity peaks in the shape×position domain.