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Taekjun Kim, Wyeth Bair, Anitha Pasupathy; Neural responses to shape and texture stimuli in macaque area V4. Journal of Vision 2017;17(10):291. doi: 10.1167/17.10.291.
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© ARVO (1962-2015); The Authors (2016-present)
Functional and anatomical evidence demonstrates that visual information is processed along the dorsal and ventral visual pathways in the primate. Area V4 is an important intermediate stage of the ventral visual pathway, which is specialized for object recognition. Several studies agree that V4 neurons respond to visual shape properties (e.g., contour features along a shape boundary), and surface properties (e.g., color, brightness, and texture). However, the main role of V4 in vision has been extensively debated. In the current study, we examined which of object boundary and surface characteristics has a greater impact on V4 single unit activity by presenting simple 2D shape stimuli and texture patches to the same neurons. Our findings showed that simple 2D shape stimuli typically evoked stronger responses from V4 single units compared to texture patches contained within the receptive field or extending beyond. In many cells (>40% of our cell population), neural responses to circular texture patches were tuned to crucial dimensions of texture perception – coarseness, directionality, and regularity. However, response variation attributable to texture information was largely influenced by the cells' preference for a visual shape defined by texture stimuli. Texture stimuli that defined the surface of preferred but not non-preferred visual shape could yield response variation. Preferred visual shape of a single unit was unchanged under various texture conditions within the shapes. Unlike standard shape stimuli which affect both transient and sustained activity of V4 neurons, neural response variation due to the texture information was reflected mostly in sustained activity as a form of suppression. These results suggest that the main role of V4 neurons in object recognition is to represent shape information which is largely consistent across surface properties.
Meeting abstract presented at VSS 2017
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