Human Ventral Occipitotemporal Cortex

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DESCRIPTION (provided by applicant): Damage to regions of the ventral occipitotemporal (VO) cortex can result in subtle perceptual problems, such as achromatopsia and prosopagnosia. Consequently, it is widely believed that the neural circuitry in VO cortex computes mid-level visual properties from the relatively low level input provided by primary visual cortex. However, the relationship among retinotopic organization and color and face responses in human VO cortex has not been carefully measured. For example, it has not been established whether the processing of color and object information occurs within retinotopic cortex or in areas without retinotopic organization, perhaps using a purely translation-invariant computation. The proposed experiments will determine the functional organization of the ventral VO cortex using functional magnetic resonance imaging. The first set of experiments (Aim 1) will map the visual field responses of VO cortex. These retinotopic maps will be compared with the color-selective and face/object selective regions determined in Aim 2 and Aim 3. These experiments should resolve the question of retinotopic organization in regions that respond selectively to color and faces/objects. These experiments will also clarify the spatial relationship among foveal, color, and object responses in VO cortex. Understanding the normal functional organization of this cortical region will serve two purposes. First, it will enhance our knowledge of how the brain processes mid-level visual information about object properties. Second, it may help us understand the variability in the severity and in the degree of recovery of visual deficits from VO cortical lesions.