Visual maps found in higher-order cortex
Faculty member Sabine Kastner and members of her Neuroscience of Attention & Perception Laboratory (Michael Arcaro, Mark Pinsk, and Xin Li) have shown that the posterior parietal cortex in the macaque monkey contains several topographic “maps” of visual space. Using macaques trained to lie inside an MRI scanner and view images presented on a computer screen, these scientists have identified three distinct representations of visual space in parietal cortex—well beyond the known maps of early visual cortex. Two of these maps are within caudal intraparietal cortex and one is within the lateral intraparietal sulcus (LIP). This LIP area has been the subject of much research on the control of eye movements and the allocation of attention to salient locations in the environment, but the presence of an orderly visual map has, until now, been controversial and elusive.
These new results demonstrate that visual topography is not just a fundamental organizing principle of primary visual areas, but also a significant organizing principle for higher-order visual cortex. Furthermore, they suggest fundamental differences in the organization and function of areas in posterior parietal cortex between humans and monkeys, and highlight the unique benefit of performing fMRI in both species to explore these differences directly.
Their results are published February 9, 2011 in the Journal of Neuroscience.
Comparison of fMRI-defined visuotopic organization of dorsal occipital and parietal cortex in both monkeys (left column) and humans (right column).
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