Larry Snyder, MD,PhD

Dr. Snyder’s laboratory studies focus on how locations in space are represented in the cerebral cortex, and how those representations are used to guide eye and arm movements. More generally, how is sensory spatial information transformed into commands for movement? And, given a system in which this occurs, how can we analyze that transformation? Parietal cortex has long been implicated in the transformation of visual sensory information into motor commands.

A patient with unilateral parietal damage may ignore objects in one half of the world, clothe only half of their body or eat from only half of their plate. Spatial memory is affected, and there are often motor deficits as well.

In order to understand the role of the parietal cortex in representing space and subserving movement, we record from individual neurons in macaque monkeys while they perform complex visuo-motor tasks. The animals are trained to look at and reach for colored spots of light – a monkey video game. We ask how the locations of these spots are represented by neural activity in the brain. What frame of reference is used? Is there a single, generic representation or multiple special purpose representations? How is spatial information from other sensory systems combined with visually-derived information? How does the nature of the task, and what the animal intends to do, affect parietal processing? Is parietal cortex specifically involved in the learning of new sensory-motor mappings, or in coordinating eye and hand movement?