VISUAL-MOTOR TRANSFORMATIONS IN PARIETAL CORTEX

Washington University, Saint Louis MO

Investigators

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Abstract

DESCRIPTION (Adapted From The Applicant's Abstract): This proposal will investigate the role of the posterior parietal cortex in directing movements to visible targets. The parietal cortex clearly plays a role in this process, but the nature of that role is unresolved. Complicating the issue is the fact that parietal cortex contains multiple fields, many of which are involved in the processing of visual spatial information, and some of which appear to be related to the movements of particular body parts. A common approach to studying the role of these fields in transforming sensory information into motor commands has been to consider the frame of reference of the spatial information that each contains. The PI now proposes to study, in addition, whether and how the information is specifically related to arm, eye and head movements (motor specificity). The development of motor specific responses relates to the selection of a particular motor response, a critical stage in the sensory to motor transformation. It is suggested that response selection and reference frame transformation are two distinct and potentially separable components of that transformation. This approach is a significant departure from previous work, which has typically considered only a single motor output. Aim I will characterize the exact relationship between motor specificity and frame of reference for activity in the ventral intraparietal area (VIP). The experiments and their analysis are designed to capture the full range and potential richness of the properties of individual neurons, rather than merely categorizing them as "motor" or "sensory." Aim 2 will examine motor-specific activity in the lateral intraparietal area (LIP) and in the parietal reach region (PRR). We will determine how signals encoding the decision to take one course of action or another interact with signals encoding spatial information. Finally, Aim 3 will challenge an established hypothesis concerning spatial information processing in LIP. The hypothesis has important ramifications for whether processing may be directed towards specific motor outputs. Taken together, the results of these aims are likely to provide new insight into the role of parietal cortex in the sensory to motor transformation in general, and in particular, into the role of specific fields in directing eye, arm and head movements to visual targets.