Vision is critical for effective control of action. The dorsal stream projects to the posterior parietal cortex (PPC), and transforms visual input into corresponding responses to guide movements of different effectors. An influential model proposes that the dorsal stream is organized into dedicated visuomotor channels that are effector-specific and operate independently. Experiments for this proposal seek to rigorously test this model against alternatives in which channels guide movements of multiple effectors and can interact. We will first test whether coordinating visually-guided behaviors recruits effector-specific processes by recording neurons in the parietal reach system (Aim 1) and the parietal saccade system (Aim 2) during coordinated behavior. We will then test whether channels operate independently or interact by measuring the strength and functional significance of cross-areal coherence between the parietal reach and saccade systems (Aim 3). Despite the central role of coordination to visual behavior, how visual space for reaching and eye movements influence each other and whether cross-areal interactions within PPC underlie this influence is not known. Understanding the mechanisms of coordinated visual behavior will help us understand how visual behavior arises from interactions between different visual representations more generally. Damage to the PPC leads to optic ataxia, apraxia and neglect, is debilitating, and is suffered by many patients each year in the US with significant social costs. Understanding how the brain constructs visual-spatial representations underlies the effective treatment of patients with posterior parietal damage.
This project aims to understand how spatial representations during coordinated behaviors, such as looking and reaching toward an object, are constructed within neural circuits of the posterior parietal cortex (PPC). Damage to the PPC due to injury or disease, as well as age-related decline, gives rise to many spatial deficits of perception, action and cognition. Understanding how circuits in PPC construct visual representations of space during coordinated behavior will lead to new strategies for neural rehabilitation and support the development of neural prosthetic systems.
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