Our long-term goal is to understand visuospatial processing in the brain and the neural mechanisms underlying visually-guided movements. Most actions involve coordination across multiple body parts, and so understanding coordination is instrumental to understanding visuomotor processing in general. We will look specifically at the coordination of the two hands (bimanual coordination) and the eye and hand (eye-hand coordination) in the macaque monkey. In this grant cycle, we focus on the parietal reach region (PRR) in the posterior parietal cortex, a key nexus of sensory, motor and attentional processing. In future cycles, we will extend these studies to other brain areas.
Our first aim elucidates the role PRR plays (if any) in bimanual coordination. We focus on ipsilateral limb information in PRR and on interhemispheric communication. We will record from neurons during different types of bimanual coordination tasks, all of which require synchronous behavior of the two hands. We will quantify the synchrony of behavior and then determine whether and how PRR activity (single units and LFP) reflects the type of bimanual coordination task and the level of synchrony that is actually achieved. We will also assess information transfer across the two hemispheres and ask if this varies by task and degree of coordination.
Our second aim i s similar, but adds in the additional dimension of eye movements, spontaneously deployed by animals as they perform these tasks. We will evaluate whether and how PRR reflects different patterns of eye-hand coordination.
Our final aim addresses the coding of static eye and hand positions in a bimanual task. In the previous grant cycle, we described an encoding of the distance between gaze and hand in PRR during a unimanual task. Based upon the format of that encoding, we argued that PRR plays a role in reference frame transformations. Discovering whether and how this encoding is maintained in a bimanual task - when there are two eye-hand distances rather than only one to encode - will provide critical information about what computations can or cannot be performed in PRR, and will provide further evidence for, or against, the hypothesis that PRR is involved in bimanual and/or eye-hand coordination. The paradigms we are developing should allow us to identify signals in PRR and elsewhere that are related to motor coordination. Achieving our aim will advance our understanding of the role of PRR in bimanual and eye-hand coordination and also provide invaluable information about how cross-effector and cross-system coordination is achieved in the brain.

Public Health Relevance

The central goal of this proposal is to understand the neural systems subserving coordinated motor behavior. Strokes and degenerative diseases often affect our ability to coordinate movements. A better understanding of the brain systems underlying coordination will thus improve diagnosis and enhance our ability to predict clinical outcomes after trauma and disease, and may eventually lead to improved treatment. Because we will learn general principles of coordination in the central nervous system, this information may also find application in diagnosing and treating cognitive dysfunction that follows from disrupted communication after strokes and other insults. Finally, our work will provide critical information for designing and building tomorrow's prostheses, useful for patients with amputations, spinal cord injuries, and disorders such as amyotrophic lateral sclerosis.

National Institute of Health (NIH)
National Eye Institute (NEI)
Research Project (R01)
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Araj, Houmam H
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Washington University
Schools of Medicine
Saint Louis
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Holmes, Charles D; Papadimitriou, Charalampos; Snyder, Lawrence H (2018) Dissociation of LFP Power and Tuning in the Frontal Cortex during Memory. J Neurosci 38:8177-8186
Mooshagian, Eric; Snyder, Lawrence H (2018) Spatial eye-hand coordination during bimanual reaching is not systematically coded in either LIP or PRR. Proc Natl Acad Sci U S A 115:E3817-E3826
Mooshagian, Eric; Wang, Cunguo; Holmes, Charles D et al. (2018) Single Units in the Posterior Parietal Cortex Encode Patterns of Bimanual Coordination. Cereb Cortex 28:1549-1567
Kubanek, Jan; Snyder, Lawrence H (2017) Reward Size Informs Repeat-Switch Decisions and Strongly Modulates the Activity of Neurons in Parietal Cortex. Cereb Cortex 27:447-459
Papadimitriou, Charalampos; White 3rd, Robert L; Snyder, Lawrence H (2017) Ghosts in the Machine II: Neural Correlates of Memory Interference from the Previous Trial. Cereb Cortex 27:2513-2527
Chang, Steve W C; Calton, Jeffrey L; Lawrence, Bonnie M et al. (2016) Region-Specific Summation Patterns Inform the Role of Cortical Areas in Selecting Motor Plans. Cereb Cortex 26:2154-66
Kubanek, Jan; Snyder, Lawrence H; Abrams, Richard A (2015) Reward and punishment act as distinct factors in guiding behavior. Cognition 139:154-67
Kubanek, Jan; Snyder, Lawrence H (2015) Matching Behavior as a Tradeoff Between Reward Maximization and Demands on Neural Computation. F1000Res 4:147
Patel, Gaurav H; Yang, Danica; Jamerson, Emery C et al. (2015) Functional evolution of new and expanded attention networks in humans. Proc Natl Acad Sci U S A 112:9454-9
Papadimitriou, Charalampos; Ferdoash, Afreen; Snyder, Lawrence H (2015) Ghosts in the machine: memory interference from the previous trial. J Neurophysiol 113:567-77

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