Primates, including humans, are expert at coordinating their arms and eyes in skillful behavior. Our goal is to understand the neural circuitry that underlies the combination of bimanual coordination and eye-hand coordination, which we call ?hand-eye-hand? (HEH) coordination. We are particularly interested in the early planning of bimanual movements, and the role-effector specific areas in the posterior parietal cortex play in that planning. We hypothesize that inter-areal and inter-hemispheric communication is necessary for HEH coordination. For example, the parietal reach region (PRR) controls primarily the contralateral arm. One way for one hand to know what the other is doing, so to speak, is for information to be exchanged between PRR in each hemisphere. The most direct pathway for such communication is through the corpus callosum, a major fiber tract connecting the two hemispheres. The relative accessibility of the corpus callosum provides an opportunity for causal tests of the role callosum plays in particular, and of inter-hemispheric communication in general, in HEH coordination. Lidocaine injections can reversibly block conduction through particular portions of the callosum, and behavior and neuronal activity can be compared in behaving animals before, during and after blockade. We predict that HEH coordination will be impaired when particular ?ber tracts within the callosum are blocked, and that there will be neuronal correlates of that impairment within the brain areas responsible for the behavior. Our ?rst Aim is to establish where in the callosum particular axonal tracts cross, and to verify that we can reversibly block conduction through those pathways. Next, for our second Aim, we will test speci?c hypotheses regarding which behaviors will be affected when particular pathways are blocked. We will consider pathways to and from the parietal reach region (PRR) and the lateral intraparietal area (LIP), an analogous area that codes saccade plans. Animals will perform interleaved, natural unimanual and bimanual reaches and saccades. We will then, in our third Aim, examine activity within PRR and LIP to determine how speci?c neuronal circuits are impacted by the transient loss of speci?c callosal pathways. Bimanual HEH coordination is critical for normal human behavior, yet the neuronal circuits involved remain largely unknown. This work will greatly expand our understanding of how parietal cortex achieves complex yet ?exible coordination of body parts. The information will be relevant to coordination in other effector systems, and will help us design the next generation of brain-computer interfacing prosthetics that can leverage natural coordination patterns and coordinate with existing limbs and eye movements. Further, we will learn fundamental facts about the role of the corpus callosum in the brain. Finally, this work will shed light on the general issue of long range communication across brain areas, and how this communication is related to brain function.
The central goal of this proposal is to understand the neural systems subserving coordinated eye and arm movements, and in particular, the role of the corpus callosum, a structure connecting the two halves of the brain. Coordinated movements are central to our daily functions, yet are often compromised by strokes, trauma and degenerative diseases. A better understanding of the brain systems underlying coordination may benefit clinical diagnosis and prognosis in these conditions and eventually lead to improved treatment, including, for example, limb prostheses that support natural coordination with an existing limb or between a pair of prosthetic limbs.
| 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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