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.
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.
|Papadimitriou, Charalampos; Ferdoash, Afreen; Snyder, Lawrence H (2015) Ghosts in the machine: memory interference from the previous trial. J Neurophysiol 113:567-77|
|Yttri, Eric A; Wang, Cunguo; Liu, Yuqing et al. (2014) The parietal reach region is limb specific and not involved in eye-hand coordination. J Neurophysiol 111:520-32|
|Patel, Gaurav H; Kaplan, David M; Snyder, Lawrence H (2014) Topographic organization in the brain: searching for general principles. Trends Cogn Sci 18:351-63|
|Mooshagian, Eric; Wang, Cunguo; Ferdoash, Afreen et al. (2014) Movement order and saccade direction affect a common measure of eye-hand coordination in bimanual reaching. J Neurophysiol 112:730-9|
|Yttri, Eric A; Liu, Yuqing; Snyder, Lawrence H (2013) Lesions of cortical area LIP affect reach onset only when the reach is accompanied by a saccade, revealing an active eye-hand coordination circuit. Proc Natl Acad Sci U S A 110:2371-6|
|Kubanek, Jan; Snyder, Lawrence H; Brunton, Bingni W et al. (2013) A low-frequency oscillatory neural signal in humans encodes a developing decision variable. Neuroimage 83:795-808|
|Kubanek, J; Wang, C; Snyder, L H (2013) Neuronal responses to target onset in oculomotor and somatomotor parietal circuits differ markedly in a choice task. J Neurophysiol 110:2247-56|
|Chang, Steve W C; Snyder, Lawrence H (2012) The representations of reach endpoints in posterior parietal cortex depend on which hand does the reaching. J Neurophysiol 107:2352-65|
|Liu, Yuqing; Yttri, Eric A; Snyder, Lawrence H (2010) Intention and attention: different functional roles for LIPd and LIPv. Nat Neurosci 13:495-500|
|Patel, Gaurav H; Shulman, Gordon L; Baker, Justin T et al. (2010) Topographic organization of macaque area LIP. Proc Natl Acad Sci U S A 107:4728-33|
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