Recent data suggests the spinal cord of tetrapod vertebrates may be organized into circuits that control forcefield primitives. Recent data from my laboratory shows the temporal dynamics of primitives in spinalized frogs appear to have constant duration in many contexts, including rapid on-line trajectory corrections. We hypothesize this time scale is a conserved characteristic of the spinal circuits. If correct, this time scale defined by a primitive would impact on spinal trajectory formation, motor learning and the partitioning of control between spinal and supraspinal systems. To test the hypothesis in detail we have three specific aims: (1) We will test the hypothesis that all adjustments of trajectory formation in spinal wiping reflex can be understood as regulation of phase and amplitude of primitives but not the duration or temporal dynamics. (2) We will test the hypothesis that individual and ensemble sensory feedback circuits acting on force-field primitives are organized to preserve the temporal dynamics of primitives. (3) We will test how descending controls from medulla and tegmentum recruit and/or reorganize the timing properties of spinal primitives to build adaptable motor behaviors. Our data will bear on trajectory formation at the spinal level, interaction of descending and spinal motor control circuits, neural reorganization, design of neural repair and rehabilitation strategies following injury, design of neuroprostheses, and biomorphic robotics.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
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Integrative, Functional and Cognitive Neuroscience 8 (IFCN)
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Chen, Daofen
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Drexel University
Anatomy/Cell Biology
Schools of Medicine
United States
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Giszter, Simon F (2015) Motor primitives--new data and future questions. Curr Opin Neurobiol 33:156-65
Hart, Corey B; Giszter, Simon F (2013) Distinguishing synchronous and time-varying synergies using point process interval statistics: motor primitives in frog and rat. Front Comput Neurosci 7:52
Giszter, Simon F; Hart, Corey B (2013) Motor primitives and synergies in the spinal cord and after injury--the current state of play. Ann N Y Acad Sci 1279:114-26
Giszter, Simon F; Hockensmith, Greg; Ramakrishnan, Arun et al. (2010) How spinalized rats can walk: biomechanics, cortex, and hindlimb muscle scaling--implications for rehabilitation. Ann N Y Acad Sci 1198:279-93
Hart, Corey B; Giszter, Simon F (2010) A neural basis for motor primitives in the spinal cord. J Neurosci 30:1322-36
Giszter, Simon F; Hart, Corey B; Silfies, Sheri P (2010) Spinal cord modularity: evolution, development, and optimization and the possible relevance to low back pain in man. Exp Brain Res 200:283-306
Kargo, William J; Ramakrishnan, Arun; Hart, Corey B et al. (2010) A simple experimentally based model using proprioceptive regulation of motor primitives captures adjusted trajectory formation in spinal frogs. J Neurophysiol 103:573-90
Giszter, Simon F; Davies, Michelle R; Graziani, Virginia (2008) Coordination strategies for limb forces during weight-bearing locomotion in normal rats, and in rats spinalized as neonates. Exp Brain Res 190:53-69
Kargo, William J; Giszter, Simon F (2008) Individual premotor drive pulses, not time-varying synergies, are the units of adjustment for limb trajectories constructed in spinal cord. J Neurosci 28:2409-25
Giszter, Simon F (2008) Spinal cord injury: present and future therapeutic devices and prostheses. Neurotherapeutics 5:147-62

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