Edgerton, V. Reggie and Courtine, Grégoire and Gerasimenko, Yury P. and Lavrov, Igor and Ichiyama, Ronaldo M. and Fong, Andy J. and Cai, Lance L. and Otoshi, Chad K. and Tillakaratne, Niranjala J. K. and Burdick, Joel W. and Roy, Roland R. (2008) Training locomotor networks. Brain Research Reviews, 57 (1). pp. 241-254. ISSN 0165-0173 http://resolver.caltech.edu/CaltechAUTHORS:20100505-150446478
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For a complete adult spinal rat to regain some weight-bearing stepping capability, it appears that a sequence of specific proprioceptive inputs that are similar, but not identical, from step to step must be generated over repetitive step cycles. Furthermore, these cycles must include the activation of specific neural circuits that are intrinsic to the lumbosacral spinal cord segments. For these sensorimotor pathways to be effective in generating stepping, the spinal circuitry must be modulated to an appropriate excitability level. This level of modulation is sustained from supraspinal input in intact, but not spinal, rats. In a series of experiments with complete spinal rats, we have shown that an appropriate level of excitability of the spinal circuitry can be achieved using widely different means. For example, this modulation level can be acquired pharmacologically, via epidural electrical stimulation over specific lumbosacral spinal cord segments, and/or by use-dependent mechanisms such as step or stand training. Evidence as to how each of these treatments can “tune” the spinal circuitry to a “physiological state” that enables it to respond appropriately to proprioceptive input will be presented. We have found that each of these interventions can enable the proprioceptive input to actually control extensive details that define the dynamics of stepping over a range of speeds, loads, and directions. A series of experiments will be described that illustrate sensory control of stepping and standing after a spinal cord injury and the necessity for the “physiological state” of the spinal circuitry to be modulated within a critical window of excitability for this control to be manifested. The present findings have important consequences not only for our understanding of how the motor pattern for stepping is formed, but also for the design of rehabilitation intervention to restore lumbosacral circuit function in humans following a spinal cord injury.
|Additional Information:||© 2007 Elsevier B.V. Accepted 11 September 2007. Available online 16 September 2007. The work presented in this paper was supported by NIH NS16333, NIH NS42291, RFBR-CRDF 07-04-91106, the Christopher and Diana Reeve Foundation, and the California Roman Reed Bill.|
|Subject Keywords:||Spinal cord injury; Use-dependent plasticity; Epidural stimulation; Afferent control|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||05 May 2010 22:32|
|Last Modified:||26 Dec 2012 12:00|
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