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Epidural Stimulation Induced Modulation of Spinal Locomotor Networks in Adult Spinal Rats

Lavrov, Igor and Dy, Christine J. and Fong, Andy J. and Gerasimenko, Yury and Courtine, Grégoire and Zhong, Hui and Roy, Roland R. and Edgerton, V. Reggie (2008) Epidural Stimulation Induced Modulation of Spinal Locomotor Networks in Adult Spinal Rats. Journal of Neuroscience, 28 (23). pp. 6022-6029. ISSN 0270-6474. http://resolver.caltech.edu/CaltechAUTHORS:LAVjns08a

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Abstract

The importance of the in vivo dynamic nature of the circuitries within the spinal cord that generate locomotion is becoming increasingly evident. We examined the characteristics of hindlimb EMG activity evoked in response to epidural stimulation at the S1 spinal cord segment in complete midthoracic spinal cord-transected rats at different stages of postlesion recovery. A progressive and phase-dependent modulation of monosynaptic (middle) and long-latency (late) stimulation-evoked EMG responses was observed throughout the step cycle. During the first 3 weeks after injury, the amplitude of the middle response was potentiated during the EMG bursts, whereas after 4 weeks, both the middle and late responses were phase-dependently modulated. The middle- and late-response magnitudes were closely linked to the amplitude and duration of the EMG bursts during locomotion facilitated by epidural stimulation. The optimum stimulation frequency that maintained consistent activity of the long-latency responses ranged from 40 to 60 Hz, whereas the short-latency responses were consistent from 5 to 130 Hz. These data demonstrate that both middle and late evoked potentials within a motor pool are strictly gated during in vivo bipedal stepping as a function of the general excitability of the motor pool and, thus, as a function of the phase of the step cycle. These data demonstrate that spinal cord epidural stimulation can facilitate locomotion in a time-dependent manner after lesion. The long-latency responses to epidural stimulation are correlated with the recovery of weight-bearing bipedal locomotion and may reflect activation of interneuronal central pattern-generating circuits.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1523/JNEUROSCI.0080-08.2008DOIUNSPECIFIED
http://www.jneurosci.org/cgi/content/abstract/28/23/6022PublisherUNSPECIFIED
Additional Information:Copyright © 2008 Society for Neuroscience. Received Jan. 8, 2008; revised April 28, 2008; accepted May 2, 2008. This work was supported by National Institutes of Health Grant NS16333, Russian Foundation for Basic Research –U.S. Civilian Research and Development Foundation Grant 07-04-91106, and the Christopher Reeve Paralysis Foundation (Spinal Cord Consortium, Springfield, NJ). We thank Sharon Zdunowski for help with technical assistance and constructive comments and Maynor Herrera for excellent animal care. The authors declare no competing financial interests.
Funders:
Funding AgencyGrant Number
National Institutes of HealthNS16333
Russian Foundation for Basic Research-U.S. Civilian Research and Development Foundation07-04-91106
Christopher Reeve Paralysis Foundation (Spinal Cord Consortium, Springfield, NJ)UNSPECIFIED
Subject Keywords:CPG; spinal cord stimulation; locomotion; spinal cord; spinal cord injury; synaptic plasticity
Issue or Number:23
Record Number:CaltechAUTHORS:LAVjns08a
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:LAVjns08a
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11364
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:07 Aug 2008 21:27
Last Modified:20 Mar 2015 18:49

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