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Sub-threshold spinal cord stimulation facilitates spontaneous motor activity in spinal rats.

Gad P, Choe J, Shah P, Garcia-Alias G, Rath M, Gerasimenko Y, Zhong H, Roy RR, Edgerton VR - J Neuroeng Rehabil (2013)

Bottom Line: Spontaneous cage activity was recorded using a specially designed swivel connector to record EMG signals and an IR based camcorder to record video.In contrast, with eEmc the rats were highly active and the hindlimbs showed robust alternating flexion and extension resulting in step-like movements during forelimb-facilitated locomotion and often would stand using the sides of the cages as support.The mean and summed integrated EMG levels in both a hindlimb flexor and extensor muscle were higher with than without eEmc.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Integrative Biology and Physiology, University of California, Los Angeles, Terasaki Life Sciences Building, 610 Charles E, Young Drive East, Los Angeles, CA 90095-7239, USA. vre@ucla.edu.

ABSTRACT

Background: Epidural stimulation of the spinal cord can be used to enable stepping on a treadmill (electrical enabling motor control, eEmc) after a complete mid-thoracic spinal cord transection in adult rats. Herein we have studied the effects of eEmc using a sub-threshold intensity of stimulation combined with spontaneous load-bearing proprioception to facilitate hindlimb stepping and standing during daily cage activity in paralyzed rats.

Methods: We hypothesized that eEmc combined with spontaneous cage activity would greatly increase the frequency and level of activation of the locomotor circuits in paralyzed rats. Spontaneous cage activity was recorded using a specially designed swivel connector to record EMG signals and an IR based camcorder to record video.

Results and conclusion: The spinal rats initially were very lethargic in their cages showing little movement. Without eEmc, the rats remained rather inactive with the torso rarely being elevated from the cage floor. When the rats used their forelimbs to move, the hindlimbs were extended and dragged behind with little or no flexion. In contrast, with eEmc the rats were highly active and the hindlimbs showed robust alternating flexion and extension resulting in step-like movements during forelimb-facilitated locomotion and often would stand using the sides of the cages as support. The mean and summed integrated EMG levels in both a hindlimb flexor and extensor muscle were higher with than without eEmc. These data suggest that eEmc, in combination with the associated proprioceptive input, can modulate the spinal networks to significantly amplify the amount and robustness of spontaneous motor activity in paralyzed rats.

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Representative EMG and evoked potentials with and without eEmc. Representative raw EMG and evoked potentials from the soleus and tibialis anterior (TA) muscles without eEmc from one spinal rat during (A) sitting, (B) attempted bipedal standing, and with eEmc (1.5 V, 40 Hz between L2 and S1) during (C) sitting, (D) bipedal standing, and (E) quadrupedal (Quad) stepping-like movement during the 6-hr recording period in its home cage. (F) Representative EMG and evoked potential from the soleus and TA from the same rat during body weight supported bipedal treadmill stepping facilitated by eEmc (2.0 V, 40 Hz between L2 and S1). The start of each trace with eEmc is synchronized with the initiation of the eEmc pulse. Each trace is 25 msec, i.e., the time between successive eEmc pulses. The arrow placed on the EMG signals denotes the time of the initial 25 msec scan.
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Figure 1: Representative EMG and evoked potentials with and without eEmc. Representative raw EMG and evoked potentials from the soleus and tibialis anterior (TA) muscles without eEmc from one spinal rat during (A) sitting, (B) attempted bipedal standing, and with eEmc (1.5 V, 40 Hz between L2 and S1) during (C) sitting, (D) bipedal standing, and (E) quadrupedal (Quad) stepping-like movement during the 6-hr recording period in its home cage. (F) Representative EMG and evoked potential from the soleus and TA from the same rat during body weight supported bipedal treadmill stepping facilitated by eEmc (2.0 V, 40 Hz between L2 and S1). The start of each trace with eEmc is synchronized with the initiation of the eEmc pulse. Each trace is 25 msec, i.e., the time between successive eEmc pulses. The arrow placed on the EMG signals denotes the time of the initial 25 msec scan.

Mentions: We carefully examined the relationship between the absence or presence of eEmc and the amount and pattern of spontaneous cage activity. In the absence of eEmc there were periods of spontaneous activity when the rats remained in a sitting posture (Figure 1A) and on some occasions when it appeared that they were attempting to stand (Figure 1B) (Additional file1: Video 1). EMG activity increased, particularly in the soleus, during incidences of apparent attempted standing (Figure 1B). The most common observed position was for the rats to have their hindlimbs completely extended often showing little or no movement except some spastic-like reactions. Even during movement propelled by the forelimbs, the upper body remained low with the head close to the floor of the cage and the hindlimbs extended.


Sub-threshold spinal cord stimulation facilitates spontaneous motor activity in spinal rats.

Gad P, Choe J, Shah P, Garcia-Alias G, Rath M, Gerasimenko Y, Zhong H, Roy RR, Edgerton VR - J Neuroeng Rehabil (2013)

Representative EMG and evoked potentials with and without eEmc. Representative raw EMG and evoked potentials from the soleus and tibialis anterior (TA) muscles without eEmc from one spinal rat during (A) sitting, (B) attempted bipedal standing, and with eEmc (1.5 V, 40 Hz between L2 and S1) during (C) sitting, (D) bipedal standing, and (E) quadrupedal (Quad) stepping-like movement during the 6-hr recording period in its home cage. (F) Representative EMG and evoked potential from the soleus and TA from the same rat during body weight supported bipedal treadmill stepping facilitated by eEmc (2.0 V, 40 Hz between L2 and S1). The start of each trace with eEmc is synchronized with the initiation of the eEmc pulse. Each trace is 25 msec, i.e., the time between successive eEmc pulses. The arrow placed on the EMG signals denotes the time of the initial 25 msec scan.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4016220&req=5

Figure 1: Representative EMG and evoked potentials with and without eEmc. Representative raw EMG and evoked potentials from the soleus and tibialis anterior (TA) muscles without eEmc from one spinal rat during (A) sitting, (B) attempted bipedal standing, and with eEmc (1.5 V, 40 Hz between L2 and S1) during (C) sitting, (D) bipedal standing, and (E) quadrupedal (Quad) stepping-like movement during the 6-hr recording period in its home cage. (F) Representative EMG and evoked potential from the soleus and TA from the same rat during body weight supported bipedal treadmill stepping facilitated by eEmc (2.0 V, 40 Hz between L2 and S1). The start of each trace with eEmc is synchronized with the initiation of the eEmc pulse. Each trace is 25 msec, i.e., the time between successive eEmc pulses. The arrow placed on the EMG signals denotes the time of the initial 25 msec scan.
Mentions: We carefully examined the relationship between the absence or presence of eEmc and the amount and pattern of spontaneous cage activity. In the absence of eEmc there were periods of spontaneous activity when the rats remained in a sitting posture (Figure 1A) and on some occasions when it appeared that they were attempting to stand (Figure 1B) (Additional file1: Video 1). EMG activity increased, particularly in the soleus, during incidences of apparent attempted standing (Figure 1B). The most common observed position was for the rats to have their hindlimbs completely extended often showing little or no movement except some spastic-like reactions. Even during movement propelled by the forelimbs, the upper body remained low with the head close to the floor of the cage and the hindlimbs extended.

Bottom Line: Spontaneous cage activity was recorded using a specially designed swivel connector to record EMG signals and an IR based camcorder to record video.In contrast, with eEmc the rats were highly active and the hindlimbs showed robust alternating flexion and extension resulting in step-like movements during forelimb-facilitated locomotion and often would stand using the sides of the cages as support.The mean and summed integrated EMG levels in both a hindlimb flexor and extensor muscle were higher with than without eEmc.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Integrative Biology and Physiology, University of California, Los Angeles, Terasaki Life Sciences Building, 610 Charles E, Young Drive East, Los Angeles, CA 90095-7239, USA. vre@ucla.edu.

ABSTRACT

Background: Epidural stimulation of the spinal cord can be used to enable stepping on a treadmill (electrical enabling motor control, eEmc) after a complete mid-thoracic spinal cord transection in adult rats. Herein we have studied the effects of eEmc using a sub-threshold intensity of stimulation combined with spontaneous load-bearing proprioception to facilitate hindlimb stepping and standing during daily cage activity in paralyzed rats.

Methods: We hypothesized that eEmc combined with spontaneous cage activity would greatly increase the frequency and level of activation of the locomotor circuits in paralyzed rats. Spontaneous cage activity was recorded using a specially designed swivel connector to record EMG signals and an IR based camcorder to record video.

Results and conclusion: The spinal rats initially were very lethargic in their cages showing little movement. Without eEmc, the rats remained rather inactive with the torso rarely being elevated from the cage floor. When the rats used their forelimbs to move, the hindlimbs were extended and dragged behind with little or no flexion. In contrast, with eEmc the rats were highly active and the hindlimbs showed robust alternating flexion and extension resulting in step-like movements during forelimb-facilitated locomotion and often would stand using the sides of the cages as support. The mean and summed integrated EMG levels in both a hindlimb flexor and extensor muscle were higher with than without eEmc. These data suggest that eEmc, in combination with the associated proprioceptive input, can modulate the spinal networks to significantly amplify the amount and robustness of spontaneous motor activity in paralyzed rats.

Show MeSH
Related in: MedlinePlus