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HIGHLIGHTED TOPICS
Neural Control of Movement

Spinal reciprocal inhibition in human locomotion

¹Centre for Neuroscience, University of Alberta, Edmonton, Alberta, Canada T6G 2S2; ²Department of Rehabilitation Medicine, Keio University School of Medicine, Tokyo 1608582, Japan; and ³Department of Physiology, University of Alberta, Edmonton, Alberta, Canada T6G 2S2

Submitted 1 October 2003 ; accepted in final form 2 December 2003

The purpose of this paper was to study spinal inhibition during several different motor tasks in healthy human subjects. The short-latency, reciprocal inhibitory pathways from the common peroneal (CP) nerve to the soleus muscle and from the tibial nerve to the tibialis anterior muscle were studied as a depression of ongoing voluntary electromyograph (EMG) activity. First, the effect of stimulus intensity on the amount of inhibition was examined to decide an appropriate stimulation to study the task-dependent modulation of inhibition. Then, the inhibition at one level of stimulation (1.5 x motor threshold) was investigated during standing, walking, and running. The change in slope of inhibition vs. EMG level, which approximates the fraction of ongoing activity that is inhibited, decreased with CP stimulation from 0.52 during standing to 0.30 during fast walking (6 km/h) to 0.17 during running at 9 km/h. Similarly, the slope decreased with tibial nerve stimulation from 0.68 (standing) to 0.42 (fast walking) to 0.35 (running at 9 km/h). All differences, except the last one, were highly significant (P < 0.01, Student's t-test). However, the difference between walking (0.42) and running (0.36) at the same speed (6 km/h) was not significant with tibial nerve stimulation and only significant at P < 0.05 with CP nerve stimulation (0.30, 0.20). Also, the difference between standing (0.52) and slow walking (3 km/h; 0.41) with CP stimulation was not significant, but it was significant (P < 0.01) with tibial nerve stimulation (0.68, 0.49). In conclusion, our findings indicate that spinal reciprocal inhibition decreases substantially with increasing speed and only changes to a lesser extent with task.

antagonist muscle nerve stimulation; walking; running

This article has been cited by other articles:

				A. K. Thompson, K. L. Estabrooks, S. Chong, and R. B. Stein Spinal Reflexes in Ankle Flexor and Extensor Muscles After Chronic Central Nervous System Lesions and Functional Electrical Stimulation Neurorehabil Neural Repair, February 1, 2009; 23(2): 133 - 142. [Abstract] [PDF]

				X. Y. Chen, L. Chen, Y. Chen, and J. R. Wolpaw Operant Conditioning of Reciprocal Inhibition in Rat Soleus Muscle J Neurophysiol, October 1, 2006; 96(4): 2144 - 2150. [Abstract] [Full Text] [PDF]

				S. Rossignol, R. Dubuc, and J.-P. Gossard Dynamic Sensorimotor Interactions in Locomotion Physiol Rev, January 1, 2006; 86(1): 89 - 154. [Abstract] [Full Text] [PDF]

				G. Nafati, A. Schmied, and C. Rossi-Durand Changes in the Inhibitory Control Exerted by the Antagonist Ia Afferents on Human Wrist Extensor Motor Units During an Attention-Demanding Motor Task J Neurophysiol, April 1, 2005; 93(4): 2350 - 2353. [Abstract] [Full Text] [PDF]

				G. C. Sieck Commentary J Appl Physiol, May 1, 2004; 96(5): 1968 - 1968. [Full Text] [PDF]