Reciprocal inhibition between motor neurons of the tibialis anterior and triceps surae in humans

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Title: Reciprocal inhibition between motor neurons of the tibialis anterior and triceps surae in humans
Author(s): Yavuz, US
Negro, F
Diedrichs, R
Farina, D
Item Type: Journal Article
Abstract: Motor neurons innervating antagonist muscles receive reciprocal inhibitory afferent inputs to facilitate the joint movement in the two directions. The present study investigates the mutual transmission of reciprocal inhibitory afferent inputs between the tibialis anterior (TA) and triceps surae (soleus and medial gastrocnemius) motor units. We assessed this mutual mechanism in large populations of motor units for building a statistical distribution of the inhibition amplitudes during standardized input to the motor neuron pools to minimize the effect of modulatory pathways. Single motor unit activities were identified using high-density surface electromyography (HDsEMG) recorded from the TA, soleus (Sol), and medial gastrocnemius (GM) muscles during isometric dorsi- and plantarflexion. Reciprocal inhibition on the antagonist muscle was elicited by electrical stimulation of the tibial (TN) or common peroneal nerves (CPN). The probability density distributions of reflex strength for each muscle were estimated to examine the strength of mutual transmission of reciprocal inhibitory input. The results showed that the strength of reciprocal inhibition in the TA motor units was fourfold greater than for the GM and the Sol motor units. This suggests an asymmetric transmission of reciprocal inhibition between ankle extensor and flexor muscles. This asymmetry cannot be explained by differences in motor unit type composition between the investigated muscles since we sampled low-threshold motor units in all cases. Therefore, the differences observed for the strength of inhibition are presumably due to a differential reciprocal spindle afferent input and the relative contribution of nonreciprocal inhibitory pathways.
Publication Date: 1-May-2018
Date of Acceptance: 24-Jan-2018
URI: http://hdl.handle.net/10044/1/56591
DOI: https://dx.doi.org/10.1152/jn.00424.2017
ISSN: 0022-3077
Publisher: American Physiological Society
Start Page: 1699
End Page: 1706
Journal / Book Title: Journal of Neurophysiology
Volume: 119
Issue: 5
Copyright Statement: © 2018 the American Physiological Society
Keywords: high-density EMG
reciprocal inhibition
single motor unit
synaptic distribution
11 Medical And Health Sciences
17 Psychology And Cognitive Sciences
Neurology & Neurosurgery
Publication Status: Published
Embargo Date: 2019-05-01
Online Publication Date: 2018-05-01
Appears in Collections:Faculty of Engineering
Bioengineering



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