Recruitment gain of spinal motor neuron pools in cat and human.
Recruitment gain of spinal motor neuron pools in cat and human.
Exp Brain Res. 2019 Sep 06;:
Authors: Nielsen JB, Morita H, Wenzelburger R, Deuschl G, Gossard JP, Hultborn H
Abstract
The output from a motor nucleus is determined by the synaptic input to the motor neurons and their intrinsic properties. Here, we explore whether the source of synaptic inputs to the motor neurons (cats) and the age or post-stroke conditions (humans) may change the recruitment gain of the motor neuron pool. In cats, the size of Ia EPSPs in triceps surae motor neurons (input) and monosynaptic reflexes (MSRs; output) was recorded in the soleus and medial gastrocnemius motor nerves following graded stimulation of dorsal roots. The MSR was plotted against the EPSP thereby obtaining a measure of the recruitment gain. Conditioning stimulation of sural and peroneal cutaneous afferents caused significant increase in the recruitment gain of the medial gastrocnemius, but not the soleus motor neuron pool. In humans, the discharge probability of individual soleus motor units (input) and soleus H-reflexes (output) was performed. With graded stimulation of the tibial nerve, the gain of the motor neuron pool was assessed as the slope of the relation between probability of firing and the reflex size. The gain in young subjects was higher than in elderly subjects. The gain in post-stroke survivors was higher than in age-matched neurologically intact subjects. These findi...
Source: Experimental Brain Research - Category: Neuroscience Authors: Nielsen JB, Morita H, Wenzelburger R, Deuschl G, Gossard JP, Hultborn H Tags: Exp Brain Res Source Type: research
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