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Inhibitory connections of ipsilateral semicircular canal afferents onto Renshaw cells in the lumbar spinal cord of the cat.
Author(s) -
Ross H G,
Thewissen M
Publication year - 1987
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1987.sp016603
Subject(s) - renshaw cell , stimulation , spinal cord , semicircular canal , inhibitory postsynaptic potential , anatomy , reflex , hindlimb , lumbar spinal cord , neuroscience , vestibular system , proprioception , muscle spindle , lumbar , decerebrate state , medicine , cats , vestibular nerve , anesthesia , biology , electric stimulation , afferent
1. In intercollicularly decerebrate cats, the excitability of lumbar spinal Renshaw cells (tested by single shocks to ventral roots and deafferented muscle nerves) decreased for 600‐1000 ms after conditioning electrical stimulation of ipsilateral semicircular canal nerves. 2. Conditioning stimulation of posterior canal afferents and combined stimulation of anterior and lateral canal afferents were equally effective in causing inhibition of Renshaw cells. No significant differences were observed for Renshaw cells excitable from hind‐limb flexor or extensor nerves. 3. Inhibition appeared when one to five stimuli were applied to the canal afferents and arrived at the spinal segmental level 11‐15 ms after the onset of conditioning stimulation. 4. Evidence is adduced to suggest that the inhibitory effects on Renshaw cells following stimulation of semicircular canal afferents were mediated directly, i.e. they were not caused by alterations of motoneurone activity. 5. Excitation of Renshaw cells due to stimulation of the canal afferents was rarely observed; it could not be excluded that it was secondary to motoneurone discharges. 6. It is suggested that vestibular inhibition of Renshaw cells ensure a high gain of hind‐limb alpha‐motoneurones during postural adjustments following a massive disturbance of body equilibrium.