Cerebellar influences on the response characteristic of vestibulospinal neurons to sinusoidal tilt
Boyle, R.; Pompeiano, O.
Archives Italiennes de Biologie 119(3): 208-225
1981
ISSN/ISBN: 0003-9829 PMID: 7316639 Document Number: 177623
The role of the paleocerebellum in determining the response characteristics of lateral vestibular nucleus (LVN) neurons to sinusoidal rotation around the longitudinal axis of the animal at 0.026 Hz, 100 peak displacement was investigated in decerebrate cats. Among the tested units, 102 and 190 units were recorded in animals with intact cerebellum and following partial cerebellectomy, respectively. The units were located in either the rostroventral (cLVN) or dorsocaudal (ILVN) part of LVN; some units were activated antidromically from the spinal cord. Most units responded to stimulation of macular receptors both in preparations with intact cerebellum (75.5%) or with partial cerebellectomy (64.2%), the 1st harmonic component of response being mainly in phase with the direction of animal orientation. The proportion of responding units, their response gain and sensitivity were greater in the cLVN than lLVN in each preparation; no significant differences in mean firing rate, response gain and sensitivity were observed between the 2 preparations for each subdivision of the LVN. In animals with intact cerebellum most cLVN and lLVN units were excited during side-down and inhibited during side-up tilt (.alpha.-response); following partial cerebellectomy, this predominant response pattern was still present in cLVN, but it was reversed in lLVN (.beta.-response). Changes in phase relation of unit responses were observed within the lLVN, but not within the cLVN. Responses of vestibulospinal neurons projecting to the lumbosacral cord and characterized by a predominant 2nd harmonic component (.gamma.-responses) were observed only in preparations after partial cerebellectomy and during slow sinusoidal tilts. Results are reviewed in terms of the role of the cerebellum in gain regulation and/or phase adjustment of LVN units responses during animal rotation.