Role of the spinocerebellum in adaptive gain control of cat's vestibulospinal reflex.
In decerebrate cats, a 3-h period of sustained roll tilt of the head (at 0.15 Hz. +/- 10) leading to selective stimulation of labyrinth receptors, associated with a synchronous roll tilt of the body (at 0.15 Hz., +/- 12.5) leading to 2.5 degrees out-of-phase neck rotation produced an adaptive increase in gain of the vestibulospinal reflex (VSR) elicited by roll tilt of the animal at 0.15 Hz, +/- 10 degrees. This increase reached the maximum at the end of the third h of stimulation and persisted unmodified during the first h after stimulation. Microinjection into zone B of the cerebellar anterior vermis of the GABA-A agonist muscimol (0.25 microliter at 8 micrograms/microliters saline), producing only a slight or negligible depression of the VRS gain in non-adaptive conditions, prevented the occurrence of the adapted increase in gain of the VSR following a 3-h period of sustained head-body rotation. Moreover, intravermal injection of the GABA-A agonist muscimol or the GABA-B agonist baclofen (0.25 microliter at 8 or 2 micrograms/microliters saline, respectively) suppressed the already adapted VSR gain. It is postulated that the adaptive increase in gain of the VSR following a sustained neck-vestibular stimulation depends on plastic changes which affect the Purkinje cells of the cerebellar anterior vermis.
Pompeiano
O
O
Department of Physiology and Biochemistry, University of Pisa, Italy.
Andre
P
P
D'Ascanio
P
P
Manzoni
D
D
D000818:Animals; D002415:Cats; D002525:Cerebellar Cortex / Q000502:physiology; D002531:Cerebellum / Q000502:physiology*; D009334:Neck Muscles / Q000294:innervation; D009434:Neural Pathways / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology*; D009949:Orientation / Q000502:physiology*; D004856:Postural Balance / Q000502:physiology*; D011187:Posture / Q000502:physiology; D011689:Purkinje Cells / Q000502:physiology*; D011963:Receptors, GABA-A / Q000502:physiology; D018080:Receptors, GABA-B / Q000502:physiology; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology*; D013116:Spinal Cord / Q000502:physiology*; D014725:Vestibular Nerve / Q000502:physiology*
D011963:Receptors, GABA-A; D018080:Receptors, GABA-B