Feedback control of Purkinje cell activity by the cerebello-olivary pathway.
The pathway from the deep cerebellar nuclei to the inferior olive, the source of the climbing fibre input to the cerebellum, inhibits olivary transmission. As climbing fibre activity can depress the background firing of the Purkinje cells, it was suggested that nucleo-olivary (N-O) inhibition is a negative feedback mechanism for regulating Purkinje cell excitability. This suggestion was investigated, in a set-up with decerebrate ferrets, both by blocking and by stimulating cerebellar output while recording Purkinje cell activity. Blocking the N-O pathway was followed by an increased climbing fibre activity and a dramatic reduction in simple spike firing. Stimulation of the N-O fibres depressed climbing fibre responses and caused an increase in simple spike firing. These results are taken as support for the feedback hypothesis.
Bengtsson
F
F
Department of Physiological Sciences, Section for Neurophysiology, BMC F10, S-221 84 Lund, Sweden. fredrik.bengtsson@mphy.lu.se
Svensson
P
P
Hesslow
G
G
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D000344:Afferent Pathways / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D002531:Cerebellum / Q000166:cytology* / Q000502:physiology; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation / Q000379:methods; D005246:Feedback / Q000502:physiology*; D005289:Ferrets; D008012:Lidocaine / Q000494:pharmacology; D008297:Male; D009847:Olivary Nucleus / Q000033:anatomy & histology / Q000502:physiology*; D011689:Purkinje Cells / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
D000779:Anesthetics, Local; D008012:Lidocaine