Otolith processing in the deep cerebellar nuclei.
To investigate the otolith contribution to the responses of "vestibular only" neurons in the rostral fastigial nucleus (FN), single-unit activity was recorded in the alert monkey with the head fixed during static and dynamic stimulation (+/- 15 deg, 0.06-1.4 Hz) around an earth-fixed horizontal axis. Head orientation could be altered allowing for roll, pitch, and intermediate planes of orientation. For the vast majority of neurons a response vector orientation (RVO) with an optimal response and a null-response at a head orientation 90 deg apart could be determined. Presumably more than 30% of the vestibular only neurons had an otolith input, as indicated by responses to static tilt, head-position-related activity, large phase changes (> 100 deg) of neuronal activity between 0.06 and 1.4 Hz, changes of the RVO at different frequencies and complex responses (spatio-temporal convergence). Thus, neurons in FN reflecting an otolith or a combined canal-otolith input are much more common than up to now thought. Vestibular-only neurons are most likely involved in vestibulospinal mechanisms. Their precise functional role has yet to be determined.
Büttner
U
U
Department of Neurology, Ludwig Maximilians University, Munich, Germany. ubuettner@brain.nefo.med.uni-muenchen.de
Glasauer
S
S
Glonti
L
L
Kleine
J F
JF
Siebold
C
C
D000818:Animals; D002529:Cerebellar Nuclei / Q000166:cytology / Q000502:physiology*; D004558:Electric Stimulation; D004594:Electrophysiology; D008253:Macaca mulatta; D009474:Neurons / Q000502:physiology; D009949:Orientation / Q000502:physiology; D010037:Otolithic Membrane / Q000502:physiology*; D014722:Vestibule, Labyrinth / Q000166:cytology / Q000502:physiology