Responses of cerebellar fastigial neurons to stimulation of contralateral macular labyrinthine receptors
Erway, L.C.; Ghelarducci, B.; Pompeiano, O.; Stanojević, M.
Archives Italiennes de Biologie 116(2): 205-224
1978
ISSN/ISBN: 0003-9829 PMID: 686945 Document Number: 131945
Experiments were performed in decerebrate cats with complete section of right VIII nerve, to determine whether neurons recorded from the right fastigial nucleus responded to stimulation of the contralateral labyrinth. Among 81 fastigial units tested, 47 units showed positional responses during 20.degree. tilt in one or in both directions of the median plane, which would be expected to activate the contralateral macular labyrinthine receptors. Of units affected by tilt, 87.2% were also influenced by stimulation of neck (and forelimb nerve) afferents of both sides; 4.3% of the units affected by tilt were influenced only by the somatic input from the forelimbs, but not by the neck input, while only 8.5% of the units affected by tilt were influenced neither by neck muscle afferents, nor by forelimb nerve stimulation. The responses to tilt of individual units located in the rostral part of the right fastigial nucleus ipsilateral to the side of the labyrinthine deafferentation were still present after complete parasagittal section of the cerebellum which interrupted all the crossed vestibulocerebellar afferents activated by the intact labyrinth. Only 7 of 61 fastigial units responded to tilt. This finding indicates that the crossed vestibulocerebellar projection to the fastigial nucleus represents the main, although not the exclusive pathway, transmitting the macular labyrinthine input to the contralateral fastigial nucleus. The importance of this crossed labyrinthine mechanism in the control of posture was discussed.