前半規管から入力を受ける興奮性前庭神経核細胞の中・間脳への軸索投射

抄録

The axonal projections of 34 anterior canal (AC)-activated excitatory secondary vestibular neurons to the mesodiencephalon were studied electrophysiologically in cats. AC-related neurons were identified by monosynaptic activation elicited by electrical stimulation of the vestibular nerve and activation following nose-down rotation of the animal's head. Single excitatory neurons were identified by antidromic activation following electrical stimulation of the contralateral medial longitudinal fasciculus and oculomotor nucleus. The axonal projections of the identified neurons were then studied by systematic, antidromic stimulation of the mesodiencephalon. Ten of the 34 AC-related excitatory neurons were antidromically activated from the superior rectus (SR) subdivision of the oculomotor nucleus, central gray, interstitial nucleus of Cajal, dorsomedial part of Forel's field H and ventrobasal complex of the thalamus. In three other AC neurons, antidromic activation was examined only for the INC, but not for the thalamus. In the remaining 21 AC neurons, antidromic activation was obtained from the SR subdivision, but not from more rostral areas. These results suggest that AC-related excitatory neurons give off axon collaterals to the premotor areas to generate vertical eye movements and the thalamus concerning perception of vestibular sensation.