Abstract

This was aimed at evaluating electrophysiological properties of vestibular evoked potentials (VEp) from the brain stem slice using multi-site extracellular recording system. VEp was induced by single stimulation of the vestibular nerve located at in lateral border of medial vestibular nucleus of the brain stem slice. Sixty-four hannels extracellular recording system was adopted to record VEp. VEp composing one (N1) or two negative waves (N1, N2) was easily recorded in the medial vestibular nucleus within about 1 mm from stimulation site. In some case VEp was likely to spread whole area of in the medial vestibular nucleus by giving one point stimulation of the vestibular nerve. However other vestibular nuclei except for medial vestibular nuclei showed no VEp by stimulation of the vestibular nerve. Application of calcium-free aCSF markedly suppressed amplitude of VEp and delayed latency. A brief treatment of glutamate gave rise to a significant long-term increase in amplitude of VEp. On the other hand pretreatment of glutamate receptor antagonists blocked glutamate-induced potentiation of VEp. Therefore these results suggest that multi-site extracellular recording system will be more useful tool for studying vestibular neurophysiology than conventional single extracellular recording system (This study was supported by a grant of Vestibulocochlear Research Center from the Ministry of Science and Engineering).