CONTRIBUTION OF THE 8TH NERVE AND CRANIAL NERVE NUCLEI TO THE SHORT-LATENCY VESTIBULAR EVOKED-POTENTIALS IN CATS

The object of this study was to assess the contributions of the vestib ular nerve and various cranial nerve nuclei to the short-latency vesti bular evoked potentials in cat. The following nuclei were investigated : vestibular nuclei and the third, sixth, and tenth cranial nerve nucl ei. In unilateral labyrinthectomized cats, we performed suboccipital c raniectomy and partial cerebellectomy to place bipolar electrodes into the neural structures under investigation. The surface-recorded vesti bular evoked potentials (far field) were compared with the potentials recorded intracranially in response to the same acceleration impulses. The exact locations were later confirmed histologically. Reversible l esions also were induced by injection of lidocaine 2%. The results ind icate that the first wave of the vestibular evoked potentials originat es in the vestibular nerve, and the second wave is mainly generated in the superior and medial vestibular nuclei. The third, sixth, and tent h cranial nerve nuclei apparently contribute to the later waves of the vestibular evoked potentials, particularly waves 3 and 4.