The contribution of cranial-nerve nuclei to the short latency vestibular evoked potentials in cat.

The object of this study was to assess the contributions of various cranial nerve nuclei to the short latency vestibular evoked potentials (VsEPs) in cat. The following nuclei were investigated: vestibular nuclei, and 3rd, 6th and 10th cranial nerve nuclei. In unilateral labyrinthectomized cats, suboccipital craniectomy and partial cerebellectomy were carried out in order to place bipolar electrodes into the neural structures under investigation. The surface recorded VsEPs (far-field) were compared with the potentials recorded intracranially in response to the same acceleration impulses. The exact locations were later confirmed histologically. Reversible lesions also were induced by injecting of lignocaine 2%. The results indicate that the 2nd wave (P2) is mainly generated in the superior and medial vestibular nuclei. The 3rd, 6th and 10th cranial nerve nuclei apparently contribute to the later waves of the VsEPs, particularly P3 and P4.