Unilateral stimulation of peripheral vestibular nerve branches in encephale isolé cats evoked potentials of 3- to 7-msec latency in the banks of the contralateral anterior suprasylvian sulcus and 4- to 15-msec latency in the head of the caudate nucleus bilaterally. The responses were distributed in the dorsomedial region of the ipsilateral caudate and dorsolateral region of the contralateral caudate. Stimulation of peripheral cochlear nerve branches also evoked responses in areas of caudate partially overlapping those responsive to vestibular stimulation. Stimulation of the vestibular projection area of cortex evoked a response in caudate but did not alter the response to vestibular nerve stimulation. Ablation of the vestibular projection area of cortex did not alter the vestibular responses in caudate. However, caudate and cortical responses to vestibular nerve stimulation were severely decreased by lesions of the magnocellular portion of medial geniculate body. We conclude that there are vestibular projections to the caudate nuclei which require passage through the medial geniculate body and probably other thalamic nuclei, but not through the vestibular projection area of cortex.
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A number of investigators have proposed that there is an important relationship between the vestibular system and the basal ganglia. Using the Marchi technique, Muskens (19) traced a pathway from the vestibular nuclei to the globus pallidus. From the observation that lesions at various 1 This work has been supported by the clinical research center for Parkinson’s and allied diseases NS 05184 and by the Dutch Organization for Pure Scientific Research (Z.W.O.). Travel funds for Dr. Potegal were provided by IBRO/UNESCO. Present address of Dr. Potegal is : New York State Psychiatric Institute, Department of Behavioral Physiology, 722 West 168th Street, New York, New York. That of Dr. Krauthamer is: Department of Anatomy, Rutgers Medical College, New Brunswick, New Jersey. Reprint requests to Dr. S. Gilman, Department of Neurology, Columbia University, 630 West 16&h Street, New York, N.Y. 10032. We thank Mrs. Madeline Kendeffy, Mrs. Virginia Cordero, and Mr. Jake Bosman for the preparation of histological sections, and also Dr. Luis Marco for his valuable advice and assistance.