THE VESTIBULAR NUCLEI AS AN EXCITATORY MECHANISM FOR THE CORD

Abstract

Facilitation of cortically or reflexly induced movement, evoked by exciting the brain stem tegmentum and reticular formation in the cat, is still elicitable after destroying the vestibular nuclei or interrupting their descending connections in the cord. Such facilitation, mediated by reticulo-spinal paths, is not obtained by exciting the vestibular nuclei. Earlier observations that injury to the vestibulo-spinal system abolished decerebrate rigidity are confirmed, but it is suggested that the initial elimination of other facilitatory structures is involved, for in cats with spas-ticity from cerebral lesions, and in which the brain is otherwise intact, vestibular nuclear injury does not induce a flaccid state and is without effect upon phasic hyperreflexia.