Cortical Responses to Rotation I. Responses Recorded after Cessation of Rotation

Abstract

Averaged cortical responses to labyrinthine stimulation induced by sudden cessation of single rotations were studied using a Mnemotron Computer of Average Transients. Following rotation there appeared in cats with the eyelids closed diffuse, slow, sometimes multiphasic responses. They were probably due to excitation of the diffuse thalamic system. In human subjects similar responses could be obtained either diffusely or prevalent or exclusively from the preoccipital and/or parastriate area. The responses observed in posterior parts of the cerebral hemisphere following cessation of rotation appeared also, if the animals were flaxedilized, or the second somatic sensory area was ablated in both hemispheres. Bilateral labyrinthectomy abolished these responses. While the observation of the ocular reactions to labyrinthine stimulation permits one to ascertain the excitability of the vestibulo-ocular reflex arc only, the recording of the cortical responses to rotation may perhaps be developed into a clinical tool for the study of the state of corticopetal systems carrying labyrinthine impulses.