Neuronal activity in the vestibular nuclei of the alert monkey during vestibular and optokinetic stimulation.

Recordings from neurons of the vestibular nuclei were performed in alert monkeys. Type I and type II units were identified by rotating the monkey about a vertical axis. Al neurons responded also when only the visual surround was rotated around the stationary monkey. The combination of visual and vestibular stimulation points towards non-algebraic summation characteristics for the two inputs, with each input dominating the response over a certain range.