Oculomotor corollary discharge in the cat pretectum.

Unit activity bursting after the onset of spontaneous eye movements made in total darkness has been recorded from the nucleus of the optic tract (NOT) of the cat pretectum. The present experiments are aimed at determining the functional significance of these neuronal reactions, namely whether the NOT discharge results from an afferent input arising from eye muscle proprioceptors or from a central signal (corollary discharge or efference copy). The results point to a central, rather than a peripheral, origin for NOT discharge. After both eyes have been paralysed, and therefore after eye-muscle proprioceptive input has been removed, NOT activity remained time-locked with increased activity in motoneurons of the III nerve nucleus.