The effect of afferent signals from extraocular muscles on visual responses of cells in the optic tectum of the pigeon

Abstract

Feedback signals from the muscles that move the eye in the orbit, the extraocular muscles, are generally assumed to play no important role either in visual processing or in oculomotor control. However, we have recently shown that these signals are involved in the vestibular control of eye movement, the vestibuloocular reflex. To investigate whether they might also be involved in visual processing, we have recorded from single units in the primary visual system of the pigeon, in the optic tectum. We demonstrate here that the visual responses of these units can be modified by extraocular muscle afferent signals induced by passive eye movement, and that information concerning the direction and amplitude of eye movement reaches the tectum and interacts with visually responsive units in a directionally selective manner. These results suggest that extraocular muscle afferent signals may be involved in the processing of visual information in the optic tectum of the pigeon.