Compensatory eye and head movements generated by the cat following stimulation-induced perturbations in gaze position.

It is thought that saccades are controlled by signals representing target and instantaneous eye positions coded with respect to the head. To determine the frame of reference relevant to gaze (= eye + head) control, we extended to the cat whose head is unrestrained the original study of Mays and Sparks (Mays and Sparks 1980). We stimulated the superior colliculus (SC) to perturb initial gaze position before the onset of a gaze shift made in the dark to a flashed target. Gaze shifts compensated for this perturbation and reached the target with normal accuracy, despite the absence of visual feedback. This result indicates that gaze shifts were coded in either a body-centered or spatial frame but we could not distinguish between these two alternatives because the cat's body was fixed.