EXTRAOCULAR-MUSCLE PROPRIOCEPTION FUNCTIONS IN THE CONTROL OF OCULAR ALIGNMENT AND EYE-MOVEMENT CONJUGACY

1. The function of extraocular muscle proprioception in the control of eye movements is uncertain. We tested the hypothesis that propriocept ion contributes to the long-term regulation of ocular alignment and ey e movement conjugacy. 2. Eye movements were recorded in monkeys with u nilateral extraocular muscle palsies, before and after proprioceptive deafferentation of the paretic eye. Following deafferentation, ocular alignment and saccade conjugacy gradually worsened over several weeks. In contrast, disconjugate adaptation induced by habitual binocular vi ewing with a prism (disparity-mediated adaptation) occurred normally a fter deafferentation. 3. These results provide the first evidence that proprioception functions in the control of eye movements in primates, and indicate that proprioception contributes to the long-term adaptiv e mechanisms that regulate ocular alignment during fixation and saccad es. The error signal used in this process may be derived from a mismat ch between the efference copy and proprioceptive afference.