The role of ocular proprioception in prism adaptation

Reaching toward a visual target displaced by laterally refracting prisms results in adaptation of limb and ocular proprioception, which individually and additively lead to prism adaptation (PA). The recalibration of oculomotor corollary discharge signals, from which orbito-ocular straight-ahead is derived, displaces perception of visual straight-ahead. The contribution of ocular proprioception to PA has not yet been directly measured. This research will be the first to utilise eye-tracking technology to measure eye position before, during, and after PA, and to compare those measures with a condition where eye muscle potentiation occurs in the absence of visual error feedback. Additionally, it will be the first study to correlate ocular proprioceptive changes with traditional PA after-effect measures of straight-ahead pointing (limb proprioception), open-loop pointing, and dual-limb passive proprioceptive pointing in both conditions. We found that visual adaptation does not occur in patients with lesions of intraparietal cortex. We therefore hypothesise that calibration of ocular proprioception with oculomotor corollary discharge in this brain region is used in computing visual straight ahead. With this novel work, we aim to better understand the role of ocular proprioception in the rehabilitative application of PA.