The Neural Mechanism of Saccade Motor Learning

Abstract

Saccadic eye movements bring the image of a visual target onto the fovea. Because of the small size of the fovea, saccades must be accurate, and in fact they are. Their accuracy is maintained by a motor learning mechanism called saccade adaptation, which is driven by visual information about movement error. The McLaughlin paradigm, which creates artificial movement error, has proven to be a valuable experimental tool for inducing adaptation and has revealed various aspects of saccade adaptation. Most importantly, the cerebellar oculomotor vermis has been implicated as a site of saccade plasticity. However, little is known about the neural signal that drives and guides motor learning in voluntary movements, including saccades. This review first summarizes our current knowledge regarding saccade adaptation, then describes the authors’ recent research on the induction of adaptation by electrical stimulation of the midbrain superior colliculus. Long known to be a structure that generates saccade motor commands, the superior colliculus is now suggested to be a brainstem origin of a neural signal that drives saccade motor learning.