Adaptive modification of oculomotor pursuit influences manual tracking responses.

We have addressed the question of whether adaptively modifying the oculomotor response to a visual pursuit stimulus has an influence on a related manual tracking response. Subjects used their unseen right hand to track targets moving at constant velocities while visually fixating a stationary LED. Manual tracking performance was compared before and after a 20 min period during which smooth pursuit eye movements alone were adaptively enhanced by adding 50% of the instantaneous eye position signal to target position. Compared with the preadaptation trials, hand gain was markedly increased during the postadaptation period. These results imply that the adaptation occurred at a level common to both motor systems, probably in CNS structures concerned with visual motion processing.