The long range aim of this project is to determine the neural basis of adaptive mechanisms responsible for maintaining appropriate performance levels in the oculomotor system. One project is concerned with localizing the modifiable elements subserving long-term regulation of the gain of the vestibulo-ocular reflex. Single unit recordings in the vestibulo-ocular pathways of awake monkeys have revealed that the underlying modifications must occur beyond the first synapse in the medial vestibular nuclei. The second project is concerned with the mechanisms by which the static (step) component of saccadic eye movements is appropriately matched to the dynamic (pulse) component to insure stable vision following such eye movements. By recording eye movements and shifting the visual scene after each saccade, it has been shown that persistent post-saccadic retinal image slip is sufficient to induce pulse-step mismatch, suggesting an important role for visual inputs in this adaptive process.