VESTIBULAR AND VISUAL CONTROL OF EYE MOVEMENT

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The vestibulo-ocular reflex (VOR) reduces motion of visual images on the retina by evoking eye movements in the opposite direction to head movements. A form of motor learning, known as VOR adaptation, calibrates the VOR by gradually correcting the reflex when image motion is persistently associated with head turns. VOR adaptation is essential for ensuring adequate visual acuity during head turns and for restoring proper motor and perceptual orientation in space in response to changes in the organism or its environment, such as occur with growth and development, aging, injury to the peripheral or central nervous system, the donning of a new pair of spectacles, or travel in space. The proposed experiments examine the neural mechanisms of VOR adaptation by asking the following questions: How do the parameters of visual-vestibular stimulation (image motion during head turns) affect VOR adaptation? (Aim 1) What patterns of neural signals are consistently present during stimuli that induce VOR adaptation, and might therefore serve as the neural trigger for VOR adaptation? (Aim 2) How might plasticity in neural pathways through the cerebellum contribute to VOR adaptation? (Aim 3) The VOR is one of many motor systems that is thought to rely on cerebellum-dependent learning to maintain normal sensorimotor function and for recovery of function following injury. The anatomy and physiology of the cerebellum is very regular across the extent of this structure, therefore, the principles uncovered in studies of VOR adaptation may be useful for the development of rational therapeutic approaches to many forms of sensorimotor dysfunction.