Institution: University of California Berkeley
Talk Title: Learning to hold the eyes still and aligned
Abstract: Most common eye movement defects involve either not being able to align the eyes, strabismus, or not being able to hold them still, nystagmus. Superficially, these two symptoms appear unrelated, with strabismus arising from a failure to control eye position to reduce retinal disparity, and nystagmus arising from a failure to control eye velocity to reduce retinal motion. However, many patients suffer from both, highlighting the relevance of mechanisms linking velocity and position control. One potential link appears in the areas of the brain that mathematically convert eye velocity commands into eye position signals. This distributed brain circuit is called the ocular motor integrator (integrator for simplicity). We take advantage of one paradigm of integrator adaptation known as rebound nystagmu (RN). RN occurs in straight ahead gaze after a sustaining eccentric gazing position for about 30 seconds or more. The slow phase or drift of RN is directed toward the previously held eccentric eye position. We will show results of experiments showing how the integrator adapts differently its velocity or position state as well as in horizontal or vertical dimensions. In the future we plan to compare the adaptation to holding eccentric gaze to another phenomenon known as Phoria adaptation that involves adapting to looking at different distances. Understanding how the brain learns to hold the eyes stable and aligned is critical to understanding those different causes, diagnosing them, and developing treatments for them.