A Dual-Mode Dynamic Model of the Vergence Eye Movement System

The disparity vergence eye movement system, long thought to be a simple continuous feedback system, has recently been shown to exhibit more complex dual-mode slow and fast responses. A model has been developed which simulates this behavior. The slow component accounts for the smooth following of slowly moving stimuli. The fast component has sampling and prediction mechanisms which account for the staircase-like step responses to fast ramp stimuli. Model simulation responses to pulse, step, step-pulse, ramp, and sinusoidal stimuli show good fit to these diverse experimental results. This robust and comprehensive model forms the basis for further understanding of the dynamic controlling mechanisms of the vergence system.