ABLATION OF THE PURSUIT AREA IN THE FRONTAL-CORTEX OF THE PRIMATE DEGRADES FOVEAL BUT NOT OPTOKINETIC SMOOTH EYE-MOVEMENTS

1. Neural pathology which impairs foveal smooth pursuit eye movements typically also degrades optokinetic pursuit of large textures, suggest ing that the two kinds of pursuit share a common circuit. This study r eports an exception. After sequential bilateral ablation of the pursui t area in the frontal lobe three monkeys displayed degraded pursuit of a small foveal target but performed normally on identical measures of optokinetic pursuit. 2. A related experiment in one subject demonstra ted a pursuit deficit when the foveal target moved relative to the bac kground, but not when background and target moved together. The fronta l pursuit area may specifically control pursuit of relative motion, an d do so by receiving signals primarily from motion detectors in the ma cular part of the visual field.