Blink-induced saccadic oscillations.

A patient with a neurodegenerative disease had abnormal saccades only when he blinked. These saccades were hypermetric and were followed immediately, without any intersaccadic interval, by a large, oppositely directed saccade (dynamic overshoot). To explain these findings, we hypothesize that a blink-related neural signal can modulate the activity of pause cells that normally inhibit saccadic burst neurons during fixation. In pathological circumstances, abnormal function of pause cells could lead to large-amplitude saccadic oscillations. In normal subjects, blinks could induce short bursts of low-amplitude flutter.