The Postsaccadic Unreliability of Gain Fields Renders It Unlikely that the Motor System Can Use Them to Calculate Target Position in Space

Gain fields, the eye-position modulation of visual responses, are thought to provide a mechanism by which the motor system can accurately calculate target position in space despite a constantly moving eye. Current gain-field models assume that the modulation of visual responses by eye position is accurate at all times, even around the time of a saccade. Here, we show that for at least 150 ms after a saccade, gain fields in the lateral intraparietal area (LIP) are unreliable. The majority of LIP cells with steady-state gain fields reflect the presaccadic eye position. The remainder of the cells have responses that cannot be predicted by their steady-state gain fields. Nonetheless, a monkey's oculomotor performance is accurate during this time. These results suggest that current models built upon a simple gain-field algorithm cannot be used to calculate the position of a target in space that flashes briefly after a saccade.