Abstract
In daily life, smooth pursuit is performed by coordination of eyes and head movements (i.e. gaze pursuit). Previous studies indicate that caudal parts of FEF contain pursuit related neurons and that the majority of them carry gaze velocity signals during passive whole body rotation. However, because these studies were performed in head-fixed conditions, it is unknown whether their signals are related to active gaze pursuit. To dissociate gaze from eye and/or head pursuit, in this study 2 monkeys were trained to move their heads to pursue a reward feeder during eye pursuit of a laser spot while their heads were free to rotate about a vertical axis. As a search task, the feeder and spot moved together at 0.3 Hz (±15°) and the monkeys tracked the feeder and spot by gaze pursuit. Responding neurons were tested for eye pursuit for spot motion while the feeder was stationary and head pursuit for tracking the feeder while the spot was stationary. Of 99 responding neurons in the caudal FEF, the majority (62%) were modulated during gaze, eye and head pursuit similarly. The second group (25%) was modulated during gaze and eye pursuit similarly but only weakly during head pursuit when gaze was stationary. Their activity was similar to passive gaze velocity neurons. A minority of neurons was modulated only during head pursuit with minimal modulation during eye pursuit (8%) or only during gaze pursuit (5%). These results suggest that the majority of FEF pursuit neurons are modulated during both eye and head pursuit. [Jpn J Physiol 55 Suppl:S177 (2005)]
