[Oculomotor control by cerebellar flocculus studied in the monkey].

137 unitary activities were recorded from cerebellar flocculus of two pig-tail monkeys; 40 being Purkinje neurons and 81 being mossy fiber activities. Discharge patterns of these unitary activities were modulated accompanying to saccade in the dark. 11 Purkinje neurons stopped the discharge and 3 neurons and 26 mossy fibers showed burst discharges. The monkey was trained to fixate a target; 19 mossy fibers responded to the whole background sinusoidal movement, and 18 mossy fibers responded to passive head rotation. 15 mossy fibers responded to smooth target pursuit movement. 2 Purkinje neurons responded to eye position, 4 neurons responded to eye movement velocity. Responses of 3 Purkinje neurons correspond to sum of the velocity of the eye and head movements. 10 neurons respond to both position and velocity of the eye movement; response phase of 9 out of the 10 neurons changed according to the phase of the sinusoidal pursuit eye movement. The experimental results suggest that the Purkinje neurons in cerebellar flocculus of the monkey send informations concerning eye position, eye movement velocity and head movement velocity to the brain stem, thus functioning as a part of the oculomotor control system.