The effect of passive eye movement on unit discharge in the superior colliculus of the cat.

The effects of passive eye rotation on unit discharge in the superior colliculus has been examined in the chloralose anaesthetized cat. Providing that velocity exceeded 50 degrees/sec, passive eye movement led to brief-burst discharges in the superior colliculus. This discharge occurred as the eye traversed a fixed point. The displacement of this point from the primary position has been defined as the displacement threshold for that unit. Displacement thresholds range from 3 to 30 degrees and are consistent over a wide range of velocities but become larger at the velocity threshold for the unit. Conduction times to the superior colliculus ranged from 7 to 108 msec.