Complex spike responses of cerebellar Purkinje cells to constant velocity optokinetic stimuli in the cat flocculus.

In the cat cerebellar flocculus without cerebrum but with intact accessory optic tract, complex spike (CS) responses to horizontal optokinetic stimuli (velocity-step at 2 degrees/s) were investigated. The directionally selective CS responses were present only during the short-duration stimuli but not during the continuous unidirectional stimuli. Following the end of the stimuli during the stationary surround phase, the CS activity was modulated in a manner opposite to the preceding CS response during the stimulation. These CS responses cannot simply be interpreted as sensory responses to the retinal slip input; they may in fact be deeply associated with the motor control command of the eye movement which would be elicited by the retinal slip.