Climbing fiber responses of cerebellar Purkinje cells to passive movement of the cat forepaw.

The activity of cerebellar Purkinje cells during controlled and passive movement of the forepaw was studied in the cat. Burst responses characteristic of activation by climbing fibers were observed in Purkinje cells in lobules Vb and Vc of the cerebellar vermis and paravermis. The climbing fiber responses followed the onset of a movement with a latency ranging from 20 to 60 msec depending upon movement type and amplitude. Responsive Purkinje cells were localized in a well defined parasagittal strip very near the paravermal vein in lobules Vb and Vc. Cells within the responsive strip responded with identical response probabilities and latencies for any particular type of movement presentation. Responses were independent of starting paw position and direction of movement. Climbing fiber responses could be evoked by extremely small movements with most cells responding to displacements of 50 mum. The latencies and probabilities for climbing fiber responses were inversely related to movement amplitude with latencies as long as 80 msec for very small displacements.