Interaction between responses in Purkinje cells evoked by climbing fibre impulses and parallel fibre volleys in the cat.

Abstract

The plateau-like depolarizing potentials evoked in Purkinje cell dendrites by impulses in climbing fibers were conditioned by single parallel fiber volleys and investigated by intra- and extracellular recording from cat cerebellar cortex. The conditioning parallel fiber volleys evoked predominantly inhibitory potentials of long duration in the Purkinje cell dendrites. Massive parallel fiber volleys, which may evoke plateau-like depolarizing potentials, were avoided. In proximal dendrites parallel fiber volleys preceding climbing fiber responses reduced or abolished the plateau potential, whereas the initial spike-like component of the climbing fiber responses was largely unaffected. Parallel fiber stimulation during already established plateau potentials immediately terminated the plateaus. In distal dendrites parallel fiber stimulation preceding climbing fiber responses reduced or abolished both the plateau potential and the initial component of the climbing fiber responses. Parallel fiber stimulation during established plateau potentials did not immediately terminate the plateau potentials but reduced their duration. Single dendritic branches of Purkinje cells serve as independent integrators of mossy fiber and climbing fiber inputs.