STATE-DEPENDENCE OF CLIMBING FIBER-DRIVEN CALCIUM TRANSIENTS IN PURKINJE CELLS

The recently described bi-stability of Purkinje cells and the state-dependence of the complex spike waveform suggest that calcium currents may play a pivotal role in both the complex spike waveform and the state of the membrane voltage. Here we used Ca2+ imaging to record the changes in intracellular [Ca2+] that are elicited by either spontaneous or climbing fiber-evoked activity in rat Purkinje cells. We show that a continuous somatic Ca2+ influx occurs during an UP state. Furthermore Ca2+ transients that are evoked by climbing fiber stimulation are state-dependent. Somatic transients are smaller following an UP state, while dendritic transients are smaller following a DOWN state. The state-dependence of these signals should affect the intrinsic firing of Purkinje cells as well as plastic processes that modulate synaptic strength. (C) 2009 IBRO. Published by Elsevier Ltd. All rights reserved.