A. Schematic of the electrophysiological recording configuration and synaptic inputs onto cerebellar PCs. B. Electrical stimulation of climbing fibers (CF, top) and granule cell-mediated parallel fiber (PF, bottom). Whole cell mode voltage-clamp recordings showed no difference in the conductance (g) of single fiber CF inputs (control (con) n=20 cells, 5 mice; mutant (mut) n=16 cells, 5 mice, p=0.34), or the paired-pulse ratio (PPR) of either CF or PF inputs (CF PPR: con n=8, mut n=5, p=0.51). C. Electrical stimulation revealed no differences in the ratio of evoked synaptic excitation to inhibition (E/I ratio; con n=29, mut n=17, p=0.19). D. Extracelluar recording of spontaneous PC spiking (left) revealed a significantly lower spike rate in hets and mutants (right, con n=77 cells, 12 mice, het n=62 cells, 7 mice; n=42 cells, 9 mice). E. Whole cell mode current-clamp recordings showed reduced excitability in PCs from hets and mutants compared to control PCs. Left, current injections of 1 and 3 nA produced fewer spikes in PCs from hets and mutants. Right, average data showed a reduced spike output for mutant PCs (con n=77 cells, 12 mice, het n=48 cells, 7 mice; n=43 cells, 9 mice). ns, p>0.05, * p<0.05, ** p<0.01. two-way ANOVA, Bonferroni's post hoc analysis.