A–C, electroresponsiveness of cerebellar granule cells of WT and KV10.1 KO mice. A, representative traces recorded in granule cells from WT (left) and KV10.1 KO mice (right) in response to injection of square current pulses (bottom). Both genotypes showed inward rectification of the membrane potential during hyperpolarizing pulses and regular spiking after reaching a threshold potential. B, average membrane potential recorded in whole-cell current clamp mode in response to injection of square current pulses (2 s) in the presence of TTX. C, average firing frequency of WT and KV10.1 KO cells upon injection of 2 s square current pulses ranging between −35 and +35 pA in 5 pA increments. D–F, AP properties are not altered in KV10.1 KO mice. D, undershoot amplitudes measured from threshold (a), AP amplitude (b), half-width (c) and 10–90% rise time (d) are compared. Filled bars, WT, n = 11 cells; grey bars, KV10.1 KO, n = 8 cells. E, representative APs recorded in a WT (left) and KV10.1 KO (right) granule cell. F, maximum rate of rise of the AP plotted against the maximum rate of fall as determined by analysing the first differential. Filled circles, WT; open circles, KV10.1 KO. The data points were fitted with straight lines, which were not significantly different between genotypes. The dashed line represents unity.