a, Statistical comparison of spike delay as function of pre-polarization membrane potential. To confirm that late spiking property of Reg-BFCNs was not due to different testing conditions, we compared pre-polarization membrane potentials between groups (n = 31 late-firing and n = 29 early firing cholinergic cells, two-sample, two-sided Kolmogorov-Smirnov test). Bars show median. b, Example traces of a Reg-BFCN (left) and Burst-BFCN (right) spike response at hyperpolarized and depolarized membrane potentials. Note that the late-firing property of Reg-BFCNs is characteristic to hyperpolarized membrane potentials. c, Minimum spike delay of each recorded cell vs. burst index (green, Reg-BFCNs; red, Burst-BFCNs). d, Minimum spike delay group statistics (n = 31 late-firing and n = 29 early firing cholinergic cells). Box-whisker plots show median, interquartile range, non-outlier range and outliers.