A, fraction of cells generating at least one AP and (B) the mean number of AP produced in response to a series of 6 incremental 500 ms depolarizing current injections (10–60 pA) from a set pre‐stimulus potential of −80 mV. C, instantaneous AP frequency vs. interval number for a 10, 30 and 60 pA, 500 ms current stimuli. D, instantaneous AP frequency vs. interval number and inset a sample voltage response, for a 30 and 60 pA, 2.5 s current stimuli. All error bars represent the SEM. All cells were set at −80 mV prior to current application.