Normalized current threshold for action potential (AP) train atΔfacross the range of stimulation frequencies. Thresholds were normalized to threshold of a stimulation with 10 Hz sine wave (horizontal red dashed line).*comparisons survived Bonferroni correction (p-value = 0.0071);**p< 0.005 and***p< 0.0005; repeated-measures ANOVA, post hoc paired t test. Boxplots: central mark, median; box edges, 25th and 75th percentiles; whiskers, extend up to 1.5 × interquartile range box edges; +, datapoints outside this range.n= 22 (10 Hz), 22 (50 Hz), 21 (100 Hz), 21 (500 Hz), 20 (1,000 Hz), 20 (2,500 Hz), and 19 (5,000 Hz) cells.
