(A) Examples of action potential trains in WT (upper trace) and Df(16)A+/− neurons (lower trace) in response to a 500 msec depolarizing 0.4 nA current step from −65mV. (B)
Df(16)A+/− neurons fired fewer action potentials in response to large current injections for 500 msec (p < 0.05 at ≥ 400 pA) when resting membrane potential was adjusted to −65 mV (2-way repeated measures ANOVA, genotype: p = 0.068, genotype x current: p < 0.001, WT: n = 8, Df(16)A+/−: n = 8). (C) Examples of voltage sags in WT and Df(16)A+/− neurons in response to a 75 pA hyperpolarizing current step. (D) Accommodation of spike rates was seen in both genotypes but it was greater in Df(16)A+/− neurons (2-way repeated measures ANOVA, genotype: p = 0.05, genotype x spike number: p = 0.002: n = 8, Df(16)A+/−: n = 7, 1 cell < 16 APs). (E) Action potential trains evoked from resting potential did not differ between genotypes (2-way repeated measures ANOVA, genotype: p = 0.49, genotype x current: p = 0.73, WT: n = 15, Df(16)A+/−: n = 13).