LR neurons compared with controls, P = 0.02) and a faster kinetics gave rise to a bigger amplitude spike. If we look at the area under the curve of the sodium currents from −60 to −20 mV, it is increased by 19%, similar to the increase in spike height. The 5-ms AHP amplitude was larger in LR neurons (+21%, P = 0.03) than in control neurons and was even larger in NR neurons (+49% P = 0.0003) (Figure 3i). Spike width was the narrowest in LR and widest in NR neurons, with a significant difference between NR and LR neurons (+21%, P = 0.03) (Figure 3j). The threshold for firing was 6 mV higher (more depolarized) in NR neurons compared with the other two groups (P<0.0001 NR to control, P<0.0001 NR to LR) (Figure 3k). We found that the distinct features of LR and NR neurons vs control neurons that were evident at 3.5 weeks differentiation were observed through the entire measurement period of 10– 45 days postdifferentiation, and the significance of the results increased in all measured parameters (except for spike width) when analyzing the entire data set. Remarkably, while the endophenotype of hyperexcitability is shared between NR and
