Fig. 3.

a The strength-duration time constant reflects nodal persistent Na⁺ channel conductances and was significantly increased in patients with amyotrophic lateral sclerosis (ALS; filled circles) compared to controls (clear squares). b Mean SDTC was significantly increased in both familial ALS and sporadic ALS compared with controls (*p < 0.05; **p < 0.01). c Recovery cycle waveforms in patients with motor neuron disease (MND; filled circles) compared with controls (clear squares) demonstrating increased superexcitability in patients with ALS. d Threshold electrotonus waveforms in patients with ALS (filled circles) compared with controls (clear squares) demonstrating increased threshold change in threshold electrotonus depolarizing direction (TEd) 90–100 ms in patients with ALS