Figure 3: Representative traces of action potential trains and input-output relationships: (adapted from Reference [12] with modifications). (A) The 500- ms current injection period is indicated below. The traces presented are those evoked by a 100-pA current injection. Toward the end of the current injection, D1-1 neurons showed more prominent attenuation of action potential amplitude compared to 201B7 neurons, as indicated by the dotted arrows. The frequency of action potentials was also lower in D1-1. Scale bars indicate 20 mV and 100 ms. (B) Mean of the total number of action potentials evoked during the 500-ms stimulation period vs. injection current intensity (input–out put relationship). In all cell lines, the number of action potentials increased with intensifying currents. However, when current intensities exceeded 60 pA, the rate of action potential increase plateaued in both patient lines, which was not the case in control cells.