Fig. 1

Grand mean waveforms for control (top) and patient (bottom) groups for electrode sites over fronto-central scalp. The control group shows typical auditory evoked potentials (AEPs), whereas in the Rett group, there is a substantially broader initial cortical response to both the standard and the deviant (the P1; blue and red traces, respectively), and dramatic attenuation of the N1-P2 complex that is particularly pronounced for the standard. Nevertheless, in the Rett group as in the control group, the oddball stimulus elicited a larger AEP in the N1-P2 timeframe. This is consistent with the MMN response (see purple trace for standard minus oddball difference wave) and suggests that automatic change detection occurred. Notably, the MMN appears delayed and of longer duration in the Rett group. Red and blue opaque shading around the waveform plots reflect standard errors