FMAER and corresponding FFT, before and after steroids in regressive autism. 4 Hz FMAER waveform data are shown within schematic ovals in vertex view with nose up, and left side of scalp to image left. The corresponding power spectra are shown to the immediate right. The top waveform and FFT displays were obtained prior to steroid administration. The bottom, corresponding displays were obtained after steroid administration. The vertical arrow to the lower left of each image represents 10 μV and the horizontal arrow beneath represents one second waveform length. The labels adjacent to the FMAER waveforms correspond to the standard EEG electrode 10–10 naming convention. Twenty-four electrodes’ waveforms are shown. The FFT power spectral data horizontal axis covers the 0–30 Hz range. Note the near absent 4 Hz FMAER waveform response before and excellent 4 Hz waveform response after steroid administration. Note the spread of spectral power over many frequencies in the FFT display before (above) which represents a distorted response. This contrasts to the nearly perfect 4 Hz response after steroid treatment (below) which shows little spectral spread (little distortion). For the vertex view display, waveforms are shown overlying their standard ‘10-10’ locations. For the FFT graphs, channel order from top to bottom is: F3, F4, C3, C4, P3, P4, O1, O2, Fp1, Fp2, F7, F8, T7, T8, P7, P8, FT9, FT10, TP9, TP10, Fz, Cz, Pz, Oz. The common average reference is utilized for the displayed data (a reference free or ‘rfr’ technique) . Abbreviations: A = anterior, P = posterior, L-left, R = right, FMAER = 4 Hz frequency modulated auditory evoked response, FFT = fast Fourier transform - power spectrum analysis shown as μV2/Hz, μV = microvolt, Hz = Hertz or cycles per second.