Abnormal topographic features and decreased activations of CSD have been reported in schizophrenic subjects in specific ERP components and in time-frequency measures under various task conditions (See Table 1, section 2). Significantly reduced CSD activations of P3 component over the central and parietal regions of the auditory oddball paradigm have been reported in schizophrenic patients during baseline (Time 1) (Turetsky et al., 1998a) and follow up (Time 2) recordings (Turetsky et al., 1998b) , although there were no significant CSD differences between Time 1 and Time 2. Further, CSD transformation enabled to identify five spatially distinct subcomponents of the P300 (mean integrated amplitude between 280 and 400 ms poststimulus): bilateral parietal (P3pL and P3pR), bilateral temporal (P3tL and P3tR), and midline frontal (P3f) (Turetsky et al., 1998a, b). These studies pioneered the application of the spatial CSD-PCA method; this also enabled comparison of the amplitudes of hemisphere-related components in two or more groups (Spencer et al., 1999, 2001; Tenke et al., 2008). Extending the study to include unaffected siblings, Turetsky et al. (2000) reported that both schizophrenic patients and unaffected
