To obtain estimates of localized power of the generally non-stationary evoked potential time series, we used a recently developed time-frequency representation (TFR) method, the S-transform (Stockwell and others 1996). Details of the method for computation of the estimate of localized power were published previously (Jones and others 2004). The electrophysiological phenotypes used in the analysis were derived using single trial visual oddball event related data from the target experimental conditions. The instantaneous amplitudes of the S-transform TFR were averaged across single trials, per individual, to obtain an estimate of event related total amplitude response (stimulus onset phase locked plus non-phase locked oscillations). The total amplitude response enhances events that occur in a similar time range as related to the stimulus onset, and irrespective of their phase relations. Mean values were calculated from the TFR for use as phenotypes within time-frequency regions of interest (TFROI’s) specified by frequency band ranges and time intervals (Lachaux and others 2003). This study focused on the evoked oscillation TFROI corresponding to the lower theta (4–5 Hz) frequency band and the 300–500 ms time window range,
