The averaged induced TF representation for each group at electrode FCz for the target stimulus is shown in Figure 2. These TF representations, also filtered in the theta band to accentuate the relevant activity, show an ERS of theta activity occurring between about 200 and 600 msec. Based on visual inspection of the grand-averaged induced TF surfaces, a theta poststimulus TFROI was selected that spanned a time range of 250–475 msec and a frequency range of 3–6 Hz (indicated by a box overlaid on the induced TF surfaces). The corresponding prestimulus reference TFROI (also identified by a box on the TF surface) had the same frequency range, with a time range of −200 to −95 msec. Figure 2 also shows topographic maps for the mean activity within the poststimulus TFROI for each group. ITC values for statistical analyses were obtained by averaging ITC within the same poststimulus TFROI as the induced theta.
