Figure 1.

Raw event-related spectrum (absolute log-ERS) on the left versus baseline corrected ERSP (log-ERSP) on the right for scalp EEG data trials. Electrode Iz from the “animal” dataset of subject “CLM” (see Materials and Methods) was used to compute FFT-based ERS and ERSP. ERS was computed using Eq. 1and log-ERSP was computed using the classical baseline correction divisive method described in Eq. 6(see Materials and Methods). Although post-stimulus power decrease at about 7 Hz is clearly visible on the ERSP image, it is more difficult to see in the ERS image where large low-frequency changes stretch the color scale limits. This shows the usefulness of removing the pre-stimulus baseline for scalp EEG data.