Fig. 2.
Dynamics of the EEG spectrogram during induction and emergence from propofol-induced unconsciousness. (A) Group-level click (blue, Pclicks) and verbal (red, Pverbal) response-probability curves, as shown previously in Fig. 1D. (B) Group-level baseline-normalized spectrograms from a frontal channel (approximately Fz, nearest-neighbor Laplacian reference) aligned with respect to LOC and ROC. The white contour circumscribes the regions where power differs significantly from baseline (P < 0.05, sign test) and indicates significant increases in power spanning low-frequency (0.1–1Hz) through gamma (25–35 Hz) bands. (C) Group-level time course of power in low-frequency, alpha (8–12 Hz), and gamma bands aligned with respect to LOC and ROC. (D) Group-level spatial distribution of low-frequency, alpha, and gamma power during unconsciousness (LOC + 15 min). These analyses show that changes in broad-band gamma/beta power coincide with the behavioral changes before LOC and after ROC, whereas changes in slow and alpha power coincide with LOC and ROC.