Figure 5
Changes in the magnitude of whole-brain fALFF following ketamine administration. (a) Time-varying PR and fALFF (normalized by the initial value at a given session) exhibited a separation between ketamine (green cluster) and saline (gray cluster) sessions (note the ketamine cluster in the bottom right corner indicating an increase in the PR and decrease in fALFF). (b) By using a linear regression model with time-varying PR and fALFF (both HbO and HbR) as input features, we were able to predict the total RMEQ score. Shown are the model predictions on the validation set during each fold (mean ± SEM of the time-varying predictions within each session versus the reported RMEQ total score for the entire session). (c) We evaluated the trained model on the time-varying features to obtain time-varying RMEQ score predictions (on the validation set). Shown are the normalized prediction scores sorted by the peak time across participants. It appears that different participants may reach their peak of mystical experiences at different time points after ketamine administration. (d) GEE model revealed that the interaction term between session type (ketamine vs. saline) and whole-brain fALFF (whether it was high or low throughout the session) was a significant factor in the change in QIDS scores (HbO: p = 3.53 × 10−6, HbR: p = 4.76 × 10−7). Shown are the change in QIDS scores after the ketamine sessions when we performed a median split on the participants’ fALFF during their ketamine session.
