File:FMRI Static Resting-State Functional Connectivity effects of DMT.jpg

English: "Reduced RSN integrity and segregation and increased GFC with DMT. (A) Analysis of within-network sRSFC or integrity (parameter estimates and Fisher Z values) for DMT (red) versus placebo (blue) shows significant reductions in integrity for 5 of 7 networks, and increases in global functional connectivity (GFC) in 3 of 7 networks (FDR correction, P < 0.05). (B) Decreased between-network segregation was especially pronounced for the FP/DMN/SAL or TOP networks and other networks (*P < 0.05, FDR corrected). (C) Increases in GFC were especially pronounced for regions associated with the TOP of the human brain’s principal gradient (P < 0.05, FDR corrected). See SI Appendix, Figs. S2 and S3 for complementary analysis without motion confounds and SI Appendix, Fig. S5 for analysis using global signal regression. (D) Networks used for analyses (sRSFC = static resting-state functional connectivity; networks; VIS = visual; SM = somatomotor; DAN = dorsal attentional; SAL = ventral attentional/salience; LIM = limbic; FP = frontoparietal; DMN = default mode; TOP = transmodal association pole)." "Twenty participants (mean age = 33.5 y, SD = 7.9, 7 females) were given a high dose (20 mg) of DMT fumarate and placebo in a within-subjects, counterbalanced, pseudo-randomized design. Simultaneous fMRI and EEG recordings took place from 8 min before until 20 min after the DMT/placebo injection (see SI Appendix, Fig. S1 for subjective effects). To determine the effects of DMT on brain connectivity, using the fMRI BOLD signal, we analyzed resting state functional connectivity (RSFC) averaged over an 8-min period after the injection of DMT/placebo, coinciding with the time of peak subjective intensity. To differentiate this time-averaged analytical approach from more dynamic metrics, we name it “static” RSFC or “sRSFC.” For within-network RSFC or integrity and between-network RSFC or segregation, we used independent component analysis (ICA) to derive a set of canonical resting-state networks (RSNs), followed by the “dual regression” approach to examine RSFC changes (35). To complement these analyses, we computed global functional connectivity (GFC), which indexes the average RSFC (i.e., correlation) for a given region with all other regions in the brain (see Materials and Methods for details). Compared with placebo, DMT significantly decreased the within-network integrity of all canonical RSNs (P < 0.05, FDR corrected), with the exception of the salience (SAL) and limbic (LIM) networks. Significant increases in GFC were found in the SAL, frontoparietal (FP), and default-mode networks (DMN; P < 0.05, FDR corrected) (Fig. 1A), overlapping the transmodal association cortex pole (or TOP) of the human brain’s principal RSFC gradient (36). Additionally, DMT was found to decrease between-network segregation, especially for frontoparietal, salience, and default-mode networks (Fig. 1B) (P < 0.05, FDR corrected), again implicating the transmodal pole."