Effective Connectivity of LSD-induced Ego Dissolution

Classic psychedelic-induced ego dissolution involves a shift in the sense of self and blurring of the boundary between the self and the world. A similar phenomenon is identified in psychopathology and is associated with the balance of anticorrelated activity between the default mode network (DMN), which directs attention inwards, and the salience network (SN), which recruits the dorsal attention network (DAN) to direct attention outward. To test whether a change in anticorrelated networks underlies the peak effects of LSD, we applied dynamic causal modelling to infer (directed) effective connectivity of resting-state functional MRI scans from a double-blind, randomised, placebo-controlled cross-over study where 100mg of LSD, or placebo, was administered to 25 healthy adults. Under the peak effects of LSD, the hierarchical organisation of the resting-state brain networks was altered. Inhibitory effective connectivity from the SN to DMN decreased and became excitatory, and inhibitory effective connectivity from DMN to DAN decreased when compared to the placebo. These changes in connectivity reflect diminution of the anticorrelation between the resting state networks which may be a key neural mechanism of LSD-induced ego dissolution. Our findings suggest the hierarchically organised balance of resting-state networks is a central feature in the construct of self.