Effective connectivity of functionally anticorrelated networks under LSD
Research is examining how brain function is altered under the influence of LSD. A recent small, double-blind placebo-controlled study (n=25) assessed whether a change in anticorrelated networks (default mode network (DMN)/salience network (SN)) underlies the peak effects of LSD (100μg) using fMRI. The human brain is intrinsically organised into dynamic, anticorrelated functional networks.
Inhibitory effective connectivity from the SN to DMN became excitatory, and inhibitory effective connectivity from DMN to DAN decreased under the peak effect of LSD suggesting that diminution of the functional anticorrelation between resting state networks that may be a key neural mechanism of LSD and underlie ego dissolution.
Abstract
“Background Classic psychedelic-induced ego dissolution involves a shift in the sense of self and blurring of boundary between the self and the world. A similar phenomenon is identified in psychopathology and is associated to 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.
Methods To test whether change in anticorrelated networks underlie the peak effects of LSD, we applied dynamic causal modeling to infer effective connectivity of resting state functional MRI scans from a study of 25 healthy adults who were administered 100μg of LSD, or placebo.
Results We found that inhibitory effective connectivity from the SN to DMN became excitatory, and inhibitory effective connectivity from DMN to DAN decreased under the peak effect of LSD.
Conclusions The effective connectivity changes we identify may reflect diminution of the functional anticorrelation between resting state networks that may be a key neural mechanism of LSD and underlie ego dissolution. Our findings suggest changes to sense of self and subject-object boundaries across different states of consciousness may depend upon the organised balance of effective connectivity of resting state networks.”
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