DMT-induced shifts in criticality correlate with self-dissolution

abstract

Psychedelics profoundly alter subjective experience and brain dynamics. Brain oscillations express signatures of near-critical dynamics relevant to healthy function. Variation in proximity to criticality has been suggested to underlie the experiential and neurological effects of psychedelics. Here, we investigate the effects of psychedelic substances (DMTs) with respect to the severity and subjective experience of brain oscillations in humans of either sex. We found that DMT severely attenuates the dynamics of brain oscillations in alpha and adjacent frequency bands. In this context, entropy increases while complexity decreases. We find that significant changes observed in the alpha and theta bands are correlated with intensity ratings of self-disintegration, a hallmark of the psychedelic experience. Finally, using a recently developed metric, the functional excitatory-inhibitory ratio, we find that the severity of DMT-induced shifts in brain oscillations is toward sub-critical regimes. These findings have major implications for the understanding of psychedelic mechanisms of action in the human brain and the neurological basis of altered states of consciousness.

importance statement Criticality is characterized by fluctuations occurring over a wide range of spatiotemporal scales and at high complexity. Here, we examine the effects of DMT, a classic psychedelic, with respect to the severity and subjective experience of brain oscillations. We find that DMT shifts the normally dominant alpha oscillations toward a quiescent subcritical state, increasing entropy while reducing complexity, and this shift correlates with the intensity of the disruption of the sense of self.