DMT alters cortical travelling waves

Abstract

Psychedelic drugs are potent modulators of conscious states and therefore powerful tools for investigating their neurobiology. N,N, Dimethyltryptamine (DMT) can rapidly induce an extremely immersive state of consciousness characterized by vivid and elaborate visual imagery. Here, we investigated the electrophysiological correlates of the DMT induced altered state from a pool of participants receiving DMT and (separately) placebo (saline) while instructed to keep their eyes closed. Consistent with our hypotheses, results revealed a spatio-temporal pattern of cortical activation (i.e., travelling waves) similar to that elicited by visual stimulation. Moreover, the typical top-down alpha-band rhythms of closed-eyes rest were significantly decreased, while the bottom-up forward wave was significantly increased. These results support a recent model proposing that psychedelics reduce the 'precision-weighting of priors', thus altering the balance of top-down versus bottom-up information passing. The robust hypothesis-confirming nature of these findings imply the discovery of an important mechanistic principle underpinning psychedelic-induced altered states.

Prefrontal contributions to the stability and variability of thought and conscious experience

“…This can also be described as a decrease in top-down and an increase in bottom-up information flow (Fig. 4), consistent with experimental findings of psychedelically-induced reductions to brainwide top-down signaling [73], directed information flow [60,74], and hierarchical information flow [29,30]. Such alterations to hierarchical information flow may play a role in creating the increased variability or diversity of brain activity that is observed during psychedelic states [75][76][77][78][79][80], given that bottom-up information flow is no longer as constrained by top-down sources.…”

“…In particular, the field of psychedelics research could benefit from a more specific discrimination between different brain networks and regions. Neuroscientific work on psychedelics often makes use of whole-brain measurements [29,30,61,73,75,77,99,339]. These approaches have and will continue to be highly beneficial for understanding the effects of psychedelics on global brain measures, but may obscure the more specialized contributions made by specific brain regions and networks to psychological phenomena.…”

Does Psychedelic Therapy Have a Transdiagnostic Action and Prophylactic Potential?

“…In the context of psychedelic therapy, their occurrence strongly predicts positive long-term clinical outcomes (69, 182). The opening-up of a new perspective may be a common consequence of an acute entropic brain effect (185)-and recent evidence of increased bottom-up information flow under psychedelics hints at relevant mechanisms by which insight may occur, namely, reduced top-down and increased bottom-up information flow (240).…”

Transcriptomics-informed large-scale cortical model captures topography of pharmacological neuroimaging effects of LSD

“…Spatial gradients in drug targets, such as serotonergic receptor subtypes, can be approximated using the topography of gene transcripts – particularly in the case of receptors for which the field lacks suitable PET radioligands. Studies that leverage transcriptomic mapping ( Grandjean et al, 2021 ) and regionally heterogeneous modeling ( Demirtaş et al, 2019 ) will further elucidate the mechanisms underlying the complex functional signatures of pharmacologically induced neuromodulatory effects ( Pfeffer et al, 2020 ; Alamia et al, 2020 ).…”