Functional changes in brain activity in altered states of consciousness : An SDM-PSI comparative systematic review and meta-analysis

Abstract

Altered states of consciousness (ASCs) induced by psychological practices (mindfulness meditation, hypnosis, self-induced trance) and pharmacological agents (classical and atypical psychedelics) are increasingly linked to therapeutic change, yet their shared and unique neural signatures remain uncertain. We conducted three preregistered, coordinate-based meta-analyses using SDM-PSI, mindfulness meditation (k = 9), hypnosis (k = 7), and psychedelics (k = 25; ketamine, MDMA, LSD, psilocybin, ayahuasca, DMT), with a total subject number N = 961, and a narrative review of trance (k = 1). Two aims guided the study: (1) map whole-brain functional alterations for each ASC; (2) examine exploratory cross-state convergence via descriptive overlap of threshold maps. All three analyses showed low heterogeneity and no evidence of small-study bias; however, k < 10 for meditation and hypnosis renders bias tests under-powered. TFCE-corrected effects were observed only for meditation; findings for hypnosis and psychedelics remained uncorrected and exploratory. At exploratory significance, all ASC categories showed decreased activity in default-mode hubs (posterior cingulate, medial prefrontal) with greater engagement of salience and executive regions (anterior cingulate, insula, dorsolateral prefrontal); psychedelics additionally involved visual and thalamic circuits, whereas hypnosis preferentially modulated sensorimotor-integration zones. These results suggest candidate region-level commonalities alongside modality-specific features. They provide a transparent scaffold for confirmatory work: preregistered, correction-controlled cross-state conjunctions; modality-homogeneous and substance-specific analyses (classical vs atypical); and quality-weighted sensitivity checks, potentially bridging neurophenomenology with clinical applications in mental health.

In the evidence

This study is part of the evidence base for 2 syntheses in the library. Here is how each one recorded it.

• State of the evidence: Altered states of consciousness ↕Mixed

  At exploratory significance, all altered-state categories showed decreased default-mode hub activity with greater salience and executive engagement; only meditation effects survived correction, and psychedelics additionally involved visual and thalamic circuits.

  Synthesized October 19, 2026

• State of the evidence: Meditation ↕Mixed

  TFCE-corrected effects were observed only for meditation, with decreased default-mode hub activity and greater salience/executive engagement; hypnosis and psychedelic findings remained uncorrected and exploratory.

  Synthesized October 19, 2026

Comparable studies

Other systematic reviews and meta-analyses on altered states of consciousness, most cited first.