{"id":"doi:10.1093/brain/awag206","kind":"review","title":"The entropic brain today","authors":["Carhart-Harris RL"],"author_count":1,"year":2026,"published":"2026-10-01","venue":"Brain : a journal of neurology","cited_by":3,"doi":"10.1093/brain/awag206","arxiv_id":null,"nct_id":null,"source_url":"https://doi.org/10.1093/brain/awag206","archive_url":"https://space-kitty.com/papers/doi:10.1093/brain/awag206","updated":null,"pmid":"42266156","pmcid":"PMC13634631","openalex_id":null,"pdf_url":"https://europepmc.org/articles/PMC13634631/pdf","abstract":"Introduced in 2014 and revised in 2018, the entropic brain hypothesis has accrued a wealth of supportive evidence. The hypothesis states that-along a dimension of 'the size of phenomenal consciousness'-expansive states reliably exhibit increased brain entropy, whereas the inverse applies for states of no or reduced consciousness. Examples of expansive states include expert meditation, flicker-light stimulation, near-death-like experiences, atypical breathing, REM sleep, the pre-ictal aura, unmedicated early psychosis and psychedelic drug states. Examples of states of no or reduced consciousness with low brain entropy, include disorders of consciousness, deep sleep, the anaesthetized state, seizure, post-stroke, ageing, cognitive impairment and neurodegenerative illness. It is shown that the entropic brain has convergent, correlative, predictive, discriminative and external validity. Regarding its predictive validity, increased brain entropy under psilocybin (in a supportive context) predicts subsequent improvements in mental health (improved well-being 1-month post-dose). Regarding its discriminative validity, changes in brain entropy selectively index the 'breadth of subjective experience' versus alternative dimensions, such as arousal. Regarding portability/external validity, an entropy-related function is applied in generative artificial intelligence. In conclusion, the entropic brain is a useful model of conscious states.","abstract_license":"CC-BY (article license as recorded by Europe PMC; abstract reproduced unmodified apart from markup removal)","license":"CC-BY","is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":[],"details":null,"provenance":"europepmc","attribution":"Abstract of \"The entropic brain today\" by Carhart-Harris RL, https://doi.org/10.1093/brain/awag206, used under its Creative Commons Attribution license (CC-BY); markup removed, otherwise unmodified.","topics":[{"slug":"psychiatric-therapeutics","name":"Novel Psychiatric Therapeutics","domain_slug":"neuroscience"}],"cited_in_dossiers":[]}