Modern neuroscience reveals that altered states arise from intricate shifts in brain networks, neurochemistry, and electrical rhythms—transforming perception, emotion, and self-awareness.
The Default Mode Network acts as the brain’s “self-system,” responsible for self-referential thinking, autobiographical memory, and our continuous sense of identity. During ASCs, the DMN’s activity changes markedly:
Psychedelics tend to decrease connectivity within the DMN, producing experiences of ego-dissolution and expanded awareness.
Meditation and flow states modulate communication between the DMN and executive networks, promoting focused attention and reduced internal chatter.
These changes suggest that altering DMN dynamics can temporarily loosen rigid self-models, opening access to new modes of consciousness and creativity.
The Entropic Brain Hypothesis describes consciousness as existing along a spectrum of entropy—a measure of the brain’s informational richness and flexibility.
High-entropy states (psychedelics, REM sleep, early psychosis) are fluid, expansive, and unconstrained.
Low-entropy states (ordinary waking consciousness, depression, anesthesia) are more structured but rigid.
Clinically, psychedelics may increase neural entropy, disrupting maladaptive thought patterns and restoring cognitive flexibility—an effect linked to improved mental health outcomes.
This model explains the temporary downregulation of the prefrontal cortex—the brain region associated with planning, self-monitoring, and time awareness—during certain altered states. When this region quiets down, individuals often experience:
A loss of self-consciousness
Distorted sense of time
Effortless performance and absorption
This mechanism underlies flow, deep meditation, and creative improvisation, highlighting how less control can sometimes unlock more presence.
The REBUS model proposes that psychedelics soften the brain’s rigid predictive models, allowing new sensory information to update deeply ingrained beliefs. This relaxed state of top-down control enhances:
Learning and cognitive flexibility
Emotional release and insight
Integration of new adaptive patterns
In essence, REBUS describes how psychedelics facilitate a “reset” of the mind’s predictive architecture, enabling transformative psychological change.
Emerging evidence suggests that psychedelics and certain ASCs can reopen windows of heightened neuroplasticity, similar to those seen during early brain development. These temporary “critical periods” allow for:
Accelerated neural rewiring
Enhanced emotional learning
Increased capacity for behavioral change
This mechanism may explain why profound experiences—when properly integrated—can lead to lasting therapeutic and developmental outcomes.1-4
Carhart-Harris, R. L.; Leech, R.; Hellyer, P. J.; Shanahan, M.; Feilding, A.; Tagliazucchi, E.; Chialvo, D. R.; Nutt, D. The entropic brain: a theory of conscious states informed by neuroimaging research with psychedelic drugs. Front. Hum. Neurosci. 2014, 8, 20. DOI: 10.3389/fnhum.2014.00020 From NLM PubMed-not-MEDLINE.
Herzog, R.; Mediano, P. A. M.; Rosas, F. E.; Lodder, P.; Carhart-Harris, R.; Perl, Y. S.; Tagliazucchi, E.; Cofre, R. A whole-brain model of the neural entropy increase elicited by psychedelic drugs. Sci. Rep. 2023, 13 (1), 6244. DOI: 10.1038/s41598-023-32649-7 From NLM Medline.
Carhart-Harris, R. L.; Goodwin, G. M. The Therapeutic Potential of Psychedelic Drugs: Past, Present, and Future. Neuropsychopharmacology 2017, 42 (11), 2105-2113. DOI: 10.1038/npp.2017.84 From NLM Medline.
Greco, A.; Gallitto, G.; D'Alessandro, M.; Rastelli, C. Increased Entropic Brain Dynamics during DeepDream-Induced Altered Perceptual Phenomenology. Entropy (Basel) 2021, 23 (7). DOI: 10.3390/e23070839 From NLM PubMed-not-MEDLINE.
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