Altered stated of consciousness
These are scientifically measurable shifts in perception, emotion, and self-awareness
Introduction
Altered States of Consciousness (ASCs) are transient, reversible, and multidimensional shifts in perception, emotion, cognition, and self-awareness—subjectively recognized by the individual as distinctly different from ordinary waking consciousness. Documented across human history since the Paleolithic era, ASCs can be natural or endogenous (e.g., sleep, deep creative focus, exercise), pharmacologically induced (e.g., general anesthesia, psychoactive substances), induced by other means (e.g., meditation, hypnosis, music, sensory deprivation), and pathological (e.g., epilepsy, disorders of consciousness). Far from being anomalies, they are natural expressions of the brain’s adaptive capacity, marked by measurable changes in neurotransmitter activity (serotonin, dopamine, endorphins), hormonal balance (notably cortisol), and autonomic nervous system regulation between sympathetic and parasympathetic states. Each ASC carries a unique phenomenological fingerprint—a pattern of brain-body coherence revealing how consciousness can reorganize itself to heal, learn, and evolve1-3
The Neuroscience Behind Altered States
Altered states of consciousness can be understood through several key neurophysiological models that reveal how the brain reorganizes itself when consciousness shifts.
The Cortico-Striato-Thalamo-Cortical (CSTC) model explains how disruptions in the brain’s sensory “filter”—the thalamus—can flood the cortex with unfiltered information, leading to experiences like expanded perception or ego-dissolution.
The Hierarchical Alteration model shows how changes at basic neurochemical levels can ripple upward through the brain’s networks, reshaping higher functions such as self-control and awareness.
The Entropic Brain Hypothesis (EBH) describes ASCs as states of altered “entropy” or brain order: psychedelics increase entropy and open cognition, while low-entropy states narrow it.
Finally, Predictive Coding models (including the REBUS framework) suggest that psychedelics and other ASCs relax the brain’s rigid beliefs, allowing raw sensory data to flow freely and reshape perception.
Together, these models bridge subjective experience with neural dynamics, showing that altered states are not chaos—but sophisticated reorganizations of consciousness revealing the brain’s extraordinary flexibility and adaptive intelligence.
References
Fort, L. D.; Costines, C.; Wittmann, M.; Demertzi, A.; Schmidt, T. T. Classification schemes of altered states of consciousness. Neurosci Biobehav Rev 2025, 175, 106178. DOI: 10.1016/j.neubiorev.2025.106178 From NLM Medline.
Cofre, R.; Herzog, R.; Mediano, P. A. M.; Piccinini, J.; Rosas, F. E.; Sanz Perl, Y.; Tagliazucchi, E. Whole-Brain Models to Explore Altered States of Consciousness from the Bottom Up. Brain Sci 2020, 10 (9). DOI: 10.3390/brainsci10090626 From NLM PubMed-not-MEDLINE.
Vaitl, D.; Birbaumer, N.; Gruzelier, J.; Jamieson, G. A.; Kotchoubey, B.; Kubler, A.; Lehmann, D.; Miltner, W. H.; Ott, U.; Putz, P.; et al. Psychobiology of altered states of consciousness. Psychol. Bull. 2005, 131 (1), 98-127. DOI: 10.1037/0033-2909.131.1.98 From NLM Medline.
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