Entropic brain
Explanation
Robin Carhart-Harris, a British neuroscientist who leads research on psychedelics at Imperial College London, proposed in 2014 the entropic brain hypothesis. His thesis: the richness of consciousness correlates with the entropy (disorder, complexity) of brain activity, and profound altered states correspond to significant increases of this entropy with respect to normal waking.
The motivation comes from studies with psychedelics (psilocybin, LSD, DMT) that show a surprising pattern. Subjectively, these states produce very rich, novel experiences, with the dissolution of habitual self and reality structures. Neurally, the brain shows greater entropy: more variability, lower predictability, more fluid communication between regions that normally do not communicate.
Carhart-Harris proposes a classification of conscious states according to their entropy. Low-entropy states (deep sleep, anaesthesia, coma) have little consciousness. Normal waking states have intermediate entropy: enough to be conscious, but structured by habitual categories (self/world, subject/object). High-entropy states (psychedelics, certain meditations, mystical experiences) have richer but less structured consciousness.
This hypothesis connects with Friston's theory on free energy minimization, but in reverse: instead of minimizing surprise, psychedelics "relax priors", allowing sensory information to be processed in non-habitual modes. The brain temporarily abandons its rigid categories and explores a wider space of functional configurations.
Therapeutic implications are notable. In depression and rigid disorders, patients are "trapped" in low-entropy negative cognitive patterns. Psychedelics, by temporarily increasing entropy, allow these patterns to be reorganized, opening therapeutic possibilities that conventional therapies struggle to reach. Recent studies show promising results with psilocybin for treatment-resistant depression.
The entropic brain hypothesis is part of a renaissance of psychedelics research in neuroscience and psychiatry. It connects neuroscience, phenomenology, therapy and philosophy of mind. And it raises deep questions: what does it mean that anomalous states could be "more conscious" in some sense than normal waking? How do we evaluate experiential richness?
Strengths
- Quantifiable framework for levels of consciousness.
- Integrates pharmacology, neuroimaging and phenomenology.
- Basis for therapeutic research with psychedelics.
- Concept of entropy transferable between theories.
Main critiques
- Operational definition of entropy disputed.
- Entropy-phenomenology relation not always clear.
- Theoretical generalizations sometimes excessive.
- Empirical evidence in expansion, not consolidated.