The entropic brain today

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 breadth of conscious experience— ‘expansive states’ reliably exhibit increased brain entropy whereas the inverse applies for states of no or reduced consciousness. Examples of expansive states include those of expert meditation, flicker light stimulation, the near-death experience, atypical breathing, rapid-eye-movement sleep, the pre-ictal aura, unmedicated early psychosis and psychedelic drug states. Example states of no or reduced consciousness with low brain entropy, include disorders of consciousness, deep sleep, the anesthetized state, seizure, post-stroke, ageing, cognitive impairment, and neurodegenerative disorders. It is shown here that the entropic brain has convergent, correlative, predictive, discriminative and external validity. Regarding its predictive validity, increased brain entropy under psilocybin 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 (temperature) function is used in generative artificial intelligence. In conclusion, the entropic brain is proving to be a useful model of conscious states.