Freudian constructs may have neurobiological substrates. Descriptions of primary and secondary processes align with self-organized activity in hierarchical cortical systems, and descriptions of the ego align with functions of the default-mode network and its exchanges with subordinate brain systems. This account views the brain as a hierarchical inference machine that minimizes free-energy, a process formally similar to Freudian energy treatments. The synthesis is substantiated by showing that descriptions of the primary process are consistent with the phenomenology and neurophysiology of rapid eye movement sleep, early acute psychotic states, temporal lobe epilepsy auras, and hallucinogenic drug states.
Users of hallucinogenic drugs report less harm from classic hallucinogens like LSD and psilocybin compared to MDMA, cannabis, ketamine, and alcohol. Over 600 web-based survey responses indicated benefits including help with mood disorders, addictions, and migraines, along with long-term wellbeing improvements. Symptoms of hallucinogen persisting perceptual disorder were most associated with LSD, though few users found them troubling. Eighty-one percent reported a spiritual experience on a hallucinogen, and over 90% considered access to the unconscious mind a specific property of classic hallucinogens. These findings cautiously support calls for systematic investigation of the therapeutic potential of classic hallucinogens.