Hemispheric annealing and lateralization under psychedelics (HEALS): A novel hypothesis of psychedelic action in the brain.

A new model called HEALS (Hemispheric Annealing and Lateralization Under Psychedelics) proposes that psychedelics reverse the typical hierarchical relationship between the brain's hemispheres. Normally, the left hemisphere predominates while the right is inhibited. Under psychedelics and other altered states of consciousness, this hierarchy flips, releasing the right hemisphere from left-hemisphere inhibition. The article reviews neuroimaging evidence for lateralization under psychedelics and contrasts cognitive and emotional changes—such as attention, social and emotional intelligence, creativity and insight, and language—with those functions in each hemisphere. It also examines laterality in meditative and trance states, suggesting that many phenomena in psychedelic and other altered states may stem from atypical annealing between hemispheres toward right-hemisphere predominance.

Study at a glance

Abstract

Current models of psychedelic action in the brain propose changes along the dorsal-ventral and anterior-posterior axes but neglect to address the lateral axis. This article proposes a novel model of psychedelic action called HEALS (Hemispheric Annealing and Lateralization Under Psychedelics) which involves the reversal of the typical hierarchical relationship between the two hemispheres of the brain. In typical modes of consciousness, the hemispheres act in parallel process with the left predominating. Under psychedelics, as well as in other altered states of consciousness (ASCs), this hierarchy is reversed, with the right hemisphere released from inhibition by the left. In support of this model, the available neuroimaging evidence for lateralization under psychedelics is reviewed. Then, various cognitive and emotional changes observed under psychedelics are contrasted with those same functions in each hemisphere. These include attention; social and emotional intelligence; creativity and insight; and language. The article concludes with a review of laterality in other ASCs, such as meditative and trance states, and suggests that many phenomena associated with psychedelics, and other ASCs, might be explained by an atypical annealing between the hemispheres toward right hemisphere predominance.