Researchers have long suspected that the altered perception, kaleidoscopic visions and mood changes produced by psych­edelic drugs reflect a jump in brain activity. Not so, say neuroscientists at Imperial College London and elsewhere. They used functional MRI to peek at the brains of 30 participants experiencing a “trip” induced by intravenously delivered psilocybin, a psychedelic found in magic mushrooms. As they reported in the Proceedings of the National Academy of Sciences USA online in January, investigators saw psilocybin-related dips in brain activity, particularly in control centers such as the thalamus, the anterior and posterior cingulate cortices, and the medial prefrontal cortex. The more placid these regions appeared in a participant’s brain, the more intense the subject’s self-reported psychedelic experiences. The scientists conclude that psychedelics temporarily flip off cognition-constraining pathways—including some that are overactive during depression. [For more on this study, click here.]

This article was published in print as "Free Your Mind."