Psychedelic drugs may exert their effects at intracellular serotonin receptors that serotonin itself, which does not cross cell membranes, cannot reach. The findings were published in the Feb. 17, 2023, issue of Science by researchers from the University of California at Davis. An accompanying editorial by Evan Hess and Todd Gould at the University of Maryland School of Medicine called them “a key achievement in the understanding of the mechanism of action of psychedelics” and “an important step forward for a rapidly ex­panding and much-needed field of study.”