Functional imaging studies of acute administration of classic psychedelics, ketamine, and MDMA: Methodological limitations and convergent results.
Neuroscience and biobehavioral reviews – November 01, 2023
Source: PubMed
Summary
Brain scans reveal that psychedelics like psilocybin and LSD consistently alter connectivity between sensory and cognitive brain regions. Using functional magnetic resonance imaging (FMRI), researchers analyzed 91 studies examining how ketamine, MDMA, and other psychedelics affect brain function. Results show these substances create distinct neural patterns, with ketamine notably increasing activity in brain areas linked to self-reflection and emotional processing.
Abstract
Functional magnetic resonance imaging (fMRI) is increasingly used to non-invasively study the acute impact of psychedelics on the human brain. While fMRI is a promising tool for measuring brain function in response to psychedelics, it also has known methodological challenges. We conducted a systematic review of fMRI studies examining acute responses to experimentally administered psychedelics in order to identify convergent findings and characterize heterogeneity in the literature. We reviewed 91 full-text papers; these studies were notable for substantial heterogeneity in design, task, dosage, drug timing, and statistical approach. Data recycling was common, with 51 unique samples across 91 studies. Fifty-seven studies (54%) did not meet contemporary standards for Type I error correction or control of motion artifact. Psilocybin and LSD were consistently reported to moderate the connectivity architecture of the sensorimotor-association cortical axis. Studies also consistently reported that ketamine administration increased activation in the dorsomedial prefrontal cortex. Moving forward, use of best practices such as pre-registration, standardized image processing and statistical testing, and data sharing will be important in this rapidly developing field.