A new study published last month examined the influence of LSD on brain connections, yielding some enlightening results.
The study, published in the Journal of Psychopharmacology, found that the “drug not only increases the strength of certain brain connections but weakens other connections at the same time,” according to a digest of the study in Psychedelic Spotlight.
In the abstract of the study, the authors wrote that psychedelics “have emerged as promising candidate treatments for various psychiatric conditions, and given their clinical potential, there is a need to identify biomarkers that underlie their effects.”
“Here, we investigate the neural mechanisms of lysergic acid diethylamide (LSD) using regression dynamic causal modelling (rDCM), a novel technique that assesses whole-brain effective connectivity (EC) during resting-state functional magnetic resonance imaging (fMRI),” they wrote.
The study involved 45 participants who “were administered 100 μg LSD and placebo in two resting-state fMRI sessions.”
“We compared EC against whole-brain functional connectivity (FC) using classical statistics and machine learning methods. Multivariate analyses of EC parameters revealed predominantly stronger interregional connectivity and reduced self-inhibition under LSD compared to placebo, with the notable exception of weakened interregional connectivity and increased self-inhibition in occipital brain regions as well as subcortical regions,” the authors wrote. “Together, these findings suggests that LSD perturbs the Excitation/Inhibition balance of the brain. Notably, whole-brain EC did not only provide additional mechanistic insight into the effects of LSD on the Excitation/Inhibition balance of the brain, but EC also correlated with global subjective effects of LSD and discriminated experimental conditions in a machine learning-based analysis with high accuracy (91.11%), highlighting the potential of using whole-brain EC to decode or predict subjective effects of LSD in the future.”
The shifting attitudes toward psychedelics has led to a reassessment of anti-drug laws and medical treatments. As the authors of the study said, “psilocybin and lysergic acid diethylamide (LSD) have emerged as promising new treatment candidates for a variety of psychiatric conditions including substance dependence, major depression, anxiety disorders, and adjustment disorders.”
So, what did they learn?
Per Psychedelic Spotlight, the “study found that LSD enhances connectivity across widespread brain networks,” specifically that “LSD increased integration between the visual processing center of the brain (the lingual gyrus) and the region involved in self-awareness and introspection (the inferior frontal gyrus).”
“By strengthening connections between these brain regions, LSD appears to allow for new creative associations and altered states of consciousness,” the article said.
“However, the researchers also found there are weaker connections in certain areas of the occipital cortex, putamen, and cerebellum. The study revealed that LSD alters the brain’s connectivity, impacting the strength of communication between various regions. The intensity of these altered connections correlated with the psychological experiences reported by participants, indicating that the perceptual effects of LSD are rooted in the drug’s modulation of inter-regional brain signaling. The results suggest LSD’s psychedelic effects arise from changes in the brain’s functional organization, not localized activation. In other words, LSD affects the way different regions of the brain communicate with each other,” Psychedelic Spotlight’s write-up continued.
“Using sophisticated neuroimaging techniques, the researchers probed the inner workings of the resting brain. Functional connectivity analysis tracked the coordination of activity across brain regions, revealing how they form an integrated network even in the absence of focused thought or external stimuli. A statistical technique called partial least squares correlation analysis identified relationships between brain networks and psychological states, illuminating the neural foundations of our waking consciousness. Through these innovative analytical approaches, the study yielded fresh insights into the brain’s intrinsic dynamics.”
