LSD weakens the brain's usual hierarchy of information flow by making neural communication more balanced between sending and receiving signals. Using magnetoencephalography (MEG) data from 16 healthy adults given 75 micrograms of LSD intravenously, researchers measured directed functional connectivity under four conditions (eyes-closed with or without music, eyes-open with or without video). Across the whole brain, LSD reduced the asymmetry of directed connectivity over time. Machine learning classifiers distinguished LSD from placebo more accurately using hierarchy metrics than traditional connectivity measures. These results indicate that LSD flattens the brain's hierarchical information processing by increasing the balance between senders and receivers of neural signals.
A randomized controlled trial investigated how the psychedelic compounds N,N-dimethyltryptamine (DMT) and harmine, administered during a meditation retreat, affect brain connectivity. Using resting-state fMRI, the study found that these compounds altered functional connectivity in neural networks, particularly in regions associated with self-referential thought and sensory integration. The changes in brain communication patterns were linked to enhanced psychological well-being and mental flexibility, suggesting that combining psychedelics with contemplative practices may promote neuroplasticity and cognitive enhancement. The results indicate that DMT and harmine can reorganize brain networks in ways that support meditative experiences and long-term benefits for brain health.