LSD flattens the hierarchy of directed information flow in fast whole-brain dynamics.
Imaging Neurosci (Camb) January 3, 2025 Kenneth Shinozuka, Prejaas K.b. Tewarie, Andrea Luppi et al. 9 citations
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.