This comprehensive study analyzed three classic psychedelic drugs—LSD, psilocybin (from magic mushrooms), and DMT—across three levels: how people experience them, how they affect brain activity, and how they interact with brain receptors. Researchers found that LSD produces more intense visual experiences than psilocybin, and all three drugs significantly alter brain connectivity patterns. The study highlights the importance of standardizing research methods to better understand how these compounds might help treat depression and addiction.