Luke Williams - Affinity & Efficacy: The Molecular Neuropharmacology of Psychedelics

Psychedelic substances act as serotonin receptor ligands, with the 5-HT2A receptor identified as the primary target mediating their psychoactive effects. This presentation contrasts the molecular interactions and potencies of classic psychedelics, emphasizing the concept of receptor affinity versus efficacy. Differences in molecular structure, such as the alpha-methyl group found in certain phenethylamines, significantly influence potency and subjective experience. Research highlights the activation of intracellular signaling pathways, specifically those triggered by G-proteins and secondary messengers after drug receptor binding. These complex cascades affect neuronal activity at a local level, with speculative implications for downstream changes in global brain activity. The speaker notes the limitations of animal models in fully capturing the human psychedelic experience and the need for more nuanced understandings of how these signaling pathways correlate with subjective states.