Proceedings on CD-ROM - International Society for Magnetic Resonance in Medicine. Scientific Meeting and Exhibition/Proceedings of the International Society for Magnetic Resonance in Medicine, Scientific Meeting and Exhibition
Ketamine, a rapid-acting antidepressant, changes functional connectivity in the brain in ways that correlate with the density of receptors known to be involved in depression. In a double-blind placebo-controlled trial, participants received an infusion of ketamine or placebo while undergoing resting-state fMRI. The resulting connectivity changes matched several receptor types linked to depression. This method may help evaluate how new drugs affect the brain.
Psilocybin and lisuride produce a two-phase (bi-phasic) change in cerebral blood volume, while 25CN-NBOH produces a single-phase (monophasic) response. The bi-phasic pattern may stem from the non-selectivity of psilocybin and lisuride. Higher doses of psilocybin cause elevated cerebral blood volume that persists over time, whereas the effects of lisuride and 25CN-NBOH return toward baseline. These findings highlight the sensitivity of pharmacological MRI for evaluating drug effects on brain hemodynamics.
Psilocybin, a serotonergic agonist, and Salvinorin-A, a kappa-opioid receptor agonist, both alter functional connectivity in the brains of non-human primates, but their effects overlap and differ in specific regions. Using fMRI, the study examined how these psychedelics influence connections within the default mode network and the claustrum. The findings suggest that each substance targets distinct receptor systems, leading to both shared and unique patterns of brain network activity, which may help explain their different mechanisms of action.