Human neuroimaging: fMRI.

Human neuroimaging with functional Magnetic Resonance Imaging has been a key feature of the current wave of psychedelic research, in both healthy and clinical populations. The available data has suggested that classic psychedelics (psilocybin, LSD, DMT) have a characteristic effect of acutely and profoundly disrupting the normal pattern of resting-state connectivity in the human brain, and that this effect may be closely related to both the characteristic subjective phenomenology of psychedelics, and their more clinically-relevant longer-term effects on emotional brain systems. This chapter briefly outlines the basic methodological background of fMRI, and then provides an overview of the current state of knowledge of psychedelic drug action as revealed by task and resting-state fMRI, in both non-clinical and clinical cohorts. Current limitations of the field are largely addressable by ongoing and future work, particularly in terms of providing additional datasets, increased standardisation of data acquisition and analysis procedures, potential multi-modal imaging studies, and more open data-sharing. Neuroimaging with fMRI remains a central platform of modern psychedelic research, with implications for our mechanistic understanding of psychedelics, as well as a strong influence on the clinical development of psychedelic-based treatments.