Lysergic acid diethylamide (LSD) effects have not been studied using modern brain-imaging techniques. Two recent studies investigated brain activity and functional connectivity under the influence of LSD. Tagliazucchi et al. used functional MRI (fMRI) to monitor changes in intrinsic functional connectivity following intravenous administration of LSD. They found that LSD administration resulted in a global increase in functional connectivity. These included the default-mode network (DMN) and the salience network, which are associated with a sense of self, and thus the functional connectivity changes could be relevant to the reduced sense of identity (that is, ego dissolution) that is reported by individuals who take LSD. In the second study, Carhart-Harris et al. used arterial spin labelling, blood oxygen level-dependent (BOLD) measurements and magnetoencephalopathy (MEG) to investigate brain changes induced by LSD. LSD administration increased functional connectivity in visual cortex (compared with a placebo), and this increase was correlated with visual hallucinations. Decreases in connectivity between parahippocampal regions and the retrosplenial cortex were strongly correlated with ratings of ego dissolution. Together, these data reveal patterns of activity that could underlie some of the perceived psychological effects reported by those who take the drug.
Tagliazucchi, E. et al. Increased global functional connectivity correlates with LSD-induced ego dissolution. Curr. Biol. http://dx.doi.org/10.1016/j.cub.2016.02.010 (2016)
Carhart-Harris, R. L. et al. Neural correlates of the LSD experience revealed by multimodal neuroimaging. Proc. Natl Acad. Sci. USA http://dx.doi.org/10.1073/pnas.1518377113 (2016)
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Lewis, S. Getting over yourself. Nat Rev Neurosci 17, 336 (2016). https://doi.org/10.1038/nrn.2016.59