Lysergic acid diethylamide, better known as LSD, is one of the most powerful psychotropic substances known. It can induce altered states of consciousness, sometimes compared to the states of schizophrenia or the mystique experience. The study of the effects on the brain of psychedelic compounds such as LSD are highly relevant to the study of other psychological traits such as personality, creativity and also for better characterizing neurological and psychiatric diseases.

An article published in December in Scientific Reports applies a powerful new analytical methodology to study the dynamics of brain states in LSD-induced psychedelic states. Among the authors of the study are Gustavo Deco, director of the Center for Brain and Cognition (CBC) and ICREA research professor with the Department of Information and Communication Technologies (DTIC) at UPF, and Selen Atasoy, doctoral researcher with his team and first author of the study.

For the experimental part, twelve individuals took part who were assigned to six possible conditions under study: LSD; placebo; LSD or placebo, while listening to music; LSD or placebo, after the music session. Exploring the combined effects of music and LSD-induced  psychedelic states gave the opportunity to reveal not only the dynamic changes induced by LSD in the brain, but also how these dynamics are affected by the presence of complex and natural stimuli such as music.

The new method, refined by the researchers, has enabled breaking down the data from functional magnetic resonance (fMRI in English) of brains in a state of rest and under the effects of LSD, for a set of independent states. States of intelligence are defined as spatial patterns formed by a completely synchronized activity, each associated with a different spatial wavelength; which the authors call connectome-harmonic.

“The unique decomposition of the cortical activity into a sum of specific frequency states allows us to characterize not only the dominant frequency content of brain activity under LSD and/or placebo, but also the underlying dynamics in terms of frequency distribution among the complete repertoire of these states”, Gustavo Deco comments.

To characterize brain activity during the LSD-induced psychedelic state, the authors focused their evaluation on two fundamental properties of brain states: the power or strength of activation per unit of time according to the fMRI, and the energy or weighted contribution of this activation in the cortical Dynamics. Two parameters that have been found to be altered under the influence of LSD. In addition, LSD has been seen to cause a reorganization of brain dynamics at the critical condition, that is to say, a state located on the edge between two opposite tendencies of neural connection: a quiescent order and a chaotic disorder.

The current findings emphasize the value of the global brain function and the subjective states related in terms of the dynamic activation of the states of the harmonic brain. It is important to note that this harmonic decomposition of the connectome of the cortical activity allows the evaluation of the fundamental properties of the states of the brain, and brings to neurosciences new and innovative tools based on well-studied physical concepts.

Reference article:

Selen Atasoy, Leor Roseman, Mendel Kaelen, Morten L. Kringelbach, Gustavo Deco, Robin L. Carhart-Harris (2017), “Connectome-harmonic decomposition of human brain activity reveals dynamical repertoire re-organization under LSD”, Scientific Reports 7, Article number: 17661, doi:10.1038/s41598-017-17546-0.

Related information appeared in the media:

Shayla Love, “LSD Brings Your Brain to the Edge of Chaos”, 2 de març del 2018, Tonic.