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A large international team of researchers, including Prof Morten Kringelbach at the University of Oxford's Department of Psychiatry, have uncovered changes in whole-brain dynamics caused by LSD.

Lsd crop

LSD (lysergic acid diethylamide) was initially synthetized by Albert Hofmann in 1938 to stimulate the respiratory and circulatory systems. Yet, it was 5 years later that he accidentally discovered the profound effects of LSD on perception and consciousness, which led to its extensive use as a research and therapeutic tool in psychiatry in the 1950s. Today, LSD and related psychedelics are considered by some to be ‘microscopes’ or ‘telescopes’ for the psyche, because they reveal more of the mind than is normally accessible. However, the brain mechanisms underlying LSD’s profound effects have remained largely elusive.

According to a study published December 15, 2017 in the open-access journal Scientific Reports, led by Dr Selen Atasoy, Prof Morten Kringelbach, Prof Gustavo Deco and Dr Robin Carhart-Harris from the Universities of Pompeu Fabra (Spain), Oxford (UK), Aarhus (Denmark) and Imperial College London (UK), the effects of LSD on whole-brain dynamics can now be understood.

By revealing the characteristic differences between LSD and normal awake state, the applied harmonic wave decomposition opens-up the possibility of extracting the signatures of various mental states, including sleep, anesthesia, and disorders of consciousness as well as psychiatric and neurological disorders.
- Professor Morten Kringelbach

To decode the effects of LSD in the brain, the team has used a novel harmonic language of brain activity, which was firstly introduced in a Nature Communications publication in January 2016. This harmonic decoding of fMRI data showed that LSD increases the total energy and enriches the repertoire of connectome harmonics - the basic elements of this harmonic language. The research also revealed that LSD selectively activated high-frequency connectome harmonics, which remarkably caused the brain activity to self-organize right at the edge of chaos.

Dr Selen Atasoy, the lead author of the study says: “The connectome harmonics we used to decode brain activity are universal harmonic waves, such as sound waves emerging within a musical instrument, but adapted to the anatomy of the brain. Translating fMRI data into this harmonic language is actually not different than decomposing a complex musical piece into its musical notes”. “What LSD does to your brain seems to be similar to jazz improvisation” says Atasoy, “your brain combines many more of these harmonic waves (connectome harmonics) spontaneously yet in a structured way, just like improvising jazz musicians play many more musical notes in a spontaneous, non-random fashion”.

“The presented method introduces a new paradigm to study brain function, one that links space and time in brain activity via the universal principle of harmonic waves. It also shows that this spatio-temporal relation in brain dynamics resides at the transition between order and chaos.” says Prof Gustavo Deco.

Dr. Robin Carhart-Harris adds: “Our findings reveal the first experimental evidence that LSD tunes brain dynamics closer to criticality, a state that is maximally diverse and flexible while retaining properties of order. This may explain the unusual richness of consciousness experienced under psychedelic drugs and the notion that they ‘expand consciousness’.” 

Read the full paper: 'Connectome-harmonic decomposition of human brain activity reveals dynamical repertoire re-organization under LSD' in Scientific Report.