Increased brain signal diversity in the psychedelic state

A new study from our group, performed in collaboration with Robin Carhart-Harris (Imperial College London) and Suresh Muthukumaraswamy (University of Auckland), describes a distinctive new brain signature of the psychedelic state. With Michael Schartner and Adam Barrett from the Sackler Centre, we computed the 'diversity' of MEG brain signals both at a normal waking 'baseline' and while volunteers were under the influence of either psylocibin, ketamine, or LSD.

We found reliable increases in signal diversity across all three psychedelic conditions. This is striking since this measure has previously only shown decreases from the waking baseline, in conditions like sleep and anesthesia. While this does not entail any 'scientific demonstration' of a 'higher state of consciousness', it does help us understand how and why psychedelic compounds give rise to unusual conscious experiences. In the longer term, our findings will help improve our understanding of how the brain generates conscious experiences in the normal - non-psychedelic - condition, and it may also help the rapidly growing research into the potential clinical benefits of these compounds in psychiatry.

I've written an 'explainer' blog post here, which goes a bit more into the background and significance. See also an excellent Guardian piece on the research here. The official Sussex press release is here.

The paper appeared in Scientific Reports on April 19, 2017, coincidentally 74 years to the day after Albert Hoffman's first self-experiments with LSD, an occasion now known as 'bicycle day'. It is freely available here. The full reference is: Schartner, M., Cahart-Harris, R., Barrett, A.B., Seth, A.K.*, and Muthukumaraswamy, S. (2017). Increased spontaneous MEG signal diversity for psychoactive doses of ketamine, LSD, and psylocibin. Scientific Reports. 7:46421 (*corresponding author)

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