By Emma Young

Is there anything psychedelic drugs can’t do? A recent wave of scientific scrutiny has revealed that they can elicit “spiritual” experiences, alleviate end-of-life angst, and perhaps treat depression – and they might achieve at least some of all this by “heightening consciousness”, according to a new paper published in the journal Scientific Reports.

A team at the University of Sussex, led by Anil Seth, co-director of the Sackler Centre for Consciousness Science, re-analysed existing magneto-encephalography (MEG) brain imaging data recorded from healthy people who had taken doses of either psilocybin (the psychoactive ingredient in magic mushrooms), LSD or ketamine in the lab and then focused on their ensuing experience. MEG uses magnetic fields at the brain’s surface to identify patterns of neural activity – it’s very sensitive to changes from one moment to the next but not so accurate in terms of locating activity.

Compared with people in a normal waking state, all the dosed-up volunteers, regardless of which drug they’d taken, showed a “sustained increase in neural diversity”. “During the psychedelic state, the electrical activity of the brain is less predictable and less ‘integrated’ than during normal conscious wakefulness – as measured by ‘global signal diversity’,” Seth explained in a press release from the university.

Since this unpredictability and diversity is greater in people who are awake (so who are conscious) than people who are asleep (who are not conscious), the data from people under the influence of psychedelics could be interpreted as signifying an even higher level of consciousness than is experienced during normal wakefulness, the team argued.

The original brain scanning study (that produced the data analysed by the new paper) was led by Robin Carhart-Harris, at Imperial College, London. Carhart-Harris (who is listed a co-author on the new paper) has previously argued that his team’s findings of greater “entropy” – greater disorder – in patterns of brain activity observed in people who had taken psilocybin could be interpreted as evidence in support of the claim that psychedelics can “expand consciousness“.

Whether they heighten it, and/or expand it, the new findings will feed into discussions about the medical and therapeutic uses of these drugs, including in treating PTSD and depression – though it’s still early days for this research.

In the new paper, Seth and colleagues reported a correlation between changes in the diversity of neural signals and the intensity of experiences – such as feelings of floating, of time being distorted, of a disintegration of the self and of sounds influencing vision – reported by the volunteers.

At the moment, it’s not clear which specific changes in brain activity underpin which aspects of the psychedelic experience. But the researchers involved in the new paper are planning work to investigate this.

—Increased spontaneous MEG signal diversity for psychoactive doses of ketamine, LSD and psilocybin

Emma Young (@EmmaELYoung) is Staff Writer at BPS Research Digest