Book of the Week: Being You

In this extract from his new study, neuro-scientist Anil Seth looks at how psychedelics dissolve everyday boundaries

In the psychedelic state, vivid perceptual hallucinations are frequently accompanied by unusual experiences of selfhood often described as “ego dissolution“, where the boundaries between self and world, and other people, appear to shift or dissolve.

These departures from “normal” conscious experience are so pervasive that the psychedelic state might represent not only a change in conscious contents, but also a change in overall conscious level. This is the idea we set out to test, in a collaboration with Robin Carhart-Harris at Imperial College London and Suresh Muthukumaraswamy at the University of Auckland.

In April 2016, Robin and I were at a conference in the foothills of the Santa Catalina mountains, just outside Tucson, in Arizona. We’d both been invited to give talks about our research, and we were using the opportunity to explore how our interests in consciousness might overlap in the context of psychedelics.

Scientific and medical research on LSD, and on other psychedelic compounds like psilocybin (the active ingredient in magic mushrooms), had only recently restarted after decades in the wilderness. Following Hofmann’s self-experimentation there had a been a brief flowering of studies exploring the potential of LSD for treating a range of psychological disorders, including addiction and alcoholism, with very promising results.

But the subsequent uptake of LSD as a recreational drug and as a symbol of rebellion, evangelised by Timothy Leary among others, led to pretty much all of this research being shut down by the end of the 1960s. It took until the 2000s before any substantial new research restarted – a lost generation of scientific progress.

At the level of neurochemistry, the classic psychedelics – LSD, psilocybin, mescaline, and dimethyltryptamine (DMT, the active ingredient in the South American hallucinogenic brew called ayahuasca) – work primarily by affecting the brain’s serotonin system. Serotonin is one of the brain’s primary neurotransmitters – chemicals which wash through the brain’s circuits and which influence how neurons communicate.

Psychedelic drugs influence the serotonin system by binding strongly to a specific serotonin receptor, the 5HT-2A receptor, which is found throughout much of the brain. One of the main challenges for psychedelic research is to understand how these low-level pharmacological interventions alter global patterns of brain activity, so as to deliver profound changes in conscious experience.

Robin’s team had previously discovered that the psychedelic state involves striking alterations in brain dynamics, when compared to a placebo control condition. Networks of brain regions that are usually co-ordinated in their activity – so-called “resting-state networks” – become uncoupled, and other regions that are usually more or less independent become linked.

Overall, the picture is of a breakdown in the patterns of connectivity that characterise the brain under normal conditions. Robin’s idea was that these breakdowns could account for signature features of the psychedelic state, like the dissolution of boundaries between self and world, and the intermingling of the senses.

Robin and I realised that the data he’d been collecting were ideally suited for the algorithmic complexity analyses we’d been applying, with my team at Sussex, to sleep and anaesthesia. In particular, some of their brain scans had been carried out using magnetoencephalography (MEG), which provides the high time resolution and global brain coverage that we needed. They had used MEG to measure brain activity in volunteers who had taken either psilocybin, LSD, or low doses of ketamine. (While high doses of ketamine act as an anaesthetic, low doses have more of a hallucinogenic effect.) We could use this data to ask the question: what happens to measures of conscious level, when conscious contents change as dramatically as they do on a psychedelic trip?
Back at Sussex, Michael Schartner and Adam Barrett calculated the changes in the algorithmic complexity of the MEG signal across many different regions in the brain for all three psychedelic states. The results were clear and surprising: psilocybin, LSD, and ketamine all led to increases when compared to a placebo control.

This was the first time anyone had seen an increase in a measure of conscious level, relative to a baseline of waking rest. All previous manipulations, whether through sleep or anaesthesia or disorders of consciousness, had led to decreases in these measures.

To understand what this result means, remember that the measures of algorithmic complexity we used are best thought of as measures of the randomness, or “signal diversity“, of the brain signals that they are applied to. A fully random sequence will have the highest possible algorithmic complexity, the greatest possible diversity.

Our findings therefore complemented Robin’s previous studies by showing that brain activity in the psychedelic state becomes more random over time, in line with the freewheeling reorganisation of perceptual experience that people frequently report during a trip. They also shed new light on how conscious level and conscious content relate. Here is an example of a measure of conscious level responding to the widespread changes in the contents of consciousness that characterise the psychedelic state. The fact that a measure of conscious level is also sensitive to changes in conscious content makes clear that they are not independent aspects of consciousness.

The results from our psychedelic analyses raised a disturbing prospect. Would maximally random brain activity, as measured by algorithmic complexity, lead to a maximally psychedelic experience? Or to a different “level” of consciousness of some other kind? The extrapolation seems unlikely. A brain with all its neurons firing willy-nilly would seem more likely to give rise to no conscious experience at all, just as free-form jazz at some point stops being music.

The issue here is that algorithmic complexity is a poor approximation to what “being complex” usually means. Intuitively, complexity is not the same as randomness. A more satisfying notion of complexity is as the middle ground between order and disorder – not the extreme point of disorder. It is Nina Simone and Thelonious Monk, not the Bonzo Dog Doo-Dah Band. What happens if we run with this more sophisticated way of thinking about complexity instead?

This extract is from Being You: A New Science of Consciousness by Anil Seth (£9.99, Faber & Faber)

We’ll be chatting to Anil Seth on “A Drink with the Idler”, Thursday 23 February at 6pm London time. Book your tickets here. Free to Idler magazine and Academy subscribers.

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