Michael Pollan explores the neuroscience of psychedelics in this excerpt from his new book.
What does a high-entropy brain look like? The various scanning technologies that an Imperial College lab has used to map the brains of people on psychedelic drugs show that the specialized neural networks of the brain — such as the default mode network and the visual processing system — each become disintegrated, while the brain as a whole becomes more integrated as new connections spring up among regions that ordinarily kept mainly to themselves or were linked only via the central hub of the default mode network. Put another way, the various networks of the brain became less specialized.
“Distinct networks became less distinct under the drug,” Imperial College’s head of psychedelic research, Robin Carhart-Harris, and his colleagues have written, “implying that they communicate more openly” with other brain networks. “The brain operates with greater flexibility and interconnectedness under hallucinogens.”
In a 2014 paper published in the Journal of the Royal Society Interface, the Imperial College team demonstrated how the usual lines of communications within the brain are radically reorganized when the default mode network goes off-line and the tide of entropy is allowed to rise. Using a scanning technique called magnetoencephalography, which maps electrical activity in the brain, the authors produced a map of the brain’s internal communications during normal waking consciousness and after an injection of psilocybin. In its normal state, the brain’s various networks talk mostly to themselves, with a relatively few heavily trafficked pathways among them.
But when the brain operates under the influence of psilocybin, thousands of new connections form, linking far-flung brain regions that during normal waking consciousness don’t exchange much information. In effect, traffic is rerouted from a relatively small number of interstate highways onto myriad smaller roads linking a great many more destinations. The brain appears to become less specialized and more globally interconnected, with considerably more intercourse, or “cross talk,” among its various neighborhoods.
The increase in entropy allows a thousand mental states to bloom, many of them bizarre and senseless, but some number of them revelatory and imaginative.
There are several ways this temporary rewiring of the brain may affect mental experience. When the memory and emotion centers are allowed to communicate directly with the visual processing centers, it’s possible our wishes and fears, prejudices and emotions, begin to inform what we see — a hallmark of primary consciousness and a recipe for magical thinking. Likewise, the establishment of new linkages across brain systems can give rise to synesthesia, as when sense information gets cross-wired so that colors become sounds or sounds become tactile. Or the new links give rise to hallucination, as when the contents of my memory transformed my visual perception of Mary into María Sabina, or the image of my face in the mirror into a vision of my grandfather. The forming of still other kinds of novel connections could manifest in mental experience as a new idea, a fresh perspective, a creative insight, or the ascribing of new meanings to familiar things — or any number of the bizarre mental phenomena people on psychedelics report. The increase in entropy allows a thousand mental states to bloom, many of them bizarre and senseless, but some number of them revelatory, imaginative, and, at least potentially, transformative.
One way to think about this blooming of mental states is that it temporarily boosts the sheer amount of diversity in our mental life. If problem solving is anything like evolutionary adaptation, the more possibilities the mind has at its disposal, the more creative its solutions will be. In this sense, entropy in the brain is a bit like variation in evolution: it supplies the diversity of raw materials on which selection can then operate to solve problems and bring novelty into the world. If, as so many artists and scientists have testified, the psychedelic experience is an aid to creativity — to thinking “outside the box” — this model might help explain why that is the case. Maybe the problem with “the box” is that it is singular.
A key question that the science of psychedelics has not even begun to answer is whether the new neural connections that psychedelics make possible endure in any way, or if the brain’s wiring returns to the status quo ante once the drug wears off. The finding by Roland Griffiths’s lab that the psychedelic experience leads to long-term changes in the personality trait of openness raises the possibility that some kind of learning takes place while the brain is rewired and that it might in some way persist. Learning entails the establishment of new neural circuits; these get stronger the more exercise they get. The long-term fate of the novel connections formed during the psychedelic experience — whether they prove durable or evanescent — might depend on whether we recall and, in effect, exercise them after the experience ends. (This could be as simple as recollecting what we experienced, reinforcing it during the integration process, or using meditation to reenact the altered state of consciousness.)
Franz Vollenweider has suggested that the psychedelic experience may facilitate “neuroplasticity”: it opens a window in which patterns of thought and behavior become more plastic and so easier to change. His model sounds like a chemically mediated form of cognitive behavioral therapy. But so far this is all highly speculative; as yet there has been little mapping of the brain before and after psychedelics to determine what, if anything, the experience changes in a lasting way.
Carhart-Harris argues in the entropy paper that even a temporary rewiring of the brain is potentially valuable, especially for people suffering from disorders characterized by mental rigidity. A high-dose psychedelic experience has the power to “shake the snow globe,” he says, disrupting unhealthy patterns of thought and creating a space of flexibility — entropy — in which more salubrious patterns and narratives have an opportunity to coalesce as the snow slowly resettles.
This article is adapted with permission from How to Change Your Mind, by Michael Pollan, published by Penguin Press, an imprint of Penguin Publishing Group, a division of Penguin Random House LLC. Copyright © 2018 by Michael Pollan.