How to Change Your Mind

by Michael Pollan

  “If the only way we can access the unconscious is via dreams and free association,” he explained the first time we talked, “we aren’t going to get anywhere. Surely there must be something else.” One day he asked his seminar professor if that something else might be a drug. (I asked Robin if his hunch was based on personal experience or research, but he made clear this was not a subject he wished to discuss.) His professor sent him to read a book called Realms of the Human Unconscious by Stanislav Grof.

  “I went to the library and read the book cover to cover. I was blown away. That set the course for the rest of my young life.”

  Carhart-Harris, who is a slender, intense young man in a hurry, with a neatly trimmed beard and large pale blue eyes that seldom blink, formulated a plan it would take him a few years to put into motion: he would use psychedelic drugs and modern brain-imaging technologies to build a foundation of hard science beneath the edifice of psychoanalysis. “Freud said dreams were the royal road to the unconscious,” he reminded me. “Psychedelics could turn out to be the superhighway.” Carhart-Harris’s demeanor is modest, even humble, offering no clue to the audacity of his ambition. He likes to quote Grof’s grand claim that what the telescope was for astronomy, or the microscope for biology, psychedelics will be for understanding the mind.

  Carhart-Harris completed his master’s in psychoanalysis in 2005 and began to plot his move into the neuroscience of psychedelics. He asked around and did some Internet research that eventually led him to David Nutt and Amanda Feilding as two people who might be interested in his project and in a position to help. He first approached Feilding, who in 1998 had established something called the Beckley Foundation to study the effects of psychoactive substances on the brain and to lobby for drug policy reform. The foundation is named for Beckley Park, the sprawling fourteenth-century Tudor manor where she grew up in Oxfordshire and where, in 2005, she invited Carhart-Harris to lunch. (On a recent visit of my own to Beckley, I counted two towers and three moats.)

  Amanda Feilding, who was born in 1943, is an eccentric as only the English aristocracy can breed them. (She’s descended from the house of Habsburg and two of Charles II’s illegitimate children.) A student of comparative religion and mysticism, Feilding has had a long-standing interest in altered states of consciousness and, specifically, the role of blood flow to the brain, which in Homo sapiens, she believes, has been compromised ever since our species began standing upright. LSD, Feilding believes, enhances cognitive function and facilitates higher states of consciousness by increasing cerebral circulation. A second way to achieve a similar result is by means of the ancient practice of trepanation. This deserves a brief digression.

  Trepanation involves drilling a shallow hole in the skull supposedly to improve cerebral blood circulation; in effect, it reverses the fusing of the cranial bones that happens in childhood. Trepanation was for centuries a common medical procedure, to judge by the number of ancient skulls that have turned up with neat holes in them. Convinced that trepanation would help facilitate higher states of consciousness, Feilding went looking for someone to perform the operation on her. When it became clear no professional would oblige, she trepanned herself in 1970, boring a small hole in the middle of her forehead with an electric drill. (She documented the procedure in a short but horrifying film called Heartbeat in the Brain.) Pleased with the results, Feilding went on to stand for election to Parliament, twice, on a platform of “Trepanation for the National Health.”

  But while Amanda Feilding may be eccentric, she is by no means feckless. Her work on both drug research and drug policy reform has been serious, strategic, and productive. In recent years, her focus has shifted from trepanation to the potential of psychedelics to improve brain function. In her own life, she has used LSD as a kind of “brain tonic,” favoring a daily dose that hits “that sweet spot where creativity and enthusiasm is increased, but control is maintained.” (She told me that there was a time when she put that tonic dose at 150 micrograms—far above a microdose and enough to send most people, myself included, on a full-fledged trip. But because frequent use of LSD can lead to tolerance, it’s entirely possible that for some people 150 micrograms merely “adds a certain sparkle to consciousness.”) I found Feilding to be disarmingly frank about the baggage she brings to the new conversation about psychedelic science: “I’m a druggie. I live in this big house. And I have a hole in my head. I guess that disqualifies me.”

  So, when an aspiring young scientist named Robin Carhart-Harris came for lunch at Beckley in 2005, sharing his ambition to combine research into LSD and Freud, Feilding immediately saw the potential, as well as an opportunity to put her theories about cerebral blood circulation to the test. Feilding indicated to Carhart-Harris that her foundation might be willing to fund such research and suggested that he contact David Nutt, then a professor at the University of Bristol and an ally of Feilding’s in the campaign to reform drug policy.

  In his own way, David Nutt is as notorious in England as Amanda Feilding. Nutt, who is a large, jolly fellow in his sixties with a mustache and a booming laugh, achieved his particular notoriety in 2009. That’s when the home secretary fired him from the government’s Advisory Council on the Misuse of Drugs, of which he had been chair. The committee is charged with advising the government on the classification of illicit drugs based on their risk to individuals and society. Nutt, who is an expert on addiction and on the class of drugs called benzodiazepines (such as Valium), had committed the fatal political error of quantifying empirically the risks of various psychoactive substances, both legal and illegal. He had concluded from his research, and would tell anyone who asked, that alcohol was more dangerous than cannabis and that using Ecstasy was safer than riding a horse.

  “But the sentence that got me sacked,” he told me when we met in his office at Imperial, “was when I went on live breakfast television. I was asked, ‘You’re not seriously telling us that LSD is less harmful than alcohol, are you?’ Of course I am!”*

  Robin Carhart-Harris came to see David Nutt in 2005, hoping to study psychedelics and dreaming under him at Bristol; trying to be strategic, he mentioned the possibility of funding from Feilding. As Carhart-Harris recalls the interview, Nutt was blunt in his dismissal: “‘The idea you want to do is incredibly far-fetched, you have no neuroscience experience, it’s completely unrealistic.’ But I told him I put all my eggs in this basket.” Impressed by the young man’s determination, Nutt made him an offer: “Come do a PhD with me. We’ll start with something straightforward”—this turned out to be the effect of MDMA on the serotonin system—“and then maybe later on we can do psychedelics.”

  “Later on” came in 2009, when Carhart-Harris, armed with a PhD and working in Nutt’s lab with funding from Amanda Feilding, received approval (from the National Health Service and the Home Office) to study the effect of psilocybin on the brain. (LSD would come a few years later.) Carhart-Harris put himself forward as the first volunteer. “If you’re going to give this drug to people and put them in a scanner, I thought, the honest thing is to do it first to yourself.” But, as he told Nutt, “I have an anxious disposition, and may not have been in the best place psychologically, so he dissuaded me; he also thought participating in the experiment might compromise my objectivity.” In the end, a colleague became the first volunteer to receive an injection of psilocybin and then slide into an fMRI scanner to have his tripping brain imaged.

  Carhart-Harris’s working hypothesis was that their brains would exhibit increases in activity, particularly in the emotion centers. “I thought it would look like the dreaming brain,” he told me. Employing a different scanning technology, Franz Vollenweider had published data indicating that psychedelics stimulated brain activity, especially in the frontal lobes. (An area responsible for executive and other higher cognitive functions.) But when the first set of data came in, Carhart-Harris got a surprise: “We were seeing decreases in blood flow”—blood flow being o
ne of the proxies for brain activity that fMRI measures. “Had we made a mistake? It was a real head-scratcher.” But the initial data on blood flow was corroborated by a second measure that looks at changes in oxygen consumption to pinpoint areas of elevated brain activity. Carhart-Harris and his colleagues had discovered that psilocybin reduces brain activity, with the falloff concentrated in one particular brain network that at the time he knew little about: the default mode network.

  Carhart-Harris began reading up on it. The default mode network, or DMN, was not known to brain science until 2001. That was when Marcus Raichle, a neurologist at Washington University, described it in a landmark paper published in the Proceedings of the National Academy of Sciences, or PNAS. The network forms a critical and centrally located hub of brain activity that links parts of the cerebral cortex to deeper (and older) structures involved in memory and emotion.*

  The discovery of the default mode network was actually a scientific accident, a happy by-product of the use of brain-imaging technologies in brain research.* The typical fMRI experiment begins by establishing a “resting state” baseline for neural activity as the volunteer sits quietly in the scanner awaiting whatever tests the researcher has in store. Raichle had noticed that several areas in the brain exhibited heightened activity precisely when his subjects were doing nothing mentally. This was the brain’s “default mode,” the network of brain structures that light up with activity when there are no demands on our attention and we have no mental task to perform. Put another way, Raichle had discovered the place where our minds go to wander—to daydream, ruminate, travel in time, reflect on ourselves, and worry. It may be through these very structures that the stream of our consciousness flows.

  The default network stands in a kind of seesaw relationship with the attentional networks that wake up whenever the outside world demands our attention; when one is active, the other goes quiet, and vice versa. But as any person can tell you, quite a lot happens in the mind when nothing much is going on outside us. (In fact, the DMN consumes a disproportionate share of the brain’s energy.) Working at a remove from our sensory processing of the outside world, the default mode is most active when we are engaged in higher-level “metacognitive” processes such as self-reflection, mental time travel, mental constructions (such as the self or ego), moral reasoning, and “theory of mind”—the ability to attribute mental states to others, as when we try to imagine “what it is like” to be someone else. All these functions may belong exclusively to humans, and specifically to adult humans, for the default mode network isn’t operational until late in a child’s development.

  “The brain is a hierarchical system,” Carhart-Harris explained in one of our interviews. “The highest-level parts”—those developed late in our evolution, typically located in the cortex—“exert an inhibitory influence on the lower-level [and older] parts, like emotion and memory.” As a whole, the default mode network exerts a top-down influence on other parts of the brain, many of which communicate with one another through its centrally located hub. Robin has described the DMN variously as the brain’s “orchestra conductor,” “corporate executive,” or “capital city,” charged with managing and “holding the whole system together.” And with keeping the brain’s unrulier tendencies in check.

  The brain consists of several different specialized systems—one for visual processing, for example, another to control motor activity—each doing its own thing. “Chaos is averted because all systems are not created equal,” Marcus Raichle has written. “Electrical signaling from some brain areas takes precedence over others. At the top of this hierarchy resides the DMN, which acts as an uber-conductor to ensure that the cacophony of competing signals from one system do not interfere with those from another.” The default mode network keeps order in a system so complex it might otherwise descend into the anarchy of mental illness.

  As mentioned, the default mode network appears to play a role in the creation of mental constructs or projections, the most important of which is the construct we call the self, or ego.* This is why some neuroscientists call it “the me network.” If a researcher gives you a list of adjectives and asks you to consider how they apply to you, it is your default mode network that leaps into action. (It also lights up when we receive “likes” on our social media feeds.) Nodes in the default network are thought to be responsible for autobiographical memory, the material from which we compose the story of who we are, by linking our past experiences with what happens to us and with projections of our future goals.

  The achievement of an individual self, a being with a unique past and a trajectory into the future, is one of the glories of human evolution, but it is not without its drawbacks and potential disorders. The price of the sense of an individual identity is a sense of separation from others and nature. Self-reflection can lead to great intellectual and artistic achievement but also to destructive forms of self-regard and many types of unhappiness. (In an often-cited paper titled “A Wandering Mind Is an Unhappy Mind,” psychologists identified a strong correlation between unhappiness and time spent in mind wandering, a principal activity of the default mode network.) But, accepting the good with the bad, most of us take this self as an unshakable given, as real as anything we know, and as the foundation of our life as conscious human beings. Or at least I always took it that way, until my psychedelic experiences led me to wonder.

  Perhaps the most striking discovery of Carhart-Harris’s first experiment was that the steepest drops in default mode network activity correlated with his volunteers’ subjective experience of “ego dissolution.” (“I existed only as an idea or concept,” one volunteer reported. Recalled another, “I didn’t know where I ended and my surroundings began.”) The more precipitous the drop-off in blood flow and oxygen consumption in the default network, the more likely a volunteer was to report the loss of a sense of self.*

  Shortly after Carhart-Harris published his results in a 2012 paper in PNAS (“Neural Correlates of the Psychedelic State as Determined by fMRI Studies with Psilocybin”*), Judson Brewer, a researcher at Yale* who was using fMRI to study the brains of experienced meditators, noticed that his scans and Robin’s looked remarkably alike. The transcendence of self reported by expert meditators showed up on fMRIs as a quieting of the default mode network. It appears that when activity in the default mode network falls off precipitously, the ego temporarily vanishes, and the usual boundaries we experience between self and world, subject and object, all melt away.

  This sense of merging into some larger totality is of course one of the hallmarks of the mystical experience; our sense of individuality and separateness hinges on a bounded self and a clear demarcation between subject and object. But all that may be a mental construction, a kind of illusion—just as the Buddhists have been trying to tell us. The psychedelic experience of “non-duality” suggests that consciousness survives the disappearance of the self, that it is not so indispensable as we—and it—like to think. Carhart-Harris suspects that the loss of a clear distinction between subject and object might help explain another feature of the mystical experience: the fact that the insights it sponsors are felt to be objectively true—revealed truths rather than plain old insights. It could be that in order to judge an insight as merely subjective, one person’s opinion, you must first have a sense of subjectivity. Which is precisely what the mystic on psychedelics has lost.

  The mystical experience may just be what it feels like when you deactivate the brain’s default mode network. This can be achieved any number of ways: through psychedelics and meditation, as Robin Carhart-Harris and Judson Brewer have demonstrated, but perhaps also by means of certain breathing exercises (like holotropic breathwork), sensory deprivation, fasting, prayer, overwhelming experiences of awe, extreme sports, near-death experiences, and so on. What would scans of brains in the midst of those activities reveal? We can only speculate, but quite possibly we would see the same quieting of the default mode network Brewer and
Carhart-Harris have found. This quieting might be accomplished by restricting blood flow to the network, or by stimulating the serotonin 2A receptors in the cortex, or by otherwise disturbing the oscillatory rhythms that normally organize the brain. But however it happens, taking this particular network off-line may give us access to extraordinary states of consciousness—moments of oneness or ecstasy that are no less wondrous for having a physical cause.

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  • • •

  IF THE DEFAULT MODE network is the conductor of the symphony of brain activity, you would expect its temporary absence from the stage to lead to an increase in dissonance and mental disorder—as indeed appears to happen during the psychedelic journey. In a series of subsequent experiments using a variety of brain-imaging techniques, Carhart-Harris and his colleagues began to study what happens elsewhere in the neural orchestra when the default mode network puts down its baton.

  Taken as a whole, the default mode network exerts an inhibitory influence on other parts of the brain, notably including the limbic regions involved in emotion and memory, in much the same way Freud conceived of the ego keeping the anarchic forces of the unconscious id in check. (David Nutt puts the matter bluntly, claiming that in the DMN “we’ve found the neural correlate for repression.”) Carhart-Harris hypothesizes that these and other centers of mental activity are “let off the leash” when the default mode leaves the stage, and in fact brain scans show an increase in activity (as reflected by increases in blood flow and oxygen consumption) in several other brain regions, including the limbic regions, under the influence of psychedelics. This disinhibition might explain why material that is unavailable to us during normal waking consciousness now floats to the surface of our awareness, including emotions and memories and, sometimes, long-buried childhood traumas. It is for this reason that some scientists and psychotherapists believe psychedelics can be profitably used to surface and explore the contents of the unconscious mind.