How to Change Your Mind: What the New Science of Psychedelics Teaches Us About Consciousness, Dying, Addiction, Depression, and Transcendence

by Michael Pollan

“is that the mushrooms that produced the most psilocybin got selectively eaten and so their spores got more widely disseminated.”

Beug says that many animals are known to eat psilocybin mushrooms, including horses, cattle, and dogs. Some, like cows, appear unaffected, but many animals appear to enjoy an occasional change in consciousness too. Beug is in charge of gathering mushroom-poisoning reports for the North American Mycological Association and over the years has seen accounts of horses tripping in their paddocks and dogs that “zero in on Psilocybes and appear to be hallucinating.” Several primate species (aside from our own) are also known to enjoy psychedelic mushrooms. Presumably animals with a taste for altered states of consciousness have helped spread psilocybin far and wide.

Eaten in small doses, psychedelic mushrooms might well increase fitness in animals, by increasing sensory acuity and possibly focus as well.

“Plants and mushrooms have intelligence, and they want us to take care of the environment, and so they communicate that to us in a way we can understand.”

Mushrooms have taught me the interconnectedness of all life-forms and the molecular matrix that we share,”

“realized being” as simply a person with “an acute sense of the astonishing mystery of everything.”

For many of the alcoholics treated at Weyburn hospital, the core of the LSD experience seemed to involve something closer to transcendence, or spiritual epiphany, than temporary psychosis.

branch of sage and a stub of Palo Santo, a fragrant South American wood that Indians burn ceremonially, and the jet-black

True, one had to favor doing in order to get anything done, but wasn’t there also a great virtue and psychic benefit in simply being? In contemplation rather than action?

I decided I needed to practice being with stillness, being with other people as I find them (imperfect), and being with my own unimproved self. To savor whatever is at this very moment, without trying to change it or even describe it. (Huxley struggled with the same aspiration during his mescaline journey: “If one always saw like this, one would never want to do anything else.”)

Not only was the flood of love she experienced ineffably powerful, but it was unattributable to any individual or worldly cause, and so was purely gratuitous—a form of grace. So how to convey the magnitude of such a gift? “God” might be the only word in the language big enough.

According to scholars of mysticism, these shared traits generally include a vision of unity in which all things, including the self, are subsumed (expressed in the phrase “All is one”); a sense of certainty about what one has perceived (“Knowledge has been revealed to me”); feelings of joy, blessedness, and satisfaction; a transcendence of the categories we rely on to organize the world, such as time and space or self and other; a sense that whatever has been apprehended is somehow sacred (Wordsworth: “Something far more deeply interfused” with meaning) and often paradoxical (so while the self may vanish, awareness abides). Last is the conviction that the experience is ineffable, even as thousands of words are expended in the attempt to communicate its power. (Guilty.)

The journeys have shown me what the Buddhists try to tell us but I have never really understood: that there is much more to consciousness than the ego, as we would see if it would just shut up.

And that its dissolution (or transcendence) is nothing to fear; in fact, it is a prerequisite for making any spiritual progress.

But the ego, that inner neurotic who insists on running the mental show, is wily and doesn’t relinquish its power without a struggle. Deeming itself indispensable, it will battle against its diminishme...

That stingy, vigilant security guard admits only the narrowest bandwidth of reality, “a measly trickle of the kind of consciousness which will help us to stay alive.”

It’s really good at performing all those activities that natural selection values: getting ahead, getting liked and loved, getting fed, getting laid. Keeping us on task, it is a ferocious editor of anything that might distract us from the work at hand, whether that means regulating our access to memories and strong emotions from within or news of the world without.

psilocin, LSD, and 5-MeO-DMT—but

All three molecules are tryptamines.

Living nature is awash in tryptamines, which show up in plants, fungi, and animals, where they typically act as signaling molecules between cells. The most famous tryptamine in the human body is the neurotransmitter serotonin, the chemical name of which is 5-hydroxytryptamine.

The group of tryptamines we call “the classic psychedelics” have a strong affinity with one particular type of serotonin receptor, called the 5-HT2A

These receptors are found in large numbers in the human cortex, the outermost, and evolutionarily most recent, layer of the brain. Basically, the psychedelics resemble serotonin closely enough that they can attach themselves to this receptor site in such a way as to activate it to do various things.

What neuroscientists and philosophers and psychologists mean by consciousness is the unmistakable sense we have that we are, or possess, a self that has experiences.

Thomas Nagel, a philosopher, in a famous 1974 paper, “What Is It Like to Be a Bat?” He argued that if “there is something that it is like to be a bat”—if there is any subjective dimension to bat experience—then a bat possesses consciousness. He went on to suggest that this “what it is like” quality may not be reducible to material terms. Ever.

A psychedelic drug is powerful enough to disrupt the system we call normal waking consciousness in ways that may force some of its fundamental properties into view.

True, anesthetics disrupt consciousness too, yet because such drugs shut it down, this kind of disturbance yields relatively little data.

His professor sent him to read a book called Realms of the Human Unconscious by Stanislav Grof.

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.

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.

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.

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 ...

“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,

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.

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.”

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.

Self-reflection can lead to great intellectual and artistic achievement but also to destructive forms of self-regard and many types of unhappiness.

“A Wandering Mind Is an Unhappy Mind,”

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.

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 an...

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,...

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.

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, overwhelmi...

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.

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.

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.