How to Change Your Mind

“Think of psychedelics as temporarily flattening the snow. The deeply
worn trails disappear, and suddenly the sled can go in other directions,
exploring new landscapes and, literally, creating new pathways.” When
the snow is freshest, the mind is most impressionable, and the slightest
nudge—whether from a song or an intention or a therapist’s suggestion—
can powerfully influence its future course.
Robin Carhart-Harris’s theory of the entropic brain represents a
promising elaboration on this general idea, and a first stab at a unified
theory of mental illness that helps explain all three of the disorders we’ve
examined in these pages. A happy brain is a supple and flexible brain, he
believes; depression, anxiety, obsession, and the cravings of addiction are
how it feels to have a brain that has become excessively rigid or fixed in
its pathways and linkages—a brain with more order than is good for it. On
the spectrum he lays out (in his entropic brain article) ranging from
excessive order to excessive entropy, depression, addiction, and disorders
of obsession all fall on the too-much-order end. (Psychosis is on the
entropy end of the spectrum, which is why it probably doesn’t respond to
psychedelic therapy.)
The therapeutic value of psychedelics, in Carhart-Harris’s view, lies in
their ability to temporarily elevate entropy in the inflexible brain, jolting
the system out of its default patterns. Carhart-Harris uses the metaphor
of annealing from metallurgy: psychedelics introduce energy into the
system, giving it the flexibility necessary for it to bend and so change. The
Hopkins researchers use a similar metaphor to make the same point:
psychedelic therapy creates an interval of maximum plasticity in which,
with proper guidance, new patterns of thought and behavior can be
learned.
All these metaphors for brain activity are just that—metaphors—and
not the thing itself. Yet the neuroimaging of tripping brains that’s been
done at Imperial College (and that has since been replicated in several
other labs using not only psilocybin but also LSD and ayahuasca) has
identified measurable changes in the brain that lend credence to these
metaphors. In particular, the changes in activity and connectivity in the
default mode network on psychedelics suggest it may be possible to link
the felt experience of certain types of mental suffering with something
observable—and alterable—in the brain. If the default mode network does
what neuroscientists think it does, then an intervention that targets that