How to Change Your Mind

network has the potential to help relieve several forms of mental illness,
including the handful of disorders psychedelic researchers have trialed so
far.
So many of the volunteers I spoke to, whether among the dying, the
addicted, or the depressed, described feeling mentally “stuck,” captured
in ruminative loops they felt powerless to break. They talked about
“prisons of the self,” spirals of obsessive introspection that wall them off
from other people, nature, their earlier selves, and the present moment.
All these thoughts and feelings may be the products of an overactive
default mode network, that tightly linked set of brain structures
implicated in rumination, self-referential thought, and metacognition—
thinking about thinking. It stands to reason that by quieting the brain
network responsible for thinking about ourselves, and thinking about
thinking about ourselves, we might be able to jump that track, or erase it
from the snow.
The default mode network appears to be the seat not only of the ego,
or self, but of the mental faculty of time travel as well. The two are of
course closely related: without the ability to remember our past and
imagine a future, the notion of a coherent self could hardly be said to
exist; we define ourselves with reference to our personal history and
future objectives. (As meditators eventually discover, if we can manage to
stop thinking about the past or future and sink into the present, the self
seems to disappear.) Mental time travel is constantly taking us off the
frontier of the present moment. This can be highly adaptive; it allows us
to learn from the past and plan for the future. But when time travel turns
obsessive, it fosters the backward-looking gaze of depression and the
forward pitch of anxiety. Addiction, too, seems to involve uncontrollable
time travel. The addict uses his habit to organize time: When was the last
hit, and when can I get the next?
To say the default mode network is the seat of the self is not a simple
proposition, especially when you consider that the self may not be exactly
real. Yet we can say there is a set of mental operations, time travel among
them, that are associated with the self. Think of it simply as the locus of
this particular set of mental activities, many of which appear to have their
home in the structures of the default mode network.
Another type of mental activity that neuroimaging has located in the
DMN (and specifically in the posterior cingulate cortex) is the work