"This repetitive, unproductive thinking, or "faux problem solving," is known in the field of psychiatry as "rumination."
According to Harvard's Rosenbaum, rumination plays a key role in mental health conditions like depression, addiction and obsessive-compulsive disorder, or OCD.
For Presley, the psilocybin experience caused his unhelpful rumination to cease. It knocked the critical, domineering voice in his head off-line. He glimpsed a level of self-acceptance and a sense of agency in his own life that he did not know was possible.
Charles Raison, a psychiatrist from the University of Wisconsin-Madison who specializes in depression, explains such experiences in Freudian terms. With the ego knocked offline, Freud's unconscious is given free rein to express itself, often revealing inner truths and deep insights that those taking the drugs might normally be blind to.
"The idea psychedelics liberate some of these powerfully valent, deeper emotional areas of the brain"the limbic areas involved in memory and emotion"to have their say is consistent with what people are reporting," says Raison, who also serves as director of clinical and translational research for Usona Institute, a nonprofit that is leading a clinical trial of psilocybin.
"They are often overcome by these really, really powerful emotions that are surprising, as if they're coming from the outside but yet seem completely credible and utterly believable. These areas are liberated and get their day in court."
None of this, however, explains perhaps the most enduring mystery of these drugs"what Raison calls "the holy grail," and others have referred to as the "black box" or the "hand wave" in our current scientific understanding.
Many brain disorders are defined by a "narrowed mental and behavioral repertoire" that confines those who suffer from them to "suboptimal patterns" they cannot break out of," says Matthew Johnson, a professor of psychiatry and behavioral sciences at Johns Hopkins and one of the coauthors of the depression study Aaron Presley participated in.
These "suboptimal patterns" manifest as behaviors, such as ruminative thinking and a reflexive expectation that things will go badly, and they also manifest physically in abnormal brain activity.
Many mental health disorders are characterized by aberrant brain activity, in which populations of specialized neurons, known as circuits, get stuck in rigid communication patterns and lose the ability to communicate effectively with other brain circuits. The brain loses the flexibility and the nimbleness that would allow it to respond to and interpret new situations and react accordingly. We become sick."
lots more about the way they think it werks at the link