Hitting the brain’s reset button
If psilocybin or LSD can reduce DMN activity, it stands to reason that it might help those patients feel better. “People get locked into these very negative loops of thinking and feeling,” says Dr. Stephen Ross, an addiction psychiatrist at NYU who led the recent study on psilocybin. “It’s possible that by deactivating these kind of constrained circuits, you can disrupt it and reopen the person to another rhythm of thinking, perceiving, and behaving.”
More revealing may be brain imaging techniques like functional Magnetic Resonance Imaging (fMRI), which measures changes in blood flow to different parts of the brain. As viewed with fMRI, psychedelics clearly change patterns of brain activity. One striking shift is in the circuitry of the default mode network, or DMN, a group of brain regions that generally work in tandem when the mind is not focused on a particular task. It’s thought to include areas generally associated with higher-level thinking. The study of depression carries a hint of how quieting the DMN might lead to beneficial treatments. In a depressed person, the mind tends to race, flooded with negative thoughts. Indeed, brain-imaging studies suggest that the default-mode network is overactive in people who are clinically depressed.