The field of psychedelic medicines is exciting. It holds the promise of changing psychiatry and psychiatric medicines forever. Psychedelics may be the best treatments for conditions like PTSD, depression, and substance abuse disorders. However, trying to get your head around how psychedelics work and some of the underlying concepts can be difficult. One such concept is called the default mode network. This is a set of connected parts of the human brain that may be integral in how psychedelics function.
Default Mode Network
Default mode network is a neuroscience term. Other names include default network, default state network, and a real mouthful, the medial frontoparietal network or M-FPN. This last term describes the physical parts of the default mode network in the brain. The parts of the network include the precuneus and angular gyrus, the posterior cingulate cortex, and the dorsal medial prefrontal cortex. This entire area becomes active together when people are at rest, wakeful and not thinking of the outside world such as when their mind is wandering or daydreaming. This area also becomes active as a person is planning for the future, remembering past events, thinking about themselves or thinking about others.
When a person is actively involved in a task in the world this area is not active. It does, however, turn on when the person is engaged in a conceptual or cognitive task or goal-oriented internal thinking. Prior research indicates that the default mode network is disrupted in Alzheimer’s disease, chronic pain, post-traumatic stress disorder (PTSD), schizophrenia, major depressive disorder (MDD), as well as with individuals who fall within the autism spectrum of disorders and attention deficit disorder (ADHD).
What Does Default Mode Mean?
Many years ago neuroscientists believed that the brain was essentially turned on during activity and thinking and off when a person was resting. However, EEGs or electroencephalograms show resting brain activity. Measurements of brain metabolism by PET scans show that the brain uses up calories in its “resting” state and only increases by about five percent when performing specific activities.
Default Mode Network As the Neurobiological Bases of the Self
Years of research have shown that the default mode network turns on and becomes active at times when self-related activities are going on in the brain such as the thinking about the following.
- Facts about oneself, memories of events relating to oneself
- Descriptions and traits referring to oneself
- Reflections on a person’s own emotional state
- Thinking about what others may be thinking or what they may or may not know
- Understanding the emotions of others and/or empathizing with their feelings
- Deciding about actions and if their results are just or not just
- Evaluating whether social concepts are good or bad
- Thinking about the social characteristics and/or status of a group
- Remembering the past and/or thinking about the future including detailed memories of specific events, remembering a narrative and understanding it, and consolidating traces of recently acquired memory
As one can see, the default mode network is not “turned off” when a person is not engaged in a task that others can see!
Psychedelic Medicines and the Default Mode Network
Researchers are interested in the connection between the default mode network and psychedelics because of two things. The default mode network shows changes or disruptions in people with conditions like PTSD and major depressive disorder. And psychedelics directly affect and, to a degree, reset the default mode network. The effect or setting of the default mode network happens in people who are given psychedelics as adjunctive therapy when receiving coaching or psychotherapy for treatment of depression, PTSD, substance abuse disorders and other conditions.
The Physical Basis of Thoughts, Anxiety, and Fears
Nobody completely understands how the human brain works or how to reliably fix things when they go wrong. But researchers are using modern tools like advanced brain scans to improve our understanding. In this regard, those who are looking to use psychedelics for difficult to treat conditions like PTSD and major depression have identified changes in the default mode network and those changes correlate with clinical improvement. It will not be necessary to completely understand how we think and feel and the parts of the brain that are responsible. But every bit of understanding contributes to advancing treatment with psychedelic medicines and other approaches. Understanding more about the default mode network is part of working on this puzzle.