Psychedelics and the Brain – Reopening the Window of Learning
Psychedelics are a class of compounds that act on the serotonergic system, altering consciousness. This group includes lysergic acid diethylamide (LSD), psilocybin (magic mushrooms), 3,4-methylenedioxymethamphetamine (MDMA or ecstasy), and dimethyltryptamine (DMT). Each of these substances affects the brain in slightly different ways.
In recent years, numerous clinical studies have shown that psychedelic compounds — when administered in medically controlled and supportive environments — can improve the condition of people suffering from mood disorders such as major depression, anxiety disorders, or PTSD.
Some scientists are now investigating whether these powerful substances might also help heal physical brain injuries and other conditions caused by disrupted neural connections. This could have significant implications for treating stroke, traumatic brain injury, and neurodegenerative diseases such as Alzheimer’s and Parkinson’s.
Expanding the Brain’s Learning Capacity – Overcoming Critical Periods
Human brains develop in a way that certain skills can only be easily acquired during specific stages of development, known as critical periods. For example, the first six years of life are essential for language development. If a child does not experience language exposure during this period, they will likely never develop speech — even with a healthy vocal apparatus. This occurs because specific brain areas responsible for speech fail to develop properly once the window closes.
Recent research suggests that psychedelics may reopen these critical learning periods in adult animals. Scientists at Johns Hopkins University in the United States discovered that adult rodents given psychedelics were able to learn certain social behaviors that normally develop only during youth.
The researchers trained socially undeveloped mice to associate one environment with isolation and another with social interaction. Initially, the mice preferred isolation. However, after a single dose of LSD, psilocybin, or another psychedelic, the animals were able to choose freely — and most began preferring the social environment.
In other words, they overcame the critical period for social learning, acquiring new social behaviors later in life than science previously thought possible.
“This likely happens because psychedelics remain bound to serotonin receptors for an extended time, overwhelming neurons and triggering a complete reset — much like rebooting a frozen computer. The resulting cascade of cellular events resets the brain to an earlier developmental state,” explains Dr. Gül Dölen, author of the study.
Could This Help in Brain Injury Rehabilitation?
This ability could have important implications for treating strokes and traumatic brain injuries.
When a person suffers a neurological injury and certain neurons — for example, those responsible for speech — are damaged, the brain tries to reroute pathways to relearn the skill. It’s said that a new “critical period” temporarily opens for relearning speech or motor skills after such an event, allowing for partial recovery. However, this window typically closes after about six months, making further progress difficult.
Psychedelics may have the potential to reopen or extend this learning window, offering hope for people with neurological disorders or brain injuries.
Reopening the brain’s critical learning period also indirectly supports the importance of psychedelic integration therapy — the psychotherapeutic process following a psychedelic experience. During this time, the brain is more receptive, and integration work can help establish new neural pathways and lasting psychological change.
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References:
Nardou R., Sawyer E., Song Y.J., Wilkinson M., Padovan-Hernandez Y., de Deus J.L., Wright N., Lama C., Faltin S., Goff L.A., Stein-O’Brien G.L., & Dölen G. (2023). Psychedelics reopen the critical period for social reward learning. Nature. DOI: [10.1038/s41586-023-06204-3]
(Based on the article by Meryl Davids Landau, National Geographic Ciencia, August 23, 2023)