The mind-altering effects of psychedelics like MDMA, ketamine, and psilocybin are well-known, but scientists have been puzzled by their ability to provide long-term relief from conditions like depression and addiction. To uncover the reasons behind this, a team of researchers led by Gül Dölen from Johns Hopkins University studied how psychedelics impact social behavior in mice.
The researchers focused on the critical period of adolescent mice when they associate socializing with positive emotions. By training the mice to associate different rooms with social interaction or solitude, they observed the effects of psychedelics on the mice’s room preferences. The team found that giving adult mice MDMA in the presence of other mice reopened the critical period, leading to a greater likelihood of choosing the social room.
In their new study, the researchers administered either MDMA or four other psychedelic drugs (ibogaine, LSD, ketamine, and psilocybin) to adult mice. They discovered that mice receiving any of the psychedelic drugs were more inclined to choose the social room, indicating that each drug could reopen the critical period. However, when mice were given a high dose of ketamine, rendering them unconscious and unaware of their companions, they did not exhibit a preference for the social room. This suggests that the drugs only reopen the critical period when taken in a social context.
Examining the mice’s brains, the researchers found increased sensitivity to oxytocin, the “love hormone,” in specific brain regions. They believe that the drugs induce a state of metaplasticity in neurons, making them more responsive to oxytocin and more likely to form new connections. The drugs also influenced the expression of genes involved in regulating a protein matrix on the neuron’s surface, potentially allowing the neurons to grow and establish new connections.
Gül Dölen suggests that psychedelics act as a master key, capable of unlocking various critical periods by inducing metaplasticity in neurons. The specific outcome depends on the context in which the drugs are taken. This study provides insight into the relationship between critical period opening and the altered state of consciousness induced by psychedelics.
Experts such as Takao Hensch from Harvard University see this research as groundbreaking in understanding the biological mechanisms of psychedelic drugs. They believe that gaining a comprehensive understanding of these drugs could potentially reopen brain plasticity and reverse critical periods. However, skeptics like David Olson from the University of California, Davis, caution that the drugs may simply alter physical connections between neurons instead of inducing metaplasticity. Currently, Gül Dölen is investigating whether psychedelic drugs can reopen other critical periods, such as those related to the motor system. If successful, this research could extend the benefits of physical therapy for stroke patients beyond the limited time frame currently available.
