Johns Hopkins Researchers Find Psychedelics Reopen The Social Reward Learning Period

Results from a recent study led by Johns Hopkins University scientists show evidence of psychedelics’ potential to reopen “critical periods” in mammals’ brains, and consequently, their ability to treat several debilitating conditions that current studies, more focused on PTSD, addiction and depression, do not address deafness, among others.

Published in the journal Nature on June 14, the researchers say the findings “provide a new explanation for how psychedelic drugs work,” concerning the molecular mechanisms impacted by them. Though preclinical, outcomes might well apply to humans.

JHU’s article defines "critical periods" in mammals as times when they are “more sensitive to signals from their surroundings that can influence periods of brain development,” performing functions such as helping birds learn to sing and humans learn a new language, relearn motor skills after a stroke, and establish dominance in one eye over the other.

The study's PI and associate professor of neuroscience at the university’s School of Medicine Gül Dölen says that after this “window of time” when the mammals’ brains are “far more susceptible and open to learning from the environment” closes, what remains is a state in which the brain becomes “much less open to new learning.”

The new study, in mice, shows that the psychedelics assessed -ibogaine, ketamine, LSD, MDMA and psilocybin - have in common the ability to reopen these periods, though the duration of each opening differs -ranging from two days to four weeks with a single dose.

The behavioral test sought to understand “how easily adult male mice learn from their social environment,” for which the researchers trained the animals to associate an environment linked with social interaction, and another one connected with being by themselves.

By comparing the time spent in each environment after the psychedelic’s administration, the team assessed whether the critical period opened in the adult mice, enabling them to learn the value of a social environment -a behavior usually learned as juveniles.

Results showed a single dose of ketamine opened the critical period of social reward learning for 48 hours; psilocybin and MDMA did so for two weeks; LSD for three and ibogaine for four weeks. 

According to the researchers, these findings in mice seem to roughly parallel the average length of time people self-report the acute effects of each psychedelic, which Dölen says hints another clue “in that the duration of psychedelic drugs’ acute effects may be the reason why each drug may have longer or shorter effects on opening the critical period.”

But more importantly, she says this open state “may be an opportunity for a post-treatment integration period to maintain the learning state,” and advises clinicians to “consider the time period after a psychedelic drug dose as a time to heal and learn, much like we do for open heart surgery.”

Photo courtesy of Rama on Wikimedia Commons.