Study finds psychedelic drugs restart ‘critical period’ of social learning

Neuroscientists have long sought ways to restart the brain’s “critical period.” This critical period is when mammals become sensitive to signals from their surroundings that can affect brain development. Now, in a new study in mice, researchers at Johns Hopkins School of Medicine show that psychedelic drugs are related by a common ability to reopen such critical periods, but differ in how long the critical periods open. In other words, it was shown that the period during which the critical period opens is from 2 days to 4 weeks. Single dose.

Findings were published in the journal on June 14 NatureScientists offer new explanations for how psychedelic drugs work, and beyond the diseases currently researched on psychedelic drugs, such as depression, addiction and post-traumatic symptoms, to stroke and stroke. It suggests the potential to treat a wider range of conditions, such as hearing loss, he said. stress disorder. Scientists are also providing new insights into the molecular mechanisms affected by psychedelic substances.

Critical periods help birds learn songs, help humans learn new languages, relearn motor skills after a stroke, and perform functions such as giving one eye dominance over the other. proven to fulfill.

“There is a period when the mammalian brain is more sensitive and open to learning from the environment,” he says. Fertilizer for roses, Associate Professor of Neuroscience, Johns Hopkins University School of Medicine. “This window closes at some point, after which the brain becomes less open to new learning.”

Dalen’s team has studied how psychedelic drugs work by reopening these critical periods, building on the experience of the lab that studied social behavior. In 2019, her team found that MDMA, a hallucinogen that evokes affection and sociability, causes critical periods in mice.

At the time, Doren thought that MDMA’s prosocial properties would smooth the way to restarting the critical period, but her team in the current study also found that other psychedelic drugs without prosocial properties could also be critical. She said she was surprised to discover that her period could be restarted.

In this study, Doren’s team used ibogaine, ketamine, LSD, and MDMA, which have been shown in numerous studies to alter our normal perception of existence and enable a sense of discovery about ourselves and ourselves. , examined the possibility of restarting five psychedelic drugs, psilocybin. world.

The research team conducted a well-established behavioral test to understand how easily adult male mice learn from their social environment. They trained mice to develop associations between an environment associated with social interaction and another associated with being alone. By comparing the time spent in each environment after mice were given a hallucinogenic drug, the researchers found that a critical period opens up in adult mice, allowing them to learn the value of their social environment, which is usually when they were juveniles. I was able to confirm whether I could learn the behavior to do.

In ketamine-treated mice, the critical period for social reward learning remained open in mice for 48 h. For psilocybin, the open state lasted him two weeks. The critical period remained open for 2, 3, and 4 weeks in mice treated with MDMA, LSD, and ibogaine, respectively.

The researchers say the length of time the critical period was open in mice appears to be roughly comparable to the average length of time people self-report the acute effects of each psychedelic drug.

“This relationship gives us another clue that the duration of the acute effects of psychedelic drugs may be the reason why each drug has a longer or shorter impact on the onset of the critical period,” Dalen said. To tell.

“The open critical period could be an opportunity for the post-treatment consolidation period to maintain the learning state,” she added. “Often, after receiving a procedure or therapy, people return to a chaotic, hectic life and feel overwhelmed. And you might want to think of it as a learning time’ for open-heart surgery. ”

Scientists then investigated the effects of psychedelic drugs on molecular mechanisms. First, they looked at junctions known as receptors for the neurotransmitter serotonin in mouse brain cells. The researchers found that LSD and psilocybin use serotonin receptors to open the critical period, but MDMA, ibogaine, and ketamine do not use serotonin receptors.

To explore other molecular mechanisms, the researchers turned to ribonucleic acid (RNA), a cousin of DNA that tells which genes are expressed (making proteins) in mouse cells. The researchers found expression differences between 65 protein-producing genes during and after the onset of the critical period.

Approximately 20% of these genes control proteins involved in extracellular matrix maintenance or repair. The extracellular matrix is ​​a type of scaffold that envelops brain cells in the nucleus accumbens, a region associated with reward-responsive social learning behavior.