Psychedelics and Critical Periods


Scientists have been exploring methods to reopen “critical periods” in the brain, allowing mammals to be more receptive to environmental signals that influence brain development. Recent research on mice indicates that psychedelic drugs have the ability to reopen these critical periods, albeit with varying durations. This article examines the Psychedelics and Critical Periods and the implications of these findings for treating a wider range of conditions and provides insights into the molecular mechanisms underlying the effects of psychedelics.

Significance of Critical Periods:

Critical periods are pivotal for various learning processes, such as birds learning to sing or humans acquiring new languages and regaining motor skills after a stroke. During these periods, the brain exhibits heightened sensitivity to environmental stimuli, facilitating efficient learning and adaptation.

Exploring the Impact of Psychedelic Drugs:

Gül Dölen, an associate professor of neuroscience at Johns Hopkins University School of Medicine, and her team have investigated how psychedelic drugs reopen critical periods. Initially focusing on MDMA, a drug known for its prosocial effects, they discovered its ability to open critical periods in mice. Surprisingly, subsequent research revealed that other psychedelics without prosocial properties can also reopen critical periods.

Examination of Five Psychedelic Drugs:

The research team examined the reopening potential of five psychedelic drugs: ibogaine, ketamine, LSD, MDMA, and psilocybin. By conducting behavioral tests on adult male mice, they evaluated the mice’s capacity to learn from their social environment after administering these drugs. The duration of the critical period varied among the drugs, ranging from 48 hours for ketamine to four weeks for ibogaine.

Correlation Between Drug Effects and Critical Period Duration:

The researchers observed a correlation between the duration of the acute effects of each psychedelic drug and the length of time the critical period remained open in mice. This suggests that the acute effects of the drugs may influence the duration of the critical period reopening.

Molecular Mechanisms Underlying Critical Period Reopening:

To comprehend the molecular mechanisms involved, the team examined the serotonin sense organ and ribonucleic backbreaker (RNA) verbal expression in mouse brain cells. They discovered that LSD and psilocin utilize the serotonin receptor to reopen the critical period, while MDMA, ibogaine, and ketamine do not. Furthermore, the researchers identified gene expression differences related to the extracellular matrix, which plays a role in social learning behaviors responsive to rewards.


The study emphasizes the potential of psychedelic drugs to reopen critical periods, offering opportunities for enhanced learning and adaptation. The findings suggest broader applications for these drugs beyond the currently studied conditions like depression, addiction, and post-traumatic stress disorder, including stroke recovery and hearing impairment. Understanding the molecular mechanisms involved opens avenues for further research and potential therapeutic advancements.

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