Psychedelic Drugs and the Reopening of Critical Periods: Implications for Neuroplasticity

Table of Contents

1 Increased sensitivity of neurons
2 Clinical significance
3 Conclusion
- - 3.0.1 References

Psychedelics or hallucinogens are a class of psychoactive drugs that affect emotions, perception, and cognitive processes. Psychedelics alter a person’s thoughts, sense of time, and emotions by affecting all of the senses. Additionally, a person may have hallucinations, in which case they hear voices or see unreal objects. Since their origin, psychedelics have been revered for their mystical and spiritual qualities by several civilizations. Interestingly, despite the fact that researchers are still unsure of how exactly psychedelic drugs work, many mental health conditions can improve from their use.

Psilocybin Mushrooms. Image Courtesy of Arp

Increased sensitivity of neurons

Ecstasy, ketamine, and psilocybin are just a few of the psychoactive substances that are known to have mind-altering effects, sometimes involving hallucinations. Some studies have shown that there is a potential mood benefit of psychedelics. However, each substance affects a different biochemical route in the brain acting over a short time, leaving scientists perplexed as to why so many of these medications have the long-term potential to treat addiction, depression, and other difficult-to-treat illnesses.

Some neuroscientists at John Hopkins University, Baltimore carried out a study on mice to assess how psychedelics affect their social behavior. Mice can learn to correlate social interaction with pleasurable emotions, but only while they are adolescents. This “critical period” fades away as they grow into adults. The mice were trained to connect one of the rooms in their enclosure with company, and another with solitude. This helped determine whether the drug changed the critical period by looking at how the psychedelics altered the rodents’ room preferences.

It was discovered in previous studies that administering MDMA to adult mice in the presence of other adult mice re-established the critical period, increasing the likelihood of the treated animals sleeping in the social room compared to the control mice. This was expected because MDMA is well known for encouraging human and animal connection. In the current study, MDMA was administered to adult mice, or one of four hallucinogenic substances—LSD, ibogaine, psilocybin, or ketamine—that aren’t known to foster social behavior. The social room was more frequently chosen by mice who had taken any of the psychedelic drugs than by mice who hadn’t, indicating that each of the medications had the potential to reopen the critical period.

Furthermore, mice fell unconscious when given excess ketamine. Each substance had a distinct duration of opening the critical period, ranging from a week for ketamine to over four weeks for ibogaine. They also discovered that the oxytocin has increased the sensitivity of neurons in particular brain regions of the mice. They are more likely to reorganize and generate new connections in this state, which would imply that the neurons were responding.

Clinical significance

Currently, testing is done to ascertain whether additional important periods, such as those for the motor system, can be reopened by psychedelic substances. Reopening it might extend the time during which stroke victims might benefit from physical treatment.

Conclusion

The discovery offers optimism that critical moments are not irreversible and can be reopened. A very precise molecular knowledge of psychedelic drugs may hold the key to unlocking brain plasticity.