What is Psilocybin?

One of the brightest sparks of scientific interest in recent years has been the renewed obsession with the kingdom of mushrooms. Though ritualistic psychoactive mushroom use has been traced back more than 3000 years to regions of Mexico, it was only in the 1960s that Western science started to pay serious attention. The scientists of that decade quickly fell to experimenting with mushrooms to treat an assortment of mental disorders, and their enthusiasm caught fire, igniting the collective imagination of the public. The craze was short-lived, however. In the 1970s, the psychoactive chemical found within mushrooms, known as psilocybin, was declared illegal and all human experiments were discontinued.

Psilocybin mania subsided over the next few decades. But in recent years it has reemerged, and it now seems set to remain a part of public consciousness. In fact, it's currently considered safe enough to be one of the most commonly used psychedelics in human studies. So what exactly is it, and what can it do?

Psilocybin is a chemical compound naturally occurring in many different families of mushrooms. In its pure form it's a white crystalline powder that looks much like salt or sugar.

Once you're ready for a 'trip' and ingest it, psilocybin is absorbed by the walls of your gut and quickly broken down into an alternate form called psilocin. Psilocin is actually the substance primarily responsible for the intense subjective effects a person feels, which normally peak about 90 minutes after the dose is swallowed. Though it floods every tissue in your body, psilocin's most important target is your brain. After three hours most of it will leave your body through your urine, and 24 hours after ingestion your system will be completely clean.

Within your brain, psilocin has a wide reach. The shape and physical qualities it has evolved allow it to fit into many different brain receptors. The most important of these receptors is one called 5HT2A. Despite its mundane name, this might be the most mysterious receptor the brain has, because it is also the target of other potent psychedelic drugs, like LSD, mescaline, and MDMA (commonly known as ecstasy).

The 5HT2A is naturally intended for a well-investigated chemical substance that also figures in the popular imagination - serotonin. And while you might think this would make the manner in which it functions straightforward to understand, nothing could be further from the truth. This is because serotonin is partially responsible for many different processes the brain makes the body engage in, among them sleep, fluctuations of blood pressure, and mood regulation. Why hallucinations should come about when psilocin attaches to a receptor involved in the pretty mundane tasks the body must engage in daily remains rather unclear.

Several compelling hypotheses do exist, however. For example, it may be the case that through its binding activity, psilocin creates an electrical environment inside of the brain which strengthens the neural connections dictating how you sense the world. At the same time, it may inhibit those connections that are responsible for your interpretation of sensory signals, and their transduction into a coherent picture of the world. In this scenario, psilocin would disrupt the reliable, steady circuitry your brain has forged over years of receiving input from your senses, giving you the ability to sense anew, in a way that is free of the expectations accumulated by your past experiences. As a result, you're plunged into a weird state of sensory rebirth.

This notion is very speculative, but it does a good job of breathing life into that well-worn phrase frequently used with respect to psychedelics: the 'altered state of consciousness.' Perhaps the psilocin trip is one during which the shackles of the Self, which the brain has meticulously worked to construct since even before your first breath, are temporarily thrown off. Your 5 senses can fully envelop all the aspects fed them by their environmental stimuli, presenting you for a brief time a richer world than the one necessity has worked to pare down into nothing more than its barest elements, those most useful for daily survival. Consciousness is indeed 'altered' - it appears to be continuous with the external world.

Whatever the truth of the matter is, mushroom-derived psychoactive compounds like psilocybin are here to stay. Their effectivity in the treatment of addictions and other mental disorders shows great promise. In fact, there might come a time when we come to forget what life was like without them.

References

• Tylš, F., Páleníček, T. & Horáček, J. Psilocybin – Summary of Knowledge and New Perspectives. European Neuropsychopharmacology 24, 342–356 (2014).