Once maligned for their psychedelic properties, magic mushrooms are gaining increasing attention for their mind-altering potential as a therapy for a wide variety of mental health issues.
Yet surprisingly little is known about the various neurological effects of the mushroom’s psychoactive compound, psilocybin, making it difficult to predict how the drug might ultimately benefit the community as a medicine.
A study led by psychiatrist Joshua Siegel of the University of Washington School of Medicine tracked brain changes in seven healthy adults before, during, and after taking a high dose of psilocybin, identifying disruptions in connectivity that persisted for weeks in certain areas of the brain.
These findings fill gaps in our understanding of how psilocybin’s biochemical influence translates into large-scale behavioral changes that can help or hinder individuals with different psychological needs.
“Today we know a lot about the psychological effects and the molecular/cellular effects of psilocybin,” Siegel says.
“But we don’t know much about what’s happening at the level that connects the two – the level of functional brain networks.”
Magic mushrooms weave their spell by mimicking serotonin’s affinity for the 5-HT2A receptor. The subjective effects are well known, typically including euphoria associated with distortions in the perception of self, time, space, sound, and color.
Animal models confirm that brief activation of these receptors in regions where they are found in high density, such as the medial frontal lobe, triggers lasting effects by loosening hardwired pathways and promoting new connections.
It is this same “plasticity” of the nervous system that allows our brains to be adaptable, making psilocybin an attractive pharmaceutical for treating psychological disorders that stubbornly resist change.
It’s unclear, however, whether the same findings apply to humans. So Siegel and his team conducted functional magnetic resonance imaging scans on volunteers before they took a generous 25-milligram dose of psilocybin. Further scans were conducted immediately after the dose and again 21 days later.
For comparison, subjects also received a 40-milligram dose of methylphenidate, a stimulant, on separate occasions, and a similar series of tests were performed.
The scans clearly showed a significant disruption in the functional connectivity of the cerebral cortex after the psilocybin dose. Deeper in the brain, major changes were also observed in a group of regions that are more active when we are awake but not engaged in a task, known as the default mode network (DMN).
Based on previous studies involving rats, the researchers suspected that the widespread disruption resulted from populations of nerve cells that normally coordinate their activity becoming desynchronized, temporarily erasing the unique patterns that give rise to our sense of self.
“The brains of people taking psilocybin are more similar to each other than to those of people who don’t take it,” says neurologist and lead author Nico Dosenbach.
“Their individuality is temporarily destroyed. This confirms, at a neuroscientific level, what people say about losing their sense of self during a trip.”
Interestingly, giving the volunteers a simple auditory-visual matching task after their psilocybin dose while they were being scanned appeared to “anchor” their DMN, reducing the severity of the disruption.
Scans three weeks after psilocybin treatment showed that the cortex had largely returned to predose synchrony. Yet a region called the anterior hippocampus, which is involved in a range of cognitive processes involving perception and memory, continued to show persistent functional change.
Connecting what we know about psilocybin’s pharmacology to self-reported and cultural knowledge of its effects in a neurological setting could pave the way for treatments that alleviate depression or reduce post-traumatic stress, or serve as a way to caution against its use in situations where disruption could pose significant risks.
We may still be a long way from being able to visit our doctor for a dose of mushrooms that will help us get our minds back on track, but studies like this one bring us one step closer to understanding the fascinating relationship between our brains and this magical group of fungi.
This research was published in Nature.
News Source : www.sciencealert.com
Gn Health
