Magic mushrooms rewire the brain in a way scientists didn't expect
A surprising discovery reveals how psilocybin, the active compound in magic mushrooms, rapidly reshapes the brain by creating new neural connections and strengthening them. Researchers found that the drug behaves differently in healthy and chronically stressed mice, potentially helping repair brain circuits damaged by prolonged stress. Most intriguingly, they identified a way to trigger this brain rewiring without…
Key points
- Psilocybin spurred new dendritic spines in mice within 24 hours and helped them mature faster.
- Researchers separated the brain rewiring from a behavioral marker of psychedelic activity.
- Effects differed between healthy mice and mice exposed to chronic stress.
A study from the University of California, Santa Cruz, published October 15 in Nature Neuroscience, describes how psilocybin, the psychedelic compound in magic mushrooms, reorganizes connections between nerve cells in the brain. The researchers say the findings could eventually support treatments for mental health conditions that capture some of psilocybin's benefits without causing hallucinations.
Using two-photon microscopy, the team tracked individual connections on neurons in living mice over several weeks. Within 24 hours of psilocybin administration, they saw a substantial rise in newly forming dendritic spines, and a larger share than usual developed into mature, mushroom-shaped structures.
Healthy and stressed brains respond differently
In healthy mice, new connections formed but numbers drifted back toward previous levels over three weeks, partly as the brain removed some older connections. In mice exposed to an unpredictable mild stress model, psilocybin produced an especially strong increase in new spines and prevented the unusually high rate of connection loss linked to chronic stress.
Senior author Yi Zuo, a professor at UC Santa Cruz, said the results challenge the prevailing view that psilocybin simply increases neural connectivity and suggest its effects depend on the brain's underlying condition.
These findings challenge the prevailing view that psilocybin simply increases neural connectivity and suggest that its effects depend on the brain's underlying condition
— Yi Zuo
Separating rewiring from psychedelic effects
The team focused on serotonin 2A receptors on Layer 5 pyramidal neurons in the cerebral cortex. Restoring the receptors only in these neurons let psilocybin stimulate and stabilize new synapses, but the mice did not show the head twitch response used as an indicator of psychedelic activity in rodents. Removing the receptors blocked the structural growth while the head twitch response remained.
The authors say this points to a possible blueprint for non-hallucinogenic drug analogs, though they note the experiments were in mice and further research is needed to see whether the same mechanisms operate in humans.
