Mouse Study Splits Psilocybin's Brain Rewiring From Its Trip-Like Effects

Scientists at the University of California, Santa Cruz, report that they separated two effects of psilocybin in mice: the boost it gives to connections between brain cells and the trip-like response. The work was published in Nature Neuroscience, according to ScienceAlert.

Psilocybin, the psychedelic compound in "magic mushrooms," is being studied as a possible treatment for depression and post-traumatic stress disorder. Researchers would like to keep its potential benefits while leaving out the hallucinations. The new findings suggest that may be possible, but the experiments were done only in mice, not people.

What the researchers did in the mice

The team gave psilocybin to groups of mice and examined dendritic spines, the small connection points on nerve cells that let them communicate. According to ScienceAlert, the compound increased spine volumes and sped up spine development in less than 24 hours.

The team then altered the brain cells that respond to psilocybin. By genetically reconfiguring the "docking stations" on those cells, they kept one reaction and removed the other. This pointed to two separate pathways, one tied to plasticity (the brain's ability to adapt and rewire) and one tied to hallucination-like responses. In the mice, those responses were measured by proxy through head twitches.

Different effects in stressed and healthy animals

The results differed depending on the animals' condition. In mice put under stress, which is a rough approximation of depression in people, new spine formation increased even more, and the loss of existing connections was stopped. In healthy, unstressed mice, psilocybin sped up both the creation of new spines and the clearing away of old ones.

Molecular biologist Yi Zuo said the findings challenge the prevailing view that psilocybin simply increases neural connectivity, and suggest its effects depend on the brain's underlying condition. Neuroscientist Jacob Baker said the newly formed connections can integrate into existing circuitry and persist over time, leaving a lasting structural trace.

What researchers say and what remains unproven

Zuo called the work a major advance in understanding how psilocybin reshapes neural circuits. He said treatments built on this idea could deliver fast and lasting antidepressant benefits without hallucinogenic side effects, making them safer, more scalable and accessible to more patients.

ScienceAlert's own framing is more cautious. It noted that the work is at an early stage, that mouse findings need to be translated to people, and that it was previously unclear whether psilocybin's neuroplasticity benefits depended on its psychedelic effects. The study strongly suggests they do not, the outlet reported. Head twitches are also only a stand-in for a trip, since researchers cannot ask mice what they experienced.

Why it matters for people considering psychedelic therapy

Nothing here changes what treatments are available today. No drug based on this approach exists, and the study did not test people. The practical significance is that it gives drug developers a possible target: a compound that acts on the plasticity pathway while ignoring the hallucination pathway.

If that proves workable in humans, such a drug might offer some of psilocybin's effects without the intense experience that makes the current approach hard to deliver to many patients. That remains a hypothesis for now.

What comes next

ScienceAlert reported two possible next steps. One is isolating the specific brain cells responsible for the hallucination-like responses. The other is charting spine production against changes in the animals' mood, to understand more precisely how these changes affect the brain.

Around Prague, based on reporting by ScienceAlert