There is still much unknown about Psilocybin’s mechanism on the brain. The subjective experience when taking psychedelics can range massively, without there being any concrete predictors or biomarkers that can indicate what the subjective experience may look like.

In this study researchers took EEG measures on participants both during resting state and again 60 minutes after administration. They were assessed for 5 minutes with eyes open and for 5 minutes with eyes closed. Lighting and ambient music was used to create pleasant scenes. Participants also filled in the ASC-5 questionnaire, which quantifies the subjective effects across dimensions of: Boundlessness, Dreadful Ego Dissolution, Visual Restructuralization, Auditory Alterations and Vigilance Reduction.

When the five ASC 5 dimensions were broken down, each showed a distinct neural fingerprint. Every ASC-5 item correlated positively with widespread power changes, with items such as Oceanic Boundlessness being tightly linked to increased gamma power particularly in limbic areas, and Anxious Ego Dissolution was more associated with occipital activity.

Psilocybin also reshaped the Default Mode Network (DMN) Compared with placebo, slow frequency (theta, alpha) power dropped across the DMN while fast frequency (beta, gamma1, gamma2) power rose, especially in frontal, temporal and limbic zones. Connectivity analysis revealed a marked increase in long range links within the DMN at these high frequency bands, whereas low frequency connections weakened. The net effect was a DMN that became more globally synchronized at beta gamma ranges, reflecting the network’s heightened integration during the psychedelic state.

Additionally. resting state EEG proved to be a surprisingly strong predictor of how intensely participants rated their psychedelic trip. The researchers first examined baseline power across theta, alpha, beta and gamma bands and linked those values to later ASC 5 scores, showing that higher pre drug activity in fast (beta/gamma) frequencies foretold stronger subjective effects1. Notably, frontal and limbic regions that displayed elevated baseline beta and most gamma power were tied to a more intense psychedelic experience.

Overall, this study provides exciting initial biomarkers of psychedelic experiences, which has the potential for improved and tailored clinical intervention.

Psilocybin traditionally has a bioavailability of around 52%, as well as a metabolic elimination rate which can vary. This is a problem when medicating with psilocybin, as it can lead to inconsistencies in what the appropriate dose would be.

An alternative formulation of psilocybin, (L-130), has been found with a bioavailability of 99%. Here, researchers use a rat model to demonstrate that it is not only safe but also showed expected improvements in anxiety

Rats were split into 5 groups, one acting as an unstressed control, with the remaining four receiving either saline or L-130 at daily and weekly intervals. Non-control rats were exposed to varying mild stressors over 28 days to induce anxiety-like symptoms, before undergoing blood work and behavioural assessments.

Safety results were encouraging, with no notable differences in blood-related markers, weight, or feed consumption across groups. Daily L-130 treatment significantly reduced cortisol levels relative to stressed controls, approaching those of unstressed animals.

Behaviourally, this group outperformed controls across all three anxiety tasks. Weekly dosing showed limited and inconsistent effects across measures, and head twitch responses indicating hallucinogenic activity were low and confined to the daily group. No tolerance developed over the 28-day period.

These findings suggest L-130 as a strong candidate for further pharmacological development. Its tighter dosage control, enabled by near-complete bioavailability, could allow for at home treatments while minimising the risk of unwanted hallucinogenic effects — making structured, precise clinical application considerably more achievable than with traditional psilocybin

The claustrum is a small subcortical structure sitting between the insular cortex and striatum, densely packed with serotonin 5-HT2A receptors. Despite long being theorised as a hub for sensory integration and consciousness, how psychedelics actually alter its neurochemistry had never been directly examined.

This study used in vivo microdialysis in freely moving rats to measure how psilocin and the synthetic compound 25I-NBOMe altered extracellular neurotransmitter levels directly within the claustrum. Samples were collected over two hours, with all changes expressed relative to baseline. A wet dog shake test was also used to measure hallucinogenic activity.

Both compounds showed elevated 5-HT (serotonin) levels, but 25I-NBOMe produced the strongest cumulative response. Notably, the higher psilocin dose resulted in lower 5-HT release than the lower dose, an effect the authors attribute to dose-dependent recruitment of inhibitory 5-HT1A receptors, which appear to dampen serotonergic output as a form of negative feedback. This self-limiting mechanism is absent with 25I-NBOMe, whose selective and high-affinity 5-HT2A agonism drives prolonged, unmodulated serotonergic activation.

The glutamate findings further distinguished the two compounds. 25I-NBOMe induced a more pronounced and sustained elevation in extracellular glutamate, whereas psilocin's response appeared to reach a ceiling effect at higher doses, again pointing toward inhibitory counter-regulation via 5-HT1A engagement. The authors highlight the resulting GLU/GABA ratio as a critical marker with psilocin at lower doses preserving excitatory-inhibitory balance, and 25I-NBOMe shifting the claustrum decisively toward excitatory dominance.

Taken together, these findings position the claustrum as a neurochemical convergence point as an active integrator of multiple transmitter systems simultaneously, as opposed to a simple sensory relay station.

It is largely established that psychedelics can have beneficial therapeutic effects across various psychiatric conditions, including major depressive disorder. Despite this, the exact mechanism that underpin this effect is not fully understood.

Rats were first trained in a reward learning essay. Here they were given various combinations of ceramic bowls which contained different amounts of a food reward (0, 1, or 2 pellets). This was done in a sequence which trained the rats to recognise how much reward was associated with each bowl creating a positive choice bias. This meant rats were more likely to choose the bowl that gave the most reward.

Rats were then split into 3 groups, with 2 groups being treated daily (for 14 days) with interferon alpha to induce a depression like phenotype. The other group remained as a control.

After 14 days, rats were re-tested in their reward learning environment. In rats where a depression phenotype was induced, a blunting of their positive choice bias was shown. This meant that while control rats maintained a preference for higher reward options, these rats were indifferent to higher or lower reward options.

Within the 2 groups of depressed rats, one group received psilocybin treatment, whereas the other group was given a salient solution to act as a control. In the psilocybin treated group, a significant reversal of the learning impairment was shown by 24 hours and persisted for up to 7 days.

Here, researchers demonstrate that psilocybin is able to rapidly restore depression induced deficits in reward learning. They then go on to suggest that this reversal is a potential mechanism by which psilocybin exerts its antidepressant effect. Specifically they reference the nucleus accumbens as a potential site where these changes may take place, as this is an area already implied in reward learning.

Researchers demonstrate Benzodiazepines negate long term antidepressant effect in rat models

Researchers gave rats either Saline (S), Saline and Psilocybin (S/P), or Psilocybin with prior administration of Lorazepam (L/P), a benzodiazepine that is often psychiatrically prescribed to manage anxiousness.

The antidepressant effects of each condition was measured via the forced swim test , a common measure of antidepressant effect in rodent models. This was done at 3 and 14 weeks, after administration.

At 3 weeks, both S/P and L/P groups were significantly more active in the forced swim test than the Saline control, suggesting an antidepressant effect. At week 14 the S/P group maintained significantly greater movement, demonstrating a long-term antidepressant effect which was expected. The L/P group showed reduced activity at week 14, in line with the Saline control group.

While this finding suggests the long term antidepressant effect of Psilocybin is mitigated by Lorazepam, researchers note that this is merely an exploratory study. The lack of positive control, to measure Lorazepam’s effect on the forced swim test, as well as a lack of locomotor assessments means there should be caution surrounding these findings.

Despite this, these findings still have interesting implications for treatment protocols involving benzodiazepines, as well as give further insight to the neural mechanisms that underlie psilocybin’s antidepressant effect