Psilocybin disrupts attention and higher information processing, but not automatic auditory detection

There is a scientific article that investigates how psilocybin influences different levels of auditory information processing in healthy volunteers.

In it, we discuss:

The researchers used psilocybin as a serotonergic model of psychosis to examine what happens to specific EEG signals that indicate attention and information processing. In doing so, they focused primarily on the P300 and mismatch negativity, also known as MMN. These measures are often used in research into schizophrenia and other conditions in which information processing is disrupted.

The real focus of this article lies on the distinction between automatic, pre-attentive processing and more conscious, attention-dependent processing. In a placebo-controlled, double-blind crossover study, 20 healthy participants received an oral dose of psilocybin of 0.26 mg/kg. Event-related potentials were measured during the peak effect and compared with placebo.

The results show that psilocybin caused distinct psychedelic and psychosis-like effects, while simultaneously significantly reducing the P300 amplitude. This points to disruption of higher cognitive processing and attention. The N100 amplitude also decreased, suggesting that even early perceptual processing was partially affected.

At the same time, mismatch negativity remained unchanged. According to the authors, this means that automatic, pre-attentive auditory anomaly detection was not clearly disrupted by psilocybin under these conditions. Thus, psilocybin appears to disrupt primarily higher and partly early perceptual processing, but not all levels of information processing simultaneously.

It also appeared that the decrease in P300 was associated with the intensity of the psychedelic state, which in turn was associated with the psilocin level in the blood. The disturbance of P300 therefore does not appear to be simply an isolated EEG effect, but is related to the strength of the substance's subjective and pharmacological effects.

It is important, however, that this research was conducted on healthy volunteers in an experimental setting. The article therefore does not show that psilocybin mimics schizophrenia, but rather that stimulation of serotonergic 5-HT2A/2C-related systems can demonstrably disrupt certain information processing processes.

In one sentence: this article shows that psilocybin primarily disrupts early sensory and higher cognitive processing, while automatic pre-attentive auditory processing remains largely intact.