Enhanced visual contrast suppression during peak psilocybin effects: Psychophysical results from a pilot randomized...

Area of Science:

• Neuroscience
• Psychology
• Psychiatry

Background:

• Surround suppression is a visual perception phenomenon where a center stimulus's contrast decreases with a higher-contrast surround.
• The neuromodulatory mechanisms underlying surround suppression are not fully understood.
• Psilocybin, a psychedelic, profoundly impacts visual perception.

Purpose of the Study:

• To investigate the effect of psilocybin on surround suppression during its peak effects.
• To explore the relationship between subjective psychedelic experiences and surround suppression magnitude.

Main Methods:

• A contrast-matching task was employed to measure surround suppression.
• Participants (n=6) received 25 mg psilocybin or a placebo (niacin).
• Harms data were collected, with no serious adverse events reported.

Main Results:

• Psilocybin administration led to significantly stronger reported surround suppression compared to placebo.
• The intensity of subjective psychedelic visuals correlated positively with the magnitude of surround suppression.
• No serious adverse events were reported.

Conclusions:

• Psilocybin alters visual surround suppression, potentially by enhancing it.
• Findings suggest a link between psilocybin's visual effects and surround suppression.
• Altered surround suppression may be relevant to visual disturbances in major depressive disorder and schizophrenia.