Frontiers in Pharmacology
March 2, 2018
Link Swanson
185 citations
Psychedelic drugs produce acute effects on perception, emotion, cognition, and sense of self. This review traces theories of these effects over 125 years, from model psychoses, filtration, and psychoanalytic theories in the late 19th and early 20th centuries to modern frameworks like entropic brain theory, integrated information theory, and predictive processing. A common principle across theories is that psychedelics perturb brain processes that normally constrain neural systems central to perception, emotion, cognition, and self. Investigating these mechanisms offers a powerful way to develop and test unifying theories of brain function.
Journal of Vision
November 5, 2024
Sophia Jungers, Ranji Varghese, Link Swanson et al.
2 citations
A small experiment with six participants tested whether the psychedelic compound psilocybin alters surround suppression, a visual effect where a high-contrast background reduces the perceived contrast of a central object. After taking 25 mg of psilocybin, participants reported stronger surround suppression compared to placebo (100 mg niacin). The intensity of subjective psychedelic visuals correlated positively with the magnitude of surround suppression. No serious adverse events occurred. The findings suggest a link between serotonergic neuromodulation and visual contrast perception, and may relate to weakened surround suppression observed in major depressive disorder and schizophrenia.
January 11, 2024
Link Swanson, Sophia Jungers, Ranji Varghese et al.
1 citation
preprint
Surround suppression, a visual effect where a central stimulus appears less contrasty when placed inside a higher-contrast surround, is altered by the psychedelic compound psilocybin. In a small experiment with six participants, a 25 mg dose of psilocybin produced stronger surround suppression of perceived contrast compared to a placebo (100 mg niacin). The intensity of subjective psychedelic visuals correlated positively with the magnitude of surround suppression. This finding may be relevant to understanding visual effects of psilocybin and its therapeutic mechanisms, given that weakened surround suppression has been observed in major depressive disorder, for which psilocybin is considered a breakthrough therapy.