Study led by the University of Coimbra identifies mechanisms of visual distortion induced by psychedelics
Scientists have uncovered a mechanism that alters the resolution of both central and peripheral vision, explaining visual phenomena such as tunnel vision. This finding marks another significant advance in understanding the effects of psychedelics on humans.
A new study led by the University of Coimbra (UC) reveals a mechanism that may help explain some of the phenomena associated with the visual effects of psychedelics. Specifically, the study identifies a mechanism that alters the resolution of both central and peripheral vision, shedding light on visual phenomena like tunnel vision (the loss of peripheral vision). This research represents a significant advancement in understanding the effects of psychedelics on humans, particularly their impact on the visual field.
In the scientific article Rapid effects of tryptamine psychedelics on perceptual distortions and early visual cortical population receptive fields - recently published in NeuroImage, one of the most prestigious journals in the field of brain imaging - the research team, led by Miguel Castelo-Branco, Professor at the Faculty of Medicine of the University of Coimbra (FMUC) and Scientific Coordinator of the Centre for Biomedical Imaging and Translational Research (CIBIT) at the UC Institute of Nuclear Sciences Applied to Health (ICNAS), studied the effects of inhaled dimethyltryptamine (DMT) on several participants.
DMT is a natural psychedelic that simulates the effects of serotonin, a neurotransmitter in the brain that regulates mood, sensory sensitivity, sleep, appetite, sexuality, stress response, memory, and other cognitive functions.
In the altered perception identified by the research team, ‘central vision remains sharp while peripheral vision becomes blurred’, explains Miguel Castelo-Branco. ‘It's as if people under the influence of this psychedelic have larger pixels in their visual brain, which reduces the resolution and leads to altered perception of visual objects, especially in the periphery.’
The research team used functional magnetic resonance imaging, a technique for studying brain activity and functional changes in the regions that process visual information. This allowed the researchers to 'map changes in the response properties of brain regions that respond to visual stimuli,' says the neuroscientist.
'Identifying a relationship between changes in visual maps and surprising perceptual experiences, as in our study, opens the door to linking precise changes in sensory maps with phenomena such as certain forms of hallucinations, including changes in perceived visual space,' says Miguel Castelo-Branco.
This novel study in the Portuguese context, whose first author is Marta Lapo Pais, a PhD student and researcher at ICNAS, is part of a research project led by Miguel Castelo-Branco. The project aims to 'study the mechanisms underlying psychedelics, the phenomenology of perception, the mental states involved and their potential therapeutic effects,' explains the neuroscientist.
‘With this research, we hope to open new avenues for understanding the effects of psychedelics on the affective, spiritual and cognitive dimensions of the human being, the brain responses they induce and their possible therapeutic implications,' emphasises the UC professor.
Researchers who have also contributed to this article: Marta Teixeira (CIBIT and ICNAS), Carla Soares (CIBIT and ICNAS), Gisela Lima (ICNAS, FMUC and Maastricht University), Célia Cabral (CiBB, iCBR, FMUC and CFE) and Patrícia Rijo (Research Institute for Medicines, University of Lisbon and Research Center for Biosciences & Health Technologies, Lusófona University).
The scientific article is available here.