This theory building (2024) elucidates a new understanding of psychedelic modulation in the retinofugal pathway (between the eye and primary visual cortex). It suggests that disruptions in communication between cortical and subcortical regions, influenced by serotonin receptors, may lead to perceptual alterations and hallucinations. The study highlights the potential significance of the retinofugal pathway, particularly the role of amacrine cells, in shaping subjective psychedelic experiences, drawing parallels with rare medical conditions like Charles Bonnet syndrome.
Abstract of Visual hallucinations originating in the retinofugal pathway under clinical and psychedelic conditions
“Psychedelics like LSD (Lysergic acid diethylamide) and psilocybin are known to modulate perceptual modalities due to the activation of mostly serotonin receptors in specific cortical (e.g., visual cortex) and subcortical (e.g., thalamus) regions of the brain. In the visual domain, these psychedelic modulations often result in peculiar disturbances of viewed objects and light and sometimes even in hallucinations of non-existent environments, objects, and creatures. Although the underlying processes are poorly understood, research conducted over the past twenty years on the subjective experience of psychedelics details theories that attempt to explain these perceptual alterations due to a disruption of communication between cortical and subcortical regions. However, rare medical conditions in the visual system like Charles Bonnet syndrome that cause perceptual distortions may shed new light on the additional importance of the retinofugal pathway in psychedelic subjective experiences. Interneurons in the retina called amacrine cells could be the first site of visual psychedelic modulation and aid in disrupting the hierarchical structure of how humans perceive visual information. This paper presents an understanding of how the retinofugal pathway communicates and modulates visual information in psychedelic and clinical conditions. Therefore, we elucidate a new theory of psychedelic modulation in the retinofugal pathway.”
Authors: Zeus Tipado, Kim P. C. Kuypers, Bettina Sorger & Johannes G. Ramaekers
Summary of Visual hallucinations originating in the retinofugal pathway under clinical and psychedelic conditions
Introduction
Louis Lewin’s book “Phantastica” served as the world’s first categorization of various psychoactive substances. The first experimental study on the effects of psychedelics on visual hallucinations was led by Chicago-based scientists. They used electroretinography to record activity in the retina and visual cortex in forty-four cats and concluded that LSD did not induce hallucinations by virtue of an effect on the central nervous system.
We hypothesize that modulation of visual information after taking psychedelics already happens earlier in the visual pathway, through neuroreceptors embedded within amacrine cells that are known to be affected by psychedelics via direct or indirect action on dopamine, acetylcholine, GABA, opioid, and serotonin (5-HT) receptors.
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https://doi.org/10.1016/j.euroneuro.2024.04.011
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Cite this paper (APA)
Tipado, Z., Kuypers, K. P., Sorger, B., & Ramaekers, J. G. (2024). Visual hallucinations originating in the retinofugal pathway under clinical and psychedelic conditions. European Neuropsychopharmacology, 85, 10-20.