 |
| Dirk Jancke (left) und Callum White haben für das Paper zusammengearbeitet. Photo Credit: © RUB, Marquard |
Scientific Frontline: "At a Glance" Summary
- Main Discovery: High-resolution brain imaging reveals that psychedelics suppress external visual processing and instead drive visual areas to access the retrosplenial cortex, a region responsible for retrieving memory contents and associations, thereby generating hallucinations.
- Methodology: Researchers utilized an optical imaging method to record real-time neural activity across the entire brain surface of genetically modified mice, tracking fluorescent proteins expressed specifically in pyramidal cells within cortical layers 2/3 and 5.
- Key Data: The administration of psychedelics intensified low-frequency neural activity waves, specifically triggering spontaneous and evoked 5-Hz oscillations in visual brain areas and the retrosplenial cortex through activation of the serotonin 5-HT2A receptor.
- Significance: The findings map the precise neural mechanisms behind visual hallucinations, demonstrating that psychedelics shift the brain into a state akin to partial dreaming where external sensory input is hindered and internal memory fragments fill the perceptual gap.
- Future Application: This mechanistic understanding supports targeted psychiatric therapies that use psychedelics under medical supervision to help patients selectively access positive memories and unlearn entrenched negative thought patterns associated with anxiety and depression.
- Branch of Science: Neuroscience, Psychopharmacology, Psychiatry
- Additional Detail: The targeted 5-HT2A serotonin receptor exhibits the highest affinity for psychedelics and primarily mediates the suppressive effects on external visual processing while modulating the learning centers of the brain.
Psychedelic substances are increasingly being used under medical supervision to treat anxiety disorders and depression. However, the mechanisms by which these substances influence our perception and consciousness are largely unknown. A research team from Hong Kong, Singapore, and Ruhr University Bochum, Germany, has now, for the first time, shown high-resolution images of brain activities in an animal model after the administration of psychedelics. The scientists discovered that visual processes increasingly access brain regions that retrieve memory contents and associations. This could explain how visual hallucinations arise. The scientists report in Communications Biology on February 11, 2026.
Hallucinations fill the gap
Psychedelics activate a specific serotonin receptor. At least 14 different receptors are known where the neurotransmitter serotonin binds. Psychedelics have the highest affinity for the 2A receptor, which, among other effects, acts suppressive in the visual brain and influences learning processes. “We have observed in earlier studies that visual processes in the brain are suppressed by this receptor,” says Callum White, first author of the study. “This means that visual information about things happening in the outside world becomes less accessible to our consciousness. To fill this gap in the puzzle, our brain inserts fragments from memory – it hallucinates.”
Short-term oscillations trigger communication between brain areas
In their current study, the authors show how this happens. Psychedelics intensify oscillations in visual brain areas. Generally speaking, oscillations are synchronized neural activity waves that modulate communication between brain regions. After administration of psychedelics, the scientist found that visual areas produce increasingly low-frequency (5-Hz) activity waves that activate another brain region, the retrosplenial cortex. This area forms a major hub for the exchange with stored information. The brain thus switches to a new mode in which access to ongoing events is hindered, and instead perceptions are increasingly generated from memory contents, “a bit like partial dreaming,” says Professor Dirk Jancke, leader of the study.
Visualizing the dynamics of brain activity in real-time
To visualize these complex processes, the scientists use an optical method that records neural activity in real-time over the entire brain surface. The mice developed by Professor Thomas Knöpfel from Hong Kong Baptist University are genetically manipulated so that they express fluorescent proteins in defined cell types. “We therefore know exactly in our experiments that the measured fluorescent signals originate from pyramidal cells of the cortical layers 2/3 and 5, which mediate communication within and between brain regions,” says Jancke.
Developing new therapy approaches
The results support new approaches in psychology that use psychedelics to treat, for example, anxiety disorders or depression. “When used under medical supervision, such substances can temporarily change the state of the brain to selectively recall positive memory content and restructure learned, excessively negative thought patterns, i.e., to be able to unlearn negative context. It will be exciting to see how such therapies are further personalized in the future,” says Jancke.
Funding: The study was partly funded by the Deutsche Forschungsgemeinschaft through the Research Training Group (RTG 2862/1) “Monoaminergic Neuronal Networks & Disease” (MoNN&Di) and the Collaborative Research Center (CRC) 874.
Published in journal: Communications Biology
Authors: Callum M. White, Zohre Azimi, Robert Staadt, Chenchen Song, Thomas Knöpfel, and Dirk Jancke
Source/Credit: Ruhr-Universität Bochum
Reference Number: ns021326_01