Flicker light stimulation induces thalamocortical hyperconnectivity with LGN and higher-order thalamic nuclei.
Ioanna Amaya, Marianna E. Schmidt, Marie T Bartossek, Johanna Kemmerer, Evgeniya Kirilina, Till Nierhaus, Timo T Schmidt
Imaging Neuroscience 2023 DOI: 10.1162/imag_a_00033 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Experimental study Peer reviewed |
|---|---|
| Population | Healthy participants |
| Intervention | Flicker light stimulation |
| Topics | Altered states of consciousness |
| Keywords | Flicker light stimulation Functional connectivity Thalamic nuclei Thalamocortical connectivity Visual hallucinations Visual hierarchy |
| Key findings | FLS induces thalamocortical hyperconnectivity between LGN, early visual areas, and proximal upstream ventral visual stream areas, with higher-order thalamic nuclei showing frequency-dependent connectivity changes that reflect increases in visual phenomena. |
Abstract
The thalamus is primarily known as a relay for sensory information; however, it also critically contributes to higher-order cortical processing and coordination. Thalamocortical hyperconnectivity is associated with hallucinatory phenomena that occur in various psychopathologies (e.g., psychosis, migraine aura) and altered states of consciousness (ASC; e.g., induced by psychedelic drugs). However, the exact functional contribution of thalamocortical hyperconnectivity in forming hallucinatory experiences is unclear. Flicker light stimulation (FLS) can be used as an experimental tool to induce transient visual hallucinatory phenomena in healthy participants. Here, we use FLS in combination with fMRI to test how FLS modulates thalamocortical connectivity between specific thalamic nuclei and visual areas. We show that FLS induces thalamocortical hyperconnectivity between lateral geniculate nucleus (LGN), early visual areas, and proximal upstream areas of the ventral visual stream (e.g., hV4, VO1). Further, an exploratory analysis indicates specific higher-order thalamic nuclei, such as anterior and mediodorsal nuclei, to be strongly affected by FLS. Here, the connectivity changes to upstream cortical visual areas directly reflect a frequency-dependent increase in experienced visual phenomena. Together, these findings contribute to the identification of specific thalamocortical interactions in the emergence of visual hallucinations.
Comparable studies
Other experimental studies on altered states of consciousness, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| The Standardized Psychometric Assessment of Altered States of Consciousness (ASCs) in Humans Healthy subjects in six countries | 1998 | Experimental and field study | n = 1,133 |
| TMS-EEG and resting-state EEG applied to altered states of consciousness: oscillations, complexity, and phenomenology. | 2023 | Experimental study | |
| A Test of the Psychedelic Model of Altered States of Consciousness | 1976 | Experimental study with comparison groups | |
| Neural Correlates of Non-ordinary States of Consciousness in Pranayama Practitioners: The Role of Slow Nasal Breathing Experienced meditators | 2022 | Within-subjects comparison | n = 12 |
| Increased spontaneous EEG signal diversity during stroboscopically-induced altered states of consciousness Healthy adults | 2019 | Experimental study |
Citations in the library
Cited by 4
- Classification schemes of altered states of consciousness. Neuroscience & Biobehavioral Reviews August 1, 2025
- Thalamocortical interactions reflecting the intensity of flicker light-induced visual hallucinatory phenomena. Network Neuroscience 2025
- Stroboscopic light stimulation as a controllable probe of the psilocybin state: a mechanistic framework and a falsifiable prediction Frontiers in Pharmacology September 30, 2026
- Measuring the contents of hallucinations from psychedelics and stroboscopic light: the Six-Dimensional Visual Hallucination Questionnaire Royal Society Open Science September 2, 2026
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