Neural correlates of stroboscopic stimulation to test a model of psychedelic hallucination

Stroboscopic (strobe) hallucinations are geometric percepts elicited by flickering full-field illumination at specific frequencies. They bear a striking resemblance to the kaleidoscopic imagery induced by hallucinogenic psychedelics. As such, they have the potential to serve as an experimental model for studying these altered states of consciousness in a controlled manner. However, it remains unclear if these similar perceptual experiences share the same underlying neural correlates. To address this question, we studied three EEG signatures associated with hallucinogen administration: alpha power reduction, increased signal complexity, and the flattening of the 1⁄f slope. These EEG signatures were measured during hallucinatory (11Hz - 19Hz) and non-hallucinatory (51Hz – 59Hz) strobe stimulation. It was hypothesized that hallucinatory stimulation would elicit EEG modulations like those observed during hallucinogen administration. Our findings revealed that strobe stimulation induced a brain state remarkably similar to the one induced by hallucinogens. This brain state persists even after strobe stimulation has ceased. However, this brain state was elicited by both hallucination and non-hallucination inducing frequencies. Our results suggest that stroboscopic stimulation, in general, offers a viable experimental model for studying the hallucinogenic brain. However, new measures are needed to serve as neural correlates of geometric hallucinations.