Cannard, C., Vieten, C., Yount, G., Vega, M., Kayale, F., & Delorme, A. (2025). Investigating the Brain Processes Underlying an Unusual Visual Experience: A Case Study. Journal of Anomalous Experience and Cognition, 5(2), 136–167. https://doi.org/10.31156/jaex.25894 h
Abstract
Background: This case study investigated the neural correlates of an unusual visual experience in which an individual constantly perceives highly detailed holographic images overlaid on his visual field and can modulate them to an extent. We named this experience Upsight. Our aim was to assess how the phenomenon may relate or differ from visual mental imagery (VMI such as hyperphantasia), imagination, or visual hallucinations (e.g., Charles Bonnet Syndrome).
Methods: EEG (64-channels) data were collected while the participant alternated between 30-second trials of Upsight and visual mental imagery (VMI) conditions (200 trials each). We conducted power spectral density (scalp and source levels) as well as source functional connectivity (FC) analyses, as well as robust statistics to test the null hypothesis of an absence of a difference (nonparametric statistics and spatiotemporal cluster corrections).
Results: Scalp results revealed that, relative to VMI, the Upsight experience was characterized by strong alpha and delta power decreases (widespread with a peak in posterior regions), and gamma power increase (29-45 Hz) in the right frontal and left posterior regions, supporting increased engagement of cognitive and visual processes. Similarly, after source localization, we observed a strong decrease in both spectral power and FC in the alpha frequency band, in brain areas involved in visual processing, spatial orientation, and sensory integration, reflecting increased cortical activation of these areas and brain networks.
Conclusions: Upsight involves heightened engagement and processing in visual and cognitive networks relative to VMI. We discuss the phenomenology and results in relation to VMI, imagination, and visual hallucinations.
