Intracranial mapping identifies high-frequency cortical dynamics underlying visual discomfort

High-contrast striped patterns near 3 cycles per degree are well established as a cause of visual discomfort and perceptual distortions, which in clinical populations can manifest as symptoms such as migraines or seizures. This sensitivity has been linked to cortical hyperexcitability, characterized by abnormally increased neural responses to visual input. Although gamma-band oscillations in visual cortex are known to reflect excitatory-inhibitory dynamics associated with pattern sensitivity, the contribution of higher-frequency neural activity and large-scale network interactions has received limited direct investigation. Using intracranial EEG recordings from patients with non-photosensitive epilepsy, we examined how aversive gratings modulate local field potential activity across frequencies ranging from 55 to 1000 Hz. Analyses focused on visual cortex as well as higher-order parietal, temporal, insular, and limbic regions, assessing frequency-specific power changes and their relationship to self-reported visual discomfort. At the group level, aversive patterns elicited significantly greater high-gamma power than control patterns in extrastriate regions (BA 18 and, at later latencies, BA 19), while primary visual cortex (BA 17) showed no consistent condition-dependent modulation. At the individual level, patients with higher visual discomfort scores exhibited stronger and more sustained post-stimulus increases in high-frequency activity in BA 18 across multiple frequency bands, accompanied by moderate-to-large effect sizes. Beyond the occipital cortex, aversive patterns engaged lateral temporal regions, predominantly in the middle and superior temporal gyri, with sustained responses emerging approximately one second after stimulus onset. Parietal responses were brief and variable across frequency bands, and insular and limbic regions showed no consistent condition-specific modulation. Ripple-band activity mirrored the high-gamma pattern in occipital and temporal cortex, whereas fast ripple and very fast ripple responses were weaker, spatially sparse, and directionally heterogeneous. Together, these results indicate that visual discomfort reflects individual differences in extrastriate cortical excitability expressed through frequency-specific network dynamics, and identify high-frequency activity in BA 18/V2 as a candidate neural correlate of susceptibility to aversive visual stimuli.