FUNCTIONAL NETWORK DYNAMICS IN PHOTOSENSITIVE EPILEPSY AND POTENTIAL VISUAL TRIGGERS

We aim to examine how different visual stimuli elicit functional network changes and pathological EEG activity (photoparoxysmal response - PPR), in patients with photosensitive epilepsy (PSE). For this, we conducted a retro- and prospective study in PSE patients.
The study cohort includes healthy controls (HC), PSE patients, and non-PSE epilepsy patients. As stimulation, our retrospective study used white flickering light (1-60 Hz), while our prospective study introduces novel stimuli varying in chromaticity, field size, luminance, and emotional content, all under 10–20 EEG monitoring. Visual discomfort ratings (0-10) are also collected.
The retrospective study revealed significantly elevated occipital PPR power in PSE patients compared to HC during 10-20 Hz stimulation. In contrast, increased visual cortex excitability (characterized by P100 amplitude and steady-state visual evoked potentials) was observed only in the most severe PSE subtype. Instead, PSE patients exhibited increased anterior–posterior connectivity in the 3-4 Hz PPR band. Preliminary results from our prospective study show similar trends, with higher PPR power in PSE patients in response to higher-risk stimuli, correlating with greater subjective visual discomfort. Hyperconnectivity appears more pronounced under these conditions but requires confirmation in a larger sample.
Overall, the retrospective findings provide novel evidence that altered network dynamics in PSE patients may be a prerequisite for PPR propagation and subtype-specific responses. The prospective study aims to use these neural measures and subjective discomfort ratings to better characterize the brain dynamics underlying PSE and to identify harmful visual content in the context of advancing visual technologies.