Why can light flashing at 15 to 25 times a second trigger seizures in photosensitive people? · Grey Matter

Each flash drives large numbers of neurons in the visual cortex at the same instant, so a rhythmic flash imposes synchrony from outside, and in a cortex prone to synchronise this can grow into a self-sustaining discharge.

Why can light flashing at 15 to 25 times a second trigger seizures in photosensitive people?

Each flash drives large numbers of neurons in the visual cortex at the same instant, so a rhythmic flash imposes synchrony from outside, and in a cortex prone to synchronise this can grow into a self-sustaining discharge. Flash rates of about 15 to 25 per second are the most provocative, red and high-contrast patterns are worse, and the risk grows with how much of the visual field the stimulus fills. Why some brains respond this way is only partly known, with a genetic contribution, and photosensitivity is most common in children and adolescents.