Photosensitivity to flashing lights and even certain still images can trigger stunning results. A particular episode of Pokémon sent 685 people in Japan to the hospital. Researchers at the University Medical Center (UMC) Utrecht in the Netherlands and New York University explore this effect by examining certain images, such as black and white bar patterns, which can cause a pattern of neural activity in the brain known as gamma oscillations. According to the researchers, it’s possible that such images are responsible for other problems, such as migraine headaches, particularly in people who are generally sensitive to light. The researchers conclude that gamma-oscillation-provoking images are also most likely to trigger seizures. They advise that there are simple ways to adjust an image to dampen the pattern of brain activity, such as reducing the contrast, adjusting the width of the bars, or shifting the image from a grate design to something more like plaid. They further propose that the link between images that trigger photosensitive epilepsy and normal brain activity is particular to gamma oscillations, and not to other forms or neuronal responses. The researchers are now designing studies to explore these patterns of brain response in patients with photosensitive epilepsy and those without.