Those prone to migraine headaches might want to give anything with black and white repetitive stripes, such as zebra crossings, vertical blinds and radiator grills, a wide berth.
Researchers in the Netherlands and the US have shown that some brains react in a particular way when looking at black and white bar patterns, such as barcodes or certain building designs, causing crippling headaches in those who are light sensitive and in some extreme cases they can even trigger seizures.
In a recent review of the current scientific literature, Dr. Dora Hermes, of the University Medical Centre Utrecht, The Netherlands and colleagues, found that certain types of brain waves, called gamma oscillations, are sparked by vertical black and white stripes but are not by other, more cloudier images. They found that simple alterations such as adjusting the contrast of the images or adjusting the width of the bars were enough to dampen the response to brain activity.
Although it is agreed amongst scientists that gamma oscillations are spiked when someone views black and white patterns, there is still much disagreement as to why this happens.
"Photosensitivity is common and is found in 0.3-3% of the population. Photosensitive epilepsy, where light stimulation causes seizures, has a prevalence of 1 in 10,000 individuals - or 1 in 4,000 between ages 5-24," explains Dr. Hermes.
The study highlights the need for special consideration in implementing their findings into everyday life, such as building designs, road signs and home interiors such as wallpaper and window blinds.
When asked about future work in the light of this review, Dr. Hermes remarked that, "Our commentary. . . proposes [that] the same images that drive gamma oscillations also are the most likely to trigger seizures in photosensitive epilepsy. Now, we are going to further test this idea with carefully designed empirical studies comparing patient with photosensitive epilepsy and controls."
It is still unknown as to whether a natural image, like a city scene, train station, the interior of a house or a wall painting is more likely or less likely to cause gamma oscillations or seizures.
Dr. Hermes and her team are working on models that can help predict brain activity in more diverse settings that people will encounter in everyday life.