The visual cortex is the part of the cerebral cortex that receives and processes sensory nerve impulses from the eyes. It is located in the occipital lobe in the back of the brain. A recent article on sciencealert.com reports a study that may link disturbances in the visual cortex to migraines. The University of Birmingham, UK, conducted the relatively small study, but in the 29 volunteers who suffered from migraines, the visual cortex was found to be more excitable and more responsive in a series of tests. Study participants were shown a striped grating pattern and then asked to rate how uncomfortable it was to look at, and to log any other visual phenomena associated with looking at it. Electroencephalogram (EEG) tests were used to track and record the brain waves of the volunteers. The migraine sufferers showed a larger response in their visual cortices during both the pattern and EEG experiments.
It is known that many migraines are concomitant with aura. That is, sensory disturbances that include flashes of light, blind spots and other vision changes. Migraine sufferers also often suffer from severe photosensitivity during an episode. This led researchers to investigate the possibility of an eye-brain connection in migraines. In 2018, the NIH published a study that found females with migraine with aura have a thicker visual cortex, possibly due to increased neuronal density in that area of the brain. A 2019 study published in The Journal of Headache and Pain found disrupted visual network connectivity in migraine without aura using magnetic resonance imaging (MRI).
Estimates are that one in seven people suffer from migraines worldwide, but the causes are uncertain. When the pain can last for days and interfere with daily functioning, migraines can affect work, family and quality of life. Treatments are geared toward reducing pain during an episode and medications to reduce frequency and severity. Identifying a condition such as an abnormality in the visual cortex provides another avenue for research into treatment and prevention. This latest study from the UK provides the first evidence for the link between migraines and abnormalities in the visual cortex by identifying a specific brain response pattern among migraine sufferers. "Our study provides evidence that there are likely specific anomalies present in the way the visual cortex of migraine sufferers processes information from the outside world," says neuroscientist Ali Mazaheri, from the University of Birmingham.
To learn more about the anatomy and physiology of the eye and its connection with the brain, go to our CE, Check Your Eye Development IQ, at 2020mag.com/ce.