Migraine affects 1 in 4 women and 1 in 12 men. Besides a debilitating headache and nausea, some people experience distorted vision, dizziness, tingles, numbness, or speech difficulties. Some experience migraine infrequently, others endure it several times a week, severely disrupting their everyday life and quality of life. Often the cause of migraine is unknown, but striped patterns or flickering light can trigger an attack. This research will investigate how visual patterns induce migraine and why only some people are affected. One of the aims of this work is to produce guidelines to prevent visually triggered attacks.Migraine sufferers are usually considered free from symptoms between attacks, but subtle differences to people without migraine emerge with some tests, which have been attributed to altered excitability of cells in certain brain areas (the cortex). This research also examines cortical excitability in migraine, which may lead to treatments or clinically useful screening tests.