"When you startle, you close your eyes. But what can this blink of an eye tell us about anxiety? In neuroscience, we use the startle reflex to study anxiety. We measure the electrical activity of the muscle that closes the eye, the orbicularis oculi muscle. We then measure these responses from onset to peak, so each signal represents one eye blink. The startle reflex gives us an idea of what happens in the brain. When we startle, nerve cells start to fire, which are located in the brain stem. We startle more when we're in danger. This is modulated by the amygdala, the fear center of the brain. So if you see a countdown but nothing else happens, then you might not startle as much. But if you know that something aversive is coming, like a scream, then your startle reflex is stronger. With this experiment, we can increase the startle reflex in the lab, and we use experiments like this to study patients suffering from anxiety disorders and those unaffected. Understanding how the human brain processes anxiety might help us to advance treatments for patients with anxiety disorders. But it all starts like this, with a blink of an eye."