Читать книгу Anxiety For Dummies - W. Doyle Gentry, Laura L. Smith - Страница 46

Think of the brain as having many interconnected circuits. One circuit involves both the limbic system and the frontal lobes. To keep it simple, the limbic system is a primitive region of the brain and is responsible for immediate reflexive responses to threat. The thalamus and the amygdala form part of the limbic system. The frontal lobes, which handle judgment and reasoning, respond more slowly and thoughtfully.

When the brain perceives something as being dangerous, it immediately registers in the brain’s control center known as the thalamus. The thalamus rapidly sends a signal directly to the amygdala, which activates reflexive fear responses. Those responses prepare the body to fight or flee. The thalamus also delivers a warning signal through the frontal lobes. The frontal lobes, where rational thought occurs, take a little more time and use reason and logic to determine the veracity of the incoming threat. That’s why when you perceive something as being scary, your body immediately responds with a rapid heartbeat, tension, and dread. If and when the rational frontal lobes figure out that the scary thing actually doesn’t pose a significant threat, you calm down. That’s the way the brain is supposed to work.

For example, around the Fourth of July you hear loud popping sounds. Your limbic system may initially interpret those as gunshots, but your frontal lobes take a few seconds longer and conclude that the sounds are likely to be firecrackers. However, dogs, who don’t understand calendars or have well-developed frontal lobes, remain fearful.

In anxiety disorders, either the limbic system or the frontal lobes (or both) may fail to function properly. Thus, the limbic system may trigger fear responses too easily and too often, or the frontal lobes may fail to use logic to quell fears set off by the limbic system. When the brain signals danger, the body responds by getting ready for action. The next section explains the chemical aspects of fear.