Your Brain: The Missing Manual

Pleasure: The Reward System

Quick, what do sex, a job promotion, and the act of defecation all have in common? Shortly after the act is complete, your brain rewards you with a brief flash of pleasure to let you know your life is on track.

Pleasure is the brain's reward system. It encourages you to pursue the activities that are in your biological best interests—activities that keep you healthy, well fed, and in top procreating form. Pleasure also greases the wheels of social interaction, helping you form lasting alliances with your own kind.

The nucleus accumbens is the leading candidate for the brain's pleasure center. When rats were given the chance to electrically stimulate this area in their brains, they hit the lever thousands of times an hour, showed no interest in food or mates, and eventually died of exhaustion. In other words, you may think you love sex, money, and chocolate cake, but what you really want is something a whole lot better: the tiny current of electricity that your brain uses to reward you.

Figure 6-1. 

The nucleus accumbens may be the part of your brain that generates the feeling of pleasure, but it doesn't work on its own. A region called the ventral tegmental area (VTA) sits at the very core of your brain and receives all sorts of information that indicates how well you're doing in satisfying your biological needs. It then tells the nucleus accumbens to dispense ...