The Normally Functioning Reward System
Although it was long thought that dopamine was the main pleasure chemical in the brain – a claim still often heard – the evidence is now overwhelming that this is not, in fact, the case. Instead, dopamine release in reward areas appears to create a "drive state" in the brain that motivates us to move towards whatever we might need for survival, such as food. When we crave or desire anything, dopamine release in the brain appears, at least in large part, to create that feeling of desire – a feeling that will often lead to action geared towards pursuing or acquiring the object of desire.
But when delectable food, for example, is found and actually eaten, the pleasure and satisfaction that we feel from eating arises from the release of beta-endorphin in reward areas of the brain. Brain imaging studies have shown that various other pleasurable activities and behaviors – such as having sex, looking at beautiful faces, receiving money, and listening to especially pleasing music – also activate reward areas in the brain and release beta-endorphin.
A normally functioning reward system is "connected" in the sense that whatever we desire or crave – such as food – will also give us pleasure, and will generally serve our survival and reproductive prospects. Thus all animals perform actions that benefit their survival and reproduction because performing these actions or behaviors feels good. It feels good, for example, to eat and have sex. Providing a reward for behaviors such as eating and having sex by creating a feeling of pleasure, in other words, is how natural selection encouraged people and animals to behave in ways that benefited their survival and reproduction. Continue.
