The reward systems of the brain are a group of brain structures that are activated whenever we experience something that brings pleasure, such as eating good food, sex, or using an addictive drug.
It is important to note that these structures are actually activated when people are anticipating and thinking about a reward, but not when they are actually consuming or enjoying the reward, as other brain structures take over.
The bigger the reward and the more likely one is to receive the reward, the greater the activation in these structures, which forms the basis for addiction. Activation of these structures increases the likelihood of repeating the behavior in the future.
Studies found that these structures play a crucial role in positive emotions, such as those related to prosocial behaviors, and conversely damage to these structures makes it difficult to experience positive emotions. Paradoxically, the reward pathway is also involved in negative emotions like shame.
Dopamine is the main neurotransmitter of the brain reward pathway; when exposed to something pleasurable, the brain responds by releasing dopamine. Dopamine release is behind the motivation to repeat a pleasurable experience.
The nucleus accumbens, one of the structures in the brain reward systems, connects with the amygdala which is involved in emotion processing, thereby attributing feelings to a pleasurable experience. Thus, after eating good food, the amygdala would contribute to the positive experience with feelings of enjoyment and happiness.