[Neurochemical mechanisms of a need, motivation and goal-directed behavior].

In this review is analyzed four kinds of needs, which include both humans and animals. These are: 1--the need to eat 2--need to drink 3--sexual need and, 4--the need to enhance or prolong the positive emotional state, and conversely, the need to dispose or avoid pain and unpleasant effects or negative emotional state. The centers of the first three needs are localized in the hypothalamus.