[The neuroanatomy of motivation in man]

To relate motivation, a psychological concept, to a neurobiological substrate requires that this concept should be translated in operations relevant at the biological level. The term of motivation includes mental elementary processes decoding the emotional value of a stimulus (endogenous or exogenous) and integrating it into the elaboration, control and execution of goal-directed behaviors in order to ensure the maintenance of homeostasis, the well-being and survival of the individual and the species. Thus, in experimental condition, responses to aversive or appetitive situations are the classical markers of motivation. Consequently, the cerebral network of motivation particularly relates to the limbic system, i.e., the amygdala, the orbital and ventromedial prefrontal cortex, the anterior cingulum and the ventral striatum. Within this network, it is possible to distinguish: on one part structures such as the orbital and ventromedial prefrontal cortex, which are essential for the highest level of adaptive responses, allowing the individual to decode the variations of the emotional contingencies in real time, to integrate them into the behavior, and to maintain a behavioral choice during a long course, regardless of endogenous or environmental constraints; on the other part structures like the amygdala allow to build stable and invariants behaviors, that can be automatically activated and are essential for survival and avoidance of noxious situations.