[The limbic system and the motivation process].

Understanding the part played by the limbic system in the shaping of overall behaviour is assisted by the previous study of that system's involvement in the mechanisms underlying certain sections of behaviour. a) Limbic structures contribute to the dynamic synthesis of contemporary information, by reason of their share in mechanisms: I. of modulatory central control in the production and transmission of sensory messages, 2. in the genesis of states of vigilance, especially the focussing of attention. On the other hand, they have an inhibitory role in somatic motility by way of progressive elimination of all inadequate motor response. b) Limbic structures participate in the elaboration of emotional states, in the initiation of both positive and negative reinforcement. That is to say they participate in the processes by which: I. "appetitive" or "aversive" significance is progressively conferred upon a given stimulus or situation, 2. behaviour is subjected to a positive or negative reinforcement, assuring its stabilization or its extinction. c) The comparison of the present situation with experience, enabling the organism to foresee the results of its behaviour; and similarly the comparison of results achieved with those anticipated, imply information storage, and the formation of lasting memory traces. It appears that the limbic system by integration of cognitive and affective components of sensory information, contributes to the compilation of experience which can be drawn upon in recognition or evocation. When the lasting results of different limbic lesions upon total behaviour are studied, it is clear that these effects are all the more profound as, among the motivational factors involved, those due to experience and to adaptation to environment, play the more important part. Behavioural deficits appear especially due to the absence of inhibition of certain inadequate responses, which results in a "maladaptation" of behavior as much towards present environmental conditions as to the experience of the organism. a) Regarding alimentary behaviour, the limbic system seems only to have importance in fixing the various individual attitudes towards feeding (competition, feeding habits, time to repletion, etc.). b) Sexually, experimental facts suggest that the limbic system plays an essential part in facilitation and especially selective inhibition which, by the exclusion of inadequate responses, may differentiate adult heterosexual conduct from ambivalent sexuality. Thus, in the adult, sexual behaviour can appear which is adapted to the environment, and consistent with the genetic sex and certain individual behavioural characteristics of the organism.(ABSTRACT TRUNCATED AT 400 WORDS)