[Loss of psychic self-activation].

Loss of motivation is a well-known disorder in patients with frontal lesions or, as more recently described, with bipallidal lesions. Some of these patients also report a kind of fading of their mental life when they are without exogenous stimulation. Yet their performances return to normal (or almost normal) levels under the influence of a social stimulation. It is this dissociation which we propose to call "loss of psychic self-activation" (LPSA). Comparisons with disorders produced by similar lesions suggest that this is not an "all or none" phenomenon. The purpose of this paper is to discuss the originality, usefulness and validity of the loss of psychic self-activation concept and to evaluate its heuristic value, notably in its application to Janet's psychasthenia and to obsessional neurosis. An interpretation of this disorder based on the available anatomical data is also tentatively proposed.