After a carbon monoxide intoxication with coma of short duration, a 25 years-old man sustained a demential state and during the first weeks, a mild extrapyramidal syndrome. One year later, the mental state had progressively improved, although with a severe anterograde amnesia but the clinical picture had become unique. Let without external stimulation, the patient remained inert without any activity, often lying on his bed but not sleeping. He had lost any initiative. At the opposite, if he was stimulated, his physical, intellectual and affective performances were nearly normal, verbal fluency remaining however poor. Psychic self-activation appeared to be lost but psychic possibilities after external stimulation were nearly normal. When inactive, the patient was occupied with a mental compulsive activity. C.A.T. showed bilateral necrotizing lesions in the globus pallidus. The present case is very similar to a previously reported one. (D. Laplane et al., Rev. Neurol., 1981, 137 : 269-276) in which bilateral lenticular lesions produced the same syndrome. The pallidal area seems to play a determinant role in the processes of self-activation of psychic life.