Introduction. We believe that it is of great interest, in neuropediatric clinic, to value the molar behavior disorders and to accomplish the corresponding molecular alterations in the central nervous system. Patients and methods. We studied 26 patients diagnosed of serious disorders of the development, that were presenting a typical clinic with manual stereotypes. We choose at random 5 children to practice them a study of metabolic neuroimaging through the Positron Emission Tomography with 18Fluoro-Deoxi-Glucose (PET-FDG). Results and conclusions. The conclusion, more meaningful, is that the children with serious disorders of the development present a mature failure in the neurofunction circuits of the thalamus, as well as the cortical connection and association areas. This clinical situation is reinforced by the results of the PET-FDG, that presents a characteristic metabolic image of the autism children, with a bilateral decrease of the captation of FDG, mainly in regions as thalamus, frontal and temporary lobes [REV NEUROL 1999; 28 (Supl 2): S 124-30].