[Neuropsychological observations and clinical neurology]

The term "neuropsychology" covers the study of the higher functions of man with respect to the structure and the functional organisation of the nervous system, and therefore clearly belongs to the neurological sciences. The nervous system forms a whole, composed of innumerable integrating mechanisms, ordered into a hierarchy of levels ranging from the most elementary activities, which are the most genetically determined and the most permanent, to the activities that are predominantly acquired, which are the most mobile and the most reversible ones. All parts of the nervous system--ranging from the simplest to the most complex--contain reflecting cycles, which maintain themselves in relationships of mutual dependence. The impairment of one or other activity does not mean that the function resides in the damaged part of the nervous system, but merely implies that this part is essential for its completion. The perception of an agnosia patient, the locomotor system in the case of disturbed apraxia, the reactions of a patient with disturbances in the state of consciousness, the mental capacities of a demented person, all these are the result of the global activity of a nervous system which has been depleted of certain capacities and which is curbed by new limitations. In the infinite tangle of the cerebral system, the lesion cancels one or more links which fulfil a physiological role. Depending on where the broken link is situated, the remaining functional organisation coming to the surface in this way expresses itself in a pattern of behaviour which is not strictly related. According to the principle introduced by Jackson, the lesion eliminates certain activities, and releases others, which integrate themselves into underlying levels. In this way the activities of the nervous system regress according to the opposite direction of the hierarchic evolution of their structure: from the most complex to the simplest, from the most propositional to the most automatic, from the least to the most organised.(ABSTRACT TRUNCATED AT 400 WORDS)