Selective Preservation of Exceptional Arithmetical Knowledge in a Demented Patient

Abstract
Neuropsychological methodology is generally founded on the description of functional dissociation after focal brain damage. The observation of exceptional abilities can also constitute a means of documenting the different cognitive systems. In this study, we report the performance of a demented elderly patient who, although he had impaired functions in several cognitive domains, showed exceptional calculating abilities, superior to those of young adults. This case study deals with the problem of various mathematical dissociations at different levels.