Neuropsychology of Number Processing and Mathematical Disorders: from the past to the Future

Research on mathematical disorders and their brain mechanisms has a long tradition. This paper presents the history of the search for the mechanisms of aquired acalculia from the perspective of clinical neuropsychology. The classic typologies of this disorder formed by Berger and Hecaen are discussed, as well as modern trends in the research on specific arithmetic difficulties in children. The latest general models of number processing (McClo skey, Dehaene, Butterworth, Zorzi) constructed within cognitive neuropsychology are included. Recently, new technologies of neuroimaging are being applied in research carried out within clinical and experimental cognitive neuropsychology. Neuroimaging technology (fMRI, PET) opens up opportunities to study the neural basis of number processing. On the other hand, these methods must be employed with care and the conclusions should be drawn within a broader, biopsychosocial context. Otherwise, there is the risk that a person with disorders will be reduced solely to an object of experiments. Furthermore, the neuroimaging results may lead merely to the development of "neurophrenology." Such tendencies in research raise questions about its methodological limitations.