Magnitude and spatial processing in dyscalculia of genetic origin and of unknown etiology: a combined investigation of behavioral and brain imaging data

Dyscalculia has been frequently reported in a variety of genetic disorders such as Turner syndrome, Fragile-X syndrome, and Williams syndrome. Deficient spatial processing is another common cognitive characteristic of individuals suffering from genetic disorders. However, most of the respective studies focused on the behavioral assessment of higher-level arithmetical skills and did not investigate systematically the potential link between numerical and spatial cognition. As regards the brain areas mediating calculation, there is converging evidence that specific components of number processing are mediated by segregated parietal brain regions in adults. Nonetheless, far less is known about the neurocognitive trajectories of typical and atypical numerical development. Thus, the main aims of the proposed study are threefold: 1) to assess the neural correlates of basic numerical skills (i.e., symbolic and non-symbolic magnitude processing) in healthy control children as well as in children exhibiting numeracy deficits associated with genetic disorders and those of unknown etiology; 2) to investigate whether common brain/cognitive systems are affected in children displaying numeracy deficits of various origins; and finally 3) to investigate whether magnitude and spatial processing are sub served by identical brain regions (see ATOM theory; Walsh, 2003) and if so, whether the link between numerical and spatial cognition is task-specific or group-specific (i.e., differentially vulnerable to numeracy deficits). The proposed project is unique as it is the first that aims at merging behavioral and brain-imaging data to study magnitude and spatial processing in healthy children as well as children displaying numeracy deficits (of various origins). Moreover, the proposed study could serve as a baseline for a large-scale study investigating the existence of candidate genes for dyscalculia.