Training causes activation increase in parietal and temporo-parietal regions in children with developmental dyscalculia

Children with developmental dyscalculia (DD) differ from typically developing (TD) children regarding brain activation. While arithmetic training reduces fronto-temporo-parietal activation related to domain-general processes in TD children, we do not know whether these findings also hold for children with DD. Since children with DD are one main target group for intervention and remediation, it is essential to know how arithmetic training that improves arithmetic performance induces brain activation changes in these children. In a within-participant design, a group of 20 children with DD underwent two weeks of training in simple and complex multiplication. Brain activation was measured using functional near-infrared spectroscopy (fNIRS) before and after training to assess training-related changes. Two weeks of training led to increased temporo-parietal activation for trained versus untrained simple multiplication. For both trained and untrained complex multiplication, widespread increases in activation were observed in frontal, parietal, and temporo-parietal cortices. Interestingly, training-specific activation increases were observed only in the bilateral parietal cortex, but not in the other regions. These brain activation changes were more robust in younger children. We conclude that in contradiction to the training-related brain activation decreases seen in studies of TD children, children with DD showed improved behavioral performance along with increased brain activation. Therefore, using neuroimaging techniques such as fNIRS on children with DD provided valuable insights about strategy changes and the neural networks involved in mental arithmetic.