Multimodal imaging of parietal brain networks in adults and children with developmental dyscalculia

It is estimated that 3-6% of children and adults have Developmental Dyscalculia (DD). Impaired mathematical skills have a considerable cost to the individual. For example, the recent Government Office for Science Foresight project Mental Capital and Wellbeing (2008) estimated that having developmental dyscalculia reduced lifetime earnings by #114,000 and reduced the probability of achieving 5 or more GCSEs (A*-C) by 7 ? 20 percentage points. There is also a cost to society, as those with dyscalculia are twice as likely to be unemployed as non-affected individuals, and a potential mental health cost, as it has been estimated that having dyscalculia raises the risk of depression 3-fold (Butterworth, 2008). Having a better understanding of the underlying causes of dyscalculia would improve our ability to detect early in life who is at risk, and also improve the remediation that we can offer. Our project should provide (1) a much more elaborate theoretical understanding of DD than currently available, (2) clear recommendations for identification methods for DD, (3) potential avenues for developing remediation for DD.

It is estimated that 3-6% of children and adults have Developmental Dyscalculia (DD) which is a persistent mathematical disability of developmental origin. Despite the large number of people affected, there is no generally accepted functional definition of Dyscalculia, and nothing certain is known about its aetiology and neural origins. Currently the most prominent neuroscience theory suggests that DD is due to the impairment of a neural representation of number (magnitude representation: MR) residing in the horizontal intraparietal sulci of the brain. We identify several problems with the research underlying this hypothesis. In addition we show that psychological behavioural research provides alternative explanations of DD which could also explain the consistently-observed parietal deficit. According to these explanations DD may be due to the impairment of working memory (WM) and/or inhibitory control, the ability to resist interference from other cognitive or motor input (IC). To assess competing explanations, our proposal aims to examine the MR, WM and IC theories of DD in a single framework using the same subjects. This will help determine to what extent the impairment of MR, WM and IC contributes to DD and whether/how each cognitive process contributes to the observed parietal dysfunction.
We plan to test 26 primary school children, 26 high-school children and 20 adults with DD. Gender, age and education-matched control subjects will be paired with each group. High-school children and adults will be tested with both functional magnetic resonance imaging (fMRI) and electro-encephalography (EEG). Primary school children will be tested with EEG. fMRI provides anatomical accuracy. EEG provides excellent temporal resolution. Three experiments will be run with each subject group. Experiment 1 will use the most up-to-date paradigm for identifying the MR: neural adaptation to non-symbolic magnitudes. Experiment 2 will examine the automatic activation of symbolic magnitudes and IC. Experiment 3 will examine both visual and phonological WM. Comparing DD and control subjects will enable us to separate the contribution of MR, WM and IC deficit to DD