Bridging brain and behavior in Developmental Dyscalculia: a combined EEG and neuropsychological study.

Developmental dyscalculia (DD) is a neurodevelopmental disorder characterized by persistent difficulties in numerical processing and arithmetic learning, which occur independently of intellectual ability or inadequate educational exposure [1]. Recent advances in cognitive neuroscience have begun to elucidate the neuropsychological framework of DD, highlighting alterations in both domain-specific (e.g., numerical representation) and domain-general (e.g., executive functioning) systems [2]. Electroencephalography (EEG) provides distinct advantages due to its high temporal resolution, enabling the investigation of real-time neural dynamics involved in numerical cognition. To explore the neural mechanisms supporting mathematical competence in DD, we studied 12 young adults with a formal diagnosis of DD and compared their performance and neural activity to that of a matched control group. EEG activity was recorded from 128 scalp electrodes while participants engaged in arithmetic tasks involving addition, subtraction, and multiplication. During each trial, participants evaluated the accuracy of a presented solution by indicating whether it was correct or incorrect. Behavioral data, including reaction times, error rates, and omitted responses, were recorded. Additionally, participants completed a battery of pen-and-paper neuropsychological tests designed to assess attention, executive functioning, verbal abilities, general cognitive performance, and foundational mathematical skills. Throughout the experimental session, autonomic nervous system activity was monitored, with specific measures including heart rate variability and skin conductance levels. Our results reveal that DD is associated with atypical event-related potentials during number-related tasks. Specifically, significant alterations were observed in the P100 and N200 components across all tasks, reflected in differences in amplitude, latency, and topographical distribution, with a marked reduction in activity over the left hemisphere. Source localization analyses further indicated distinct activation patterns, with significant differences emerging in the superior parietal lobules and left entorhinal cortex. Neuropsychological testing revealed good performance on the Trail Making Test, categorical fluency, the Corsi Block-Tapping Test, and the number transcription task. However, the participant reported difficulties across all mental calculation tasks. Notably, autonomic nervous system activity during neuropsychological testing was elevated in participants with DD compared to control subjects. These findings support the hypothesis that DD involves both domain-specific impairments in numerical processing and broader disruptions in domain-general cognitive functions. The high temporal resolution of EEG provides valuable insights into the real-time neural processing abnormalities characteristic of DD, offering potential biomarkers that may complement traditional neuropsychological assessments in diagnosis.