Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, C077

Oral Communications

Neural mechanisms of numerical processing in typically developing children and children with dyscalculia

S. Üstün5, N. Ayyildiz1, E. H. Kale1, O. Mance Calisir1, P. Uran Senol2, O. Oner3, S. Olkun4, M. Cicek5,1

1. Brain Research Center, Ankara University, Ankara, Turkey. 2. Department of Child Psychiatry, Ankara University, Faculty of Medicine, Ankara, Turkey. 3. Department of Child Psychiatry, Bahcesehir University Faculty of Medicine, Ankara, Turkey. 4. Department of Mathematics and Science Education, Ted University, Faculty of Education, Ankara, Turkey. 5. Department of Physiology, Ankara University, Faculty of Medicine, Ankara, Turkey.

Dyscalculia is a learning disability affecting the acquisition of arithmetical skills in children with normal intelligence and age-appropriate education. There are two main hypotheses about dyscalculia: The deficit in quantity processing and the deficit in matching quantities with symbols. It is still unclear which neural mechanisms are related with dyscalculia. In this study, number processing in children with dyscalculia and typically developing children were examined via functional magnetic resonance imaging (fMRI). The first stage of the study, we tested 1944 third-grade students (7-9,5 years) in elementary schools with Mathematics-and-Arithmetic-Performance-Tests, and Raven-Progressive-Matrices-Test for fluid intelligence. Secondly, determined children were tested two-years later with mathematics tests and Weschler-Intelligence-Scale-for-Children, and evaluated by child psychiatrists. After co-morbidities were eliminated, the dyscalculia (n=12, mean age: 11.25) and control (n=15, mean age: 11.26) groups were precisely identified. Participants were asked to perform a numerosity comparison paradigm while undergoing fMRI scan. Paradigm consists of two types of number sense condition and two difficulty levels. Imaging data is analyzed with repeated measures ANOVA with group (dyscalculia and control), number sense (symbol and dot) and difficulty (0.5 and 0.7 ratios) as factors via a MATLAB toolbox SPM12. Intelligence quotient and age of participants were added as covariates. The main effect of number activations was bilateral intraparietal sulcus (IPS), dorsolateral prefrontal cortex (DLPFC). The main effect of difficulty activations was bilateral insular cortex, anterior cingulate cortex. For the main effect of group orbitofrontal cortex and ventromedial prefrontal cortex was activated. For group and number interaction hippocampus was activated. A region of interest (ROI) analysis which performed on hippocampal region showed that hippocampus only activated during symbol comparison condition at dyscalculia group. In the number sense literature, it is suggested that IPS is related to perceiving numerosity and DLPFC is responsible for the cognitive control (attention, memory) which related to numerosity. The frontoparietal network which activated in number task is in line with the literature. The neural network which consists of insular cortex and anterior cingulate cortex activated in the main effect of difficulty. This network is called salience network and it is related to orienting attention to the task. Frontal activation in dyscalculia could be related to the requirement of more cognitive control as a result of a deficiency of parietal mechanism which related to basic number sense. Hippocampal activation in the symbol condition showed that patients with dyscalculia needed to access memory during the task. This might be caused by the deficit in matching symbols and quantities.

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