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Effective connectivity of the multiplication network: A functional MRI and multivariate granger causality mapping study

Authors

  • Frank Krueger,

    Corresponding author
    1. Department of Molecular Neuroscience, George Mason University, Fairfax
    • Department of Molecular Neuroscience, Krasnow Institute for Advanced Study, George Mason University, 4400 University Drive, MSN: 1G3, Fairfax, VA 22030
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    • These authors contributed equally to this work.

  • Steffen Landgraf,

    1. Department of Psychology, Humboldt University, Berlin, Germany
    2. University Pierre and Marie Curie, Paris VI, France
    3. Center for Psychiatry and Neuroscience, INSERM U894, Sainte Anne Hospital, Paris, France
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    • These authors contributed equally to this work.

  • Elke van der Meer,

    1. Department of Psychology, Humboldt University, Berlin, Germany
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  • Gopikrishna Deshpande,

    1. Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, Georgia
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  • Xiaoping Hu

    1. Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, Georgia
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Abstract

Developmental neuropsychology and functional neuroimaging evidence indicates that simple and complex mental calculation is subserved by a fronto-parietal network. However, the effective connectivity (connection direction and strength) among regions within the fronto-parietal network is still unexplored. Combining event-related fMRI and multivariate Granger Causality Mapping (GCM), we administered a multiplication verification task to healthy participants asking them to solve single and double-digit multiplications. The goals of our study were first, to identify the effective connectivity of the multiplication network, and second, to compare the effective connectivity patterns between a low and a high arithmetical competence (AC) group. The manipulation of multiplication difficulty revealed a fronto-parietal network encompassing bilateral intraparietal sulcus (IPS), left pre-supplementary motor area (PreSMA), left precentral gyrus (PreCG), and right dorsolateral prefrontal cortex (DLPFC). The network was driven by an intraparietal IPS-IPS circuit hosting a representation of numerical quantity intertwined with a fronto-parietal DLPFC-IPS circuit engaged in temporary storage and updating of arithmetic operations. Both circuits received additional inputs from the PreCG and PreSMA playing more of a supportive role in mental calculation. The high AC group compared to the low AC group displayed a greater activation in the right IPS and based its calculation more on a feedback driven intraparietal IPS-IPS circuit, whereas the low competence group more on a feedback driven fronto-parietal DLPFC-IPS circuit. This study provides first evidence that multivariate GCM is a sensitive approach to investigate effective connectivity of mental processes involved in mental calculation and to compare group level performances for different populations. Hum Brain Mapp, 2010. © 2010 Wiley-Liss, Inc.

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