title: Diagnosing developmental dyscalculia on the basis of reliable single case FMRI methods: promises and limitations.
abstract: FMRI-studies are mostly based on a group study approach, either analyzing one group or comparing multiple groups, or on approaches that correlate brain activation with clinically relevant criteria or behavioral measures. In this study we investigate the potential of fMRI-techniques focusing on individual differences in brain activation within a test-retest reliability context. We employ a single-case analysis approach, which contrasts dyscalculic children with a control group of typically developing children. In a second step, a support-vector machine analysis and cluster analysis techniques served to investigate similarities in multivariate brain activation patterns. Children were confronted with a non-symbolic number comparison and a non-symbolic exact calculation task during fMRI acquisition. Conventional second level group comparison analysis only showed small differences around the angular gyrus bilaterally and the left parieto-occipital sulcus. Analyses based on single-case statistical procedures revealed that developmental dyscalculia is characterized by individual differences predominantly in visual processing areas. Dyscalculic children seemed to compensate for relative under-activation in the primary visual cortex through an upregulation in higher visual areas. However, overlap in deviant activation was low for the dyscalculic children, indicating that developmental dyscalculia is a disorder characterized by heterogeneous brain activation differences. Using support vector machine analysis and cluster analysis, we tried to group dyscalculic and typically developing children according to brain activation. Fronto-parietal systems seem to qualify for a distinction between the two groups. However, this was only effective when reliable brain activations of both tasks were employed simultaneously. Results suggest that deficits in number representation in the visual-parietal cortex get compensated for through finger related aspects of number representation in fronto-parietal cortex. We conclude that dyscalculic children show large individual differences in brain activation patterns. Nonetheless, the majority of dyscalculic children can be differentiated from controls employing brain activation patterns when appropriate methods are used.
authors.affiliation: Interdisciplinary Center of Clinical Research "BIOMAT", University Hospital of the RWTH, Aachen, Germany.
authors.forename: Philipp Johannes
authors.initials: PJ
authors.lastname: Dinkel
authors.affiliation: Interdisciplinary Center of Clinical Research "BIOMAT", University Hospital of the RWTH, Aachen, Germany ; Section Neuropsychology, Department of Neurology, University Hospital of the RWTH, Aachen, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Willmes
authors.affiliation: Section Child Neuropsychology, Department of Child and Adolescent Psychiatry, University Hospital of the RWTH, Aachen, Germany.
authors.forename: Helga
authors.initials: H
authors.lastname: Krinzinger
authors.affiliation: Section Child Neuropsychology, Department of Child and Adolescent Psychiatry, University Hospital of the RWTH, Aachen, Germany ; Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-III), Research Centre Jülich, Jülich, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Konrad
authors.affiliation: Section Neuropsychology, Department of Neurology, University Hospital of the RWTH, Aachen, Germany.
authors.forename: Jan Willem
authors.initials: JW
authors.lastname: Koten
mesh_terms: D002648:Child; D060705:Dyscalculia / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010296:Parietal Lobe / Q000000981:diagnostic imaging / Q000503:physiopathology; D011859:Radiography; D014793:Visual Cortex / Q000000981:diagnostic imaging / Q000503:physiopathology; D014796:Visual Perception