title: An electrophysiological investigation of non-symbolic magnitude processing: numerical distance effects in children with and without mathematical learning disabilities.
abstract: BACKGROUND
  The aim of the present study was to probe electrophysiological effects of non-symbolic numerical processing in 20 children with mathematical learning disabilities (mean age = 99.2 months) compared to a group of 20 typically developing matched controls (mean age = 98.4 months).
  
  
  METHODS
  EEG data were obtained while children were tested with a standard non-symbolic numerical comparison paradigm that allowed us to investigate the effects of numerical distance manipulations for different set sizes, i.e., the classical subitizing, counting and estimation ranges. Effects of numerical distance manipulations on event-related potential (ERP) amplitudes as well as activation patterns of underlying current sources were analyzed.
  
  
  RESULTS
  In typically developing children, the amplitudes of a late parietal positive-going ERP component showed systematic numerical distance effects that did not depend on set size. For the group of children with mathematical learning disabilities, ERP distance effects were found only for stimuli within the subitizing range. Current source density analysis of distance-related group effects suggested that areas in right inferior parietal regions are involved in the generation of the parietal ERP amplitude differences.
  
  
  CONCLUSIONS
  Our results suggest that right inferior parietal regions are recruited differentially by controls compared to children with mathematical learning disabilities in response to non-symbolic numerical magnitude processing tasks, but only for stimuli with set sizes that exceed the subitizing range.
authors.affiliation: Department of Psychology, Freie Universität Berlin, Germany. aheine@zedat.fu-berlin.de
authors.forename: Angela
authors.initials: A
authors.lastname: Heine
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Wissmann
authors.forename: Sascha
authors.initials: S
authors.lastname: Tamm
authors.forename: Bert
authors.initials: B
authors.lastname: De Smedt
authors.forename: Michael
authors.initials: M
authors.lastname: Schneider
authors.forename: Elsbeth
authors.initials: E
authors.lastname: Stern
authors.forename: Lieven
authors.initials: L
authors.lastname: Verschaffel
authors.forename: Arthur M
authors.initials: AM
authors.lastname: Jacobs
mesh_terms: D001921:Brain / Q000502:physiology / Q000503:physiopathology*; D001931:Brain Mapping; D016022:Case-Control Studies; D002648:Child; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D007859:Learning Disabilities / Q000503:physiopathology*; D008297:Male; D008433:Mathematics; D010296:Parietal Lobe / Q000502:physiology / Q000503:physiopathology
keywords: Children; EEG; Mathematical learning disabilities; Non-symbolic numerical comparison; Numerical distance effect