title: Delayed convergence between brain network structure and function in rolandic epilepsy.
abstract: BACKGROUND
  Rolandic epilepsy (RE) manifests during a critical phase of brain development, and has been associated with language impairments. Concordant abnormalities in structural and functional connectivity (SC and FC) have been described before. As SC and FC are under mutual influence, the current study investigates abnormalities in the SC-FC synergy in RE.
  
  
  METHODS
  Twenty-two children with RE (age, mean ± SD: 11.3 ± 2.0 y) and 22 healthy controls (age 10.5 ± 1.6 y) underwent structural, diffusion weighted, and resting-state functional magnetic resonance imaging (MRI) at 3T. The probabilistic anatomical landmarks atlas was used to parcellate the (sub)cortical gray matter. Constrained spherical deconvolution tractography and correlation of time series were used to assess SC and FC, respectively. The SC-FC correlation was assessed as a function of age for the non-zero structural connections over a range of sparsity values (0.01-0.75). A modularity analysis was performed on the mean SC network of the controls to localize potential global effects to subnetworks. SC and FC were also assessed separately using graph analysis.
  
  
  RESULTS
  The SC-FC correlation was significantly reduced in children with RE compared to healthy controls, especially for the youngest participants. This effect was most pronounced in a left and a right centro-temporal network, as well as in a medial parietal network. Graph analysis revealed no prominent abnormalities in SC or FC network organization.
  
  
  CONCLUSIONS
  Since SC and FC converge during normal maturation, our finding of reduced SC-FC correlation illustrates impaired synergy between brain structure and function. More specifically, since this effect was most pronounced in the youngest participants, RE may represent a developmental disorder of delayed brain network maturation. The observed effects seem especially attributable to medial parietal connections, which forms an intermediate between bilateral centro-temporal modules of epileptiform activity, and bear relevance for language function.
authors.affiliation: Epilepsy Center Kempenhaeghe Heeze, Netherlands ; Research School for Mental Health and Neuroscience, Maastricht University Maastricht, Netherlands ; Department of Radiology, Maastricht University Medical Center Maastricht, Netherlands.
authors.forename: René M H
authors.initials: RM
authors.lastname: Besseling
authors.affiliation: Research School for Mental Health and Neuroscience, Maastricht University Maastricht, Netherlands ; Department of Radiology, Maastricht University Medical Center Maastricht, Netherlands.
authors.forename: Jacobus F A
authors.initials: JF
authors.lastname: Jansen
authors.affiliation: Epilepsy Center Kempenhaeghe Heeze, Netherlands ; Department of Neurology, Maastricht University Medical Center Maastricht, Netherlands.
authors.forename: Geke M
authors.initials: GM
authors.lastname: Overvliet
authors.affiliation: Epilepsy Center Kempenhaeghe Heeze, Netherlands ; Research School for Mental Health and Neuroscience, Maastricht University Maastricht, Netherlands.
authors.forename: Sylvie J M
authors.initials: SJ
authors.lastname: van der Kruijs
authors.affiliation: Epilepsy Center Kempenhaeghe Heeze, Netherlands.
authors.forename: Saskia C M
authors.initials: SC
authors.lastname: Ebus
authors.affiliation: Epilepsy Center Kempenhaeghe Heeze, Netherlands ; Department of Neurology, Maastricht University Medical Center Maastricht, Netherlands.
authors.forename: Anton J A
authors.initials: AJ
authors.lastname: de Louw
authors.affiliation: Epilepsy Center Kempenhaeghe Heeze, Netherlands ; Department of Neurology, Maastricht University Medical Center Maastricht, Netherlands.
authors.forename: Paul A M
authors.initials: PA
authors.lastname: Hofman
authors.affiliation: Epilepsy Center Kempenhaeghe Heeze, Netherlands ; Department of Neurology, Maastricht University Medical Center Maastricht, Netherlands.
authors.forename: Albert P
authors.initials: AP
authors.lastname: Aldenkamp
authors.affiliation: Research School for Mental Health and Neuroscience, Maastricht University Maastricht, Netherlands ; Department of Radiology, Maastricht University Medical Center Maastricht, Netherlands.
authors.forename: Walter H
authors.initials: WH
authors.lastname: Backes
keywords: brain maturation; functional connectivity; graph theory; rolandic epilepsy; structural connectivity; structure-function correlation