title: Different Roles of Direct and Indirect Frontoparietal Pathways for Individual Working Memory Capacity.
abstract: The ability to temporarily store and manipulate information in working memory is a hallmark of human intelligence and differs considerably across individuals, but the structural brain correlates underlying these differences in working memory capacity (WMC) are only poorly understood. In two separate studies, diffusion MRI data and WMC scores were collected for 70 and 109 healthy individuals. Using a combination of probabilistic tractography and network analysis of the white matter tracts, we examined whether structural brain network properties were predictive of individual WMC. Converging evidence from both studies showed that lateral prefrontal cortex and posterior parietal cortex of high-capacity individuals are more densely connected compared with low-capacity individuals. Importantly, our network approach was further able to dissociate putative functional roles associated with two different pathways connecting frontal and parietal regions: a corticocortical pathway and a subcortical pathway. In Study 1, where participants were required to maintain and update working memory items, the connectivity of the direct and indirect pathway was predictive of WMC. In contrast, in Study 2, where participants were required to maintain working memory items without updating, only the connectivity of the direct pathway was predictive of individual WMC. Our results suggest an important dissociation in the circuitry connecting frontal and parietal regions, where direct frontoparietal connections might support storage and maintenance, whereas subcortically mediated connections support the flexible updating of working memory content.
authors.affiliation: Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, 6500 HE Nijmegen, The Netherlands, Max Planck Institute for Neurological Research, 50931 Cologne, Germany, matthias.ekman@gmail.com.
authors.forename: Matthias
authors.identifier: http://orcid.org/0000-0003-1254-1392
authors.initials: M
authors.lastname: Ekman
authors.affiliation: Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, 6500 HE Nijmegen, The Netherlands, Department of Psychology, Goethe University Frankfurt, 60323 Frankfurt am Main, Germany, and Center for Individual Development and Adaptive Education, 60486 Frankfurt am Main, Germany.
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Fiebach
authors.affiliation: Max Planck Institute for Neurological Research, 50931 Cologne, Germany.
authors.forename: Corina
authors.initials: C
authors.lastname: Melzer
authors.affiliation: Max Planck Institute for Neurological Research, 50931 Cologne, Germany.
authors.forename: Marc
authors.identifier: http://orcid.org/0000-0001-5072-2149
authors.initials: M
authors.lastname: Tittgemeyer
authors.affiliation: Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, 6500 HE Nijmegen, The Netherlands, Max Planck Institute for Neurological Research, 50931 Cologne, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Derrfuss
mesh_terms: D000328:Adult; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D005625:Frontal Lobe / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009434:Neural Pathways / Q000033:anatomy & histology / Q000502:physiology*; D009483:Neuropsychological Tests; D010296:Parietal Lobe / Q000033:anatomy & histology / Q000502:physiology*; D011336:Probability; D066127:White Matter / Q000033:anatomy & histology / Q000502:physiology; D055815:Young Adult
keywords: basal ganglia; diffusion MRI; network analysis; prefrontal cortex; working memory capacity