title: Dynamics of White Matter Plasticity Underlying Working Memory Training: Multimodal Evidence from Diffusion MRI and Relaxometry.
abstract: Adaptive working memory (WM) training may lead to cognitive benefits that are associated with white matter plasticity in parietofrontal networks, but the underlying mechanisms remain poorly understood. We investigated white matter microstructural changes after adaptive WM training relative to a nonadaptive comparison group. Microstructural changes were studied in the superior longitudinal fasciculus, the main parietofrontal connection, and the cingulum bundle as a comparison pathway. MRI-based metrics were the myelin water fraction and longitudinal relaxation rate R1from multicomponent relaxometry (captured with the mcDESPOT approach) as proxy metrics of myelin, the restricted volume fraction from the composite hindered and restricted model of diffusion as an estimate of axon morphology, and fractional anisotropy and radial diffusivity from diffusion tensor imaging. PCA was used for dimensionality reduction. Adaptive training was associated with benefits in a "WM capacity" component and increases in a microstructural component (increases in R1, restricted volume fraction, fractional anisotropy, and reduced radial diffusivity) that predominantly loaded on changes in the right dorsolateral superior longitudinal fasciculus and the left parahippocampal cingulum. In contrast, nonadaptive comparison activities were associated with the opposite pattern of reductions in WM capacity and microstructure. No group differences were observed for the myelin water fraction metric suggesting that R1was a more sensitive "myelin" index. These results demonstrate task complexity and location-specific white matter microstructural changes that are consistent with tissue alterations underlying myelination in response to training.
authors.affiliation: Cardiff University, Brain Research Imaging Centre (CUBRIC).
authors.forename: Claudia
authors.initials: C
authors.lastname: Metzler-Baddeley
authors.affiliation: Cardiff University, Brain Research Imaging Centre (CUBRIC).
authors.forename: Sonya
authors.initials: S
authors.lastname: Foley
authors.affiliation: University Miguel Hernandez, Alicante, Spain.
authors.forename: Silvia
authors.initials: S
authors.lastname: de Santis
authors.affiliation: Cardiff University, Brain Research Imaging Centre (CUBRIC).
authors.forename: Cyril
authors.initials: C
authors.lastname: Charron
authors.affiliation: Imperial College London.
authors.forename: Adam
authors.initials: A
authors.lastname: Hampshire
authors.affiliation: Australian Catholic University.
authors.forename: Karen
authors.initials: K
authors.lastname: Caeyenberghs
authors.affiliation: Cardiff University, Brain Research Imaging Centre (CUBRIC).|Australian Catholic University.
authors.forename: Derek K
authors.initials: DK
authors.lastname: Jones
mesh_terms: D000328:Adult; D016880:Anisotropy; D001921:Brain / Q000000981:diagnostic imaging; D003071:Cognition / Q000502:physiology*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007858:Learning / Q000502:physiology*; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009483:Neuropsychological Tests; D014706:Verbal Learning; D066127:White Matter / Q000000981:diagnostic imaging*; D055815:Young Adult