title: Alterations in brain white matter contributing to age-related slowing of task switching performance: The role of radial diffusivity and magnetization transfer ratio.
abstract: Successfully switching between tasks is critical in many daily activities. Age-related slowing of this switching behavior has been documented extensively, but the underlying neural mechanisms remain unclear. Here, we investigated the contribution of brain white matter changes associated with myelin alterations to age-related slowing of switching performance. Diffusion tensor imaging derived radial diffusivity (RD) and magnetization transfer imaging derived magnetization transfer ratio (MTR) were selected as myelin sensitive measures. These metrics were studied in relation to mixing cost (i.e., the increase in reaction time during task blocks that require task switching) on a local-global switching task in young (n = 24) and older (n = 22) adults. Results showed that higher age was associated with widespread increases in RD and decreases in MTR, indicative of white matter deterioration, possibly due to demyelination. Older adults also showed a higher mixing cost, implying slowing of switching performance. Finally, mediation analyses demonstrated that decreases in MTR of the bilateral superior corona radiata contributed to the observed slowing of switching performance with increasing age. These findings provide evidence for a role of cortico-subcortical white matter changes in task switching performance deterioration with healthy aging. Hum Brain Mapp 37:4084-4098, 2016. © 2016 Wiley Periodicals, Inc.
authors: Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium.
authors: Leen
authors: L
authors: Serbruyns
authors: Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium.
authors: Inge
authors: I
authors: Leunissen
authors: Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium.
authors: Peter
authors: P
authors: van Ruitenbeek
authors: Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium.
authors: Lisa
authors: L
authors: Pauwels
authors: Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium.|School of Psychology, Faculty of Health Sciences, Australian Catholic University, Australia.
authors: Karen
authors: K
authors: Caeyenberghs
authors: Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium.
authors: Elena
authors: E
authors: Solesio-Jofre
authors: Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium.
authors: Monique
authors: M
authors: Geurts
authors: Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium.|REVAL Rehabilitation Research Centre, Biomedical Research Institute, Faculty of Medicine and Life Sciences, Hasselt University, Diepenbeek, Belgium.
authors: Koen
authors: K
authors: Cuypers
authors: Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium.|REVAL Rehabilitation Research Centre, Biomedical Research Institute, Faculty of Medicine and Life Sciences, Hasselt University, Diepenbeek, Belgium.
authors: Raf L
authors: RL
authors: Meesen
authors: Medical Imaging Research Center, Group Biomedical Sciences, KU Leuven, Leuven, Belgium.
authors: Stefan
authors: S
authors: Sunaert
authors: Image Sciences Institute, University Medical Center Utrecht, The Netherlands.
authors: Alexander
authors: A
authors: Leemans
authors: Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, Group Biomedical Sciences, KU Leuven, Leuven, Belgium. Stephan.Swinnen@faber.kuleuven.be.|KU Leuven, Leuven Research Institute for Neuroscience & Disease (LIND), Belgium. Stephan.Swinnen@faber.kuleuven.be.
authors: Stephan P
authors: SP
authors: Swinnen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology* / Q000523:psychology*; D001921:Brain / Q000000981:diagnostic imaging*; D056324:Diffusion Tensor Imaging; D056344:Executive Function / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011930:Reaction Time / Q000502:physiology; D066127:White Matter / Q000000981:diagnostic imaging*; D055815:Young Adult
keywords: aging; diffusion tensor imaging; magnetization transfer imaging; mediation; mixing cost; switch cost