title: Relations between white matter maturation and reaction time in childhood.
abstract: White matter matures with age and is important for the efficient transmission of neuronal signals. Consequently, white matter growth may underlie the development of cognitive processes important for learning, including the speed of information processing. To dissect the relationship between white matter structure and information processing speed, we administered a reaction time task (finger abduction in response to visual cue) to 27 typically developing, right-handed children aged 4 to 13. Magnetoencephalography and Diffusion Tensor Imaging were used to delineate white matter connections implicated in visual-motor information processing. Fractional anisotropy (FA) and radial diffusivity (RD) of the optic radiation in the left hemisphere, and FA and mean diffusivity (MD) of the optic radiation in the right hemisphere changed significantly with age. MD and RD decreased with age in the right inferior fronto-occipital fasciculus, and bilaterally in the cortico-spinal tracts. No age-related changes were evident in the inferior longitudinal fasciculus. FA of the cortico-spinal tract in the left hemisphere and MD of the inferior fronto-occipital fasciculus of the right hemisphere contributed uniquely beyond the effect of age in accounting for reaction time performance of the right hand. Our findings support the role of white matter maturation in the development of information processing speed.
authors.affiliation: 1 Brain and Behavior Program, The Hospital for Sick Children, Toronto, Ontario.
authors.forename: Nadia
authors.initials: N
authors.lastname: Scantlebury
authors.affiliation: 1 Brain and Behavior Program, The Hospital for Sick Children, Toronto, Ontario.
authors.forename: Todd
authors.initials: T
authors.lastname: Cunningham
authors.affiliation: 1 Brain and Behavior Program, The Hospital for Sick Children, Toronto, Ontario.
authors.forename: Colleen
authors.initials: C
authors.lastname: Dockstader
authors.affiliation: 2 Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Laughlin
authors.affiliation: 4 Department of Radiology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: William
authors.initials: W
authors.lastname: Gaetz
authors.affiliation: 5 Department of Biomedical Engineering, McMaster University, Hamilton, Ontario.
authors.forename: Conrad
authors.initials: C
authors.lastname: Rockel
authors.affiliation: 1 Brain and Behavior Program, The Hospital for Sick Children, Toronto, Ontario.
authors.forename: Jolynn
authors.initials: J
authors.lastname: Dickson
authors.affiliation: 1 Brain and Behavior Program, The Hospital for Sick Children, Toronto, Ontario.
authors.forename: Donald
authors.initials: D
authors.lastname: Mabbott
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology*; D066127:White Matter / Q000254:growth & development*