title: Microstructural asymmetry of the corticospinal tracts predicts right-left differences in circle drawing skill in right-handed adolescents.
abstract: Most humans show a strong preference to use their right hand, but strong preference for the right hand does not necessarily imply a strong right-left asymmetry in manual proficiency (i.e., dexterity). Here we tested the hypothesis that intra-individual asymmetry of manual proficiency would be reflected in microstructural differences between the right and left corticospinal tract (CST) in a cohort of 52 right-handed typically-developing adolescents (11-16 years). Participants were asked to fluently draw superimposed circles with their right dominant and left non-dominant hand. Temporal regularity of circle drawing movements was assessed for each hand using a digitizing tablet. Although all participants were right-handed, there was substantial inter-individual variation regarding the relative right-hand advantage for fluent circle drawing. All subjects underwent whole-brain diffusion tensor imaging at 3 Tesla. The right and left CST were defined as regions-of-interest and mean fractional anisotropy (FA) and diffusivity values were calculated for right and left CST. On average, mean FA values were higher in the left CST relative to right CST. The degree of right-left FA asymmetry showed a linear relationship with right-left asymmetry in fluent circle drawing after correction for age and gender. The higher the mean FA values were in the left dominant CST relative to the right non-dominant CST, the stronger was the relative right-hand advantage for regular circle drawing. These findings show that right-left differences in manual proficiency are highly variable in right-handed adolescents and that this variation is associated with a right-left microstructural asymmetry of the CST.
authors.affiliation: Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, 2650, Hvidovre, Denmark. steffena@drcmr.dk.
authors.forename: Steffen
authors.identifier: 0000-0003-0709-0267
authors.initials: S
authors.lastname: Angstmann
authors.affiliation: Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, 2650, Hvidovre, Denmark.
authors.forename: Kathrine Skak
authors.initials: KS
authors.lastname: Madsen
authors.affiliation: Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, 2650, Hvidovre, Denmark.
authors.forename: Arnold
authors.initials: A
authors.lastname: Skimminge
authors.affiliation: Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, 2650, Hvidovre, Denmark.|Center for Human Development, University of California, San Diego, CA, USA.
authors.forename: Terry L
authors.initials: TL
authors.lastname: Jernigan
authors.affiliation: Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, 2650, Hvidovre, Denmark.
authors.forename: William F C
authors.initials: WF
authors.lastname: Baaré
authors.affiliation: Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, 2650, Hvidovre, Denmark.|Department of Neurology, Copenhagen University Hospital Bispebjerg, Bispebjerg, Denmark.
authors.forename: Hartwig Roman
authors.initials: HR
authors.lastname: Siebner
mesh_terms: D000293:Adolescent; D001696:Biomechanical Phenomena; D002648:Child; D038524:Diffusion Magnetic Resonance Imaging; D056324:Diffusion Tensor Imaging; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D009043:Motor Activity; D009048:Motor Skills; D011712:Pyramidal Tracts / Q000033:anatomy & histology* / Q000502:physiology
keywords: Brain development; Circle drawing; Corticospinal tract; Diffusion tensor imaging; Hemispheric asymmetry; Manual dexterity