title: LEFT VERSUS RIGHT HEMISPHERE DIFFERENCES IN BRAIN CONNECTIVITY: 4-TESLA HARDI TRACTOGRAPHY IN 569 TWINS.
abstract: Diffusion imaging can map anatomical connectivity in the living brain, offering new insights into fundamental questions such as how the left and right brain hemispheres differ. Anatomical brain asymmetries are related to speech and language abilities, but less is known about left/right hemisphere differences in brain wiring. To assess this, we scanned 457 young adults (age 23.4±2.0 SD years) and 112 adolescents (age 12-16) with 4-Tesla 105-gradient high-angular resolution diffusion imaging. We extracted fiber tracts throughout the brain with a Hough transform method. A 70×70 connectivity matrix was created, for each subject, based on the proportion of fibers intersecting 70 cortical regions. We identified significant differences in the proportions of fibers intersecting left and right hemisphere cortical regions. The degree of asymmetry in the connectivity matrices varied with age, as did the asymmetry in network topology measures such as the small-world effect.
authors.affiliation: Laboratory of Neuro Imaging, Department of Neurology, UCLA School of Medicine, Los Angeles, CA.
authors.forename: Madelaine
authors.initials: M
authors.lastname: Daianu
authors.affiliation: Laboratory of Neuro Imaging, Department of Neurology, UCLA School of Medicine, Los Angeles, CA.
authors.forename: Neda
authors.initials: N
authors.lastname: Jahanshad
authors.affiliation: Laboratory of Neuro Imaging, Department of Neurology, UCLA School of Medicine, Los Angeles, CA.
authors.forename: Emily L
authors.initials: EL
authors.lastname: Dennis
authors.affiliation: Laboratory of Neuro Imaging, Department of Neurology, UCLA School of Medicine, Los Angeles, CA.
authors.forename: Arthur W
authors.initials: AW
authors.lastname: Toga
authors.affiliation: Centre for Advanced Imaging, University of Queensland, Brisbane, Australia.
authors.forename: Katie L
authors.initials: KL
authors.lastname: McMahon
authors.affiliation: School of Psychology, University of Queensland, Brisbane, Australia.
authors.forename: Greig I
authors.initials: GI
authors.lastname: de Zubicaray
authors.affiliation: Queensland Institute of Medical Research, Brisbane, Australia.
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Martin
authors.affiliation: Centre for Advanced Imaging, University of Queensland, Brisbane, Australia ; Queensland Institute of Medical Research, Brisbane, Australia.
authors.forename: Margaret J
authors.initials: MJ
authors.lastname: Wright
authors.affiliation: University of Sydney, Brain and Mind Research Institute, Australia.
authors.forename: Ian B
authors.initials: IB
authors.lastname: Hickie
authors.affiliation: Laboratory of Neuro Imaging, Department of Neurology, UCLA School of Medicine, Los Angeles, CA.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Thompson
keywords: connectome; high angular resolution diffusion imaging (HARDI); laterality; small-world effect; tractography