title: Transcallosal connectivity of the human cortical motor network.
abstract: The organisational and architectural configuration of white matter pathways connecting brain regions has ramifications for all facets of the human condition, including manifestations of incipient neurodegeneration. Although diffusion tensor imaging (DTI) has been used extensively to visualise white matter connectivity, due to the widespread presence of crossing fibres, the lateral projections of the corpus callosum are not normally detected using this methodology. Detailed knowledge of the transcallosal connectivity of the human cortical motor network has, therefore, remained elusive. We employed constrained spherical deconvolution (CSD) tractography-an approach that is much less susceptible to the influence of crossing fibres, in order to derive complete in vivo characterizations of white matter pathways connecting specific motor cortical regions to their counterparts and other loci in the opposite hemisphere. The revealed patterns of connectivity closely resemble those derived from anatomical tracing in primates. It was established that dorsal premotor cortex (PMd) and supplementary motor area (SMA) have extensive interhemispheric connectivity-exhibiting both dense homologous projections, and widespread structural relations with every other region in the contralateral motor network. Through this in vivo portrayal, the importance of non-primary motor regions for interhemispheric communication is emphasised. Additionally, distinct connectivity profiles were detected for the anterior and posterior subdivisions of primary motor cortex. The present findings provide a comprehensive representation of transcallosal white matter projections in humans, and have the potential to inform the development of models and hypotheses relating structural and functional brain connectivity.
authors.affiliation: School of Psychology, Queen's University Belfast, Belfast, BT7 1NN, UK. kathy.ruddy@hest.ethz.ch.|Trinity College Institute of Neuroscience and School of Psychology, Trinity College Dublin, Dublin, Ireland. kathy.ruddy@hest.ethz.ch.|Neural Control of Movement Lab, Department of Health Sciences and Technology, ETH Zurich, Y36 M 12, Winterthurerstrasse 190, 8057, Zurich, Switzerland. kathy.ruddy@hest.ethz.ch.
authors.forename: Kathy L
authors.initials: KL
authors.lastname: Ruddy
authors.affiliation: Image Sciences Institute, University Medical Center Utrecht, 85500, Utrecht, The Netherlands.
authors.forename: Alexander
authors.initials: A
authors.lastname: Leemans
authors.affiliation: School of Psychology, Queen's University Belfast, Belfast, BT7 1NN, UK.|Trinity College Institute of Neuroscience and School of Psychology, Trinity College Dublin, Dublin, Ireland.
authors.forename: Richard G
authors.initials: RG
authors.lastname: Carson
mesh_terms: D000328:Adult; D001931:Brain Mapping; D003337:Corpus Callosum / Q000000981:diagnostic imaging / Q000502:physiology*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016013:Likelihood Functions; D008297:Male; D009044:Motor Cortex / Q000000981:diagnostic imaging / Q000502:physiology*; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation; D055815:Young Adult
keywords: Constrained Spherical deconvolution; Corpus callosum; Dorsal premotor cortex; Motor cortex; Primary motor cortex; Structural connectivity; Supplementary motor area; Transcallosal; White matter