title: White matter connections of the supplementary motor area in humans.
abstract: BACKGROUND
  The supplementary motor area (SMA) is frequently involved by brain tumours (particularly WHO grade II gliomas). Surgery in this area can be followed by the 'SMA syndrome', characterised by contralateral akinesia and mutism. Knowledge of the connections of the SMA can provide new insights on the genesis of the SMA syndrome, and a better understanding of the challenges related to operating in this region.
  
  
  METHODS
  White matter connections of the SMA were studied with both postmortem dissection and advance diffusion imaging tractography. Postmortem dissections were performed according to the Klingler technique. 12 specimens were fixed in 10% formalin and frozen at -15°C for 2 weeks. After thawing, dissection was performed with blunt dissectors. For diffusion tractography, high-resolution diffusion imaging datasets from 10 adult healthy controls from the Human Connectome Project database were used. Whole brain tractography was performed using a spherical deconvolution approach.
  
  
  RESULTS
  Five main connections were identified in both postmortem dissections and tractography reconstructions: (1) U-fibres running in the precentral sulcus, connecting the precentral gyrus and the SMA; (2) U-fibres running in the cingulate sulcus, connecting the SMA with the cingulate gyrus; (3) frontal 'aslant' fascicle, directly connecting the SMA with the pars opercularis of the inferior frontal gyrus; (4) medial fibres connecting the SMA with the striatum; and (5) SMA callosal fibres. Good concordance was observed between postmortem dissections and diffusion tractography.
  
  
  CONCLUSIONS
  The SMA shows a wide range of white matter connections with motor, language and lymbic areas. Features of the SMA syndrome (akinesia and mutism) can be better understood on the basis of these findings.
authors.affiliation: Department of Neurosurgery, Royal Victoria Infirmary, Newcastle upon Tyne, UK Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Francesco
authors.initials: F
authors.lastname: Vergani
authors.affiliation: Natbrainlab, Department of Neuroimaging, Institute of Psychiatry, King's College London, London, UK.
authors.forename: Luis
authors.initials: L
authors.lastname: Lacerda
authors.affiliation: Department of Neurological Surgery, Hospital Universitario Marqués de Valdecilla and Instituto de Formación e Investigación Marqués de Valdecilla (IFIMAV), Santander, Cantabria, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Martino
authors.affiliation: Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Johannes
authors.initials: J
authors.lastname: Attems
authors.affiliation: Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK Medical Toxicology Centre, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Christopher
authors.initials: C
authors.lastname: Morris
authors.affiliation: Department of Neurosurgery, Royal Victoria Infirmary, Newcastle upon Tyne, UK Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Patrick
authors.initials: P
authors.lastname: Mitchell
authors.affiliation: Natbrainlab, Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, King's College London, London, UK Université Pierre et Marie Curie-Paris 6, Centre de Recherche de l'Institut du Cerveau et de la Moelle épinière (CRICM), UMRS 975, INSERM U 975, CNRS UMR, Paris, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Thiebaut de Schotten
authors.affiliation: Natbrainlab, Department of Neuroimaging, Institute of Psychiatry, King's College London, London, UK NIHR Biomedical Research Centre for Mental Health at South London and Maudsley NHS Foundation Trust and King's College London, Institute of Psychiatry, London, UK.
authors.forename: Flavio
authors.initials: F
authors.lastname: Dell'Acqua
mesh_terms: D000328:Adult; D063132:Connectome; D056324:Diffusion Tensor Imaging; D006801:Humans; D008032:Limbic System / Q000033:anatomy & histology / Q000502:physiology; D009044:Motor Cortex / Q000033:anatomy & histology* / Q000502:physiology; D009068:Movement / Q000502:physiology; D009434:Neural Pathways / Q000033:anatomy & histology* / Q000502:physiology; D013060:Speech / Q000502:physiology; D066127:White Matter / Q000033:anatomy & histology* / Q000502:physiology