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Research paper
White matter connections of the supplementary motor area in humans
  1. Francesco Vergani1,2,
  2. Luis Lacerda3,
  3. Juan Martino4,
  4. Johannes Attems5,
  5. Christopher Morris2,6,
  6. Patrick Mitchell1,2,
  7. Michel Thiebaut de Schotten7,8,
  8. Flavio Dell'Acqua3,9
  1. 1Department of Neurosurgery, Royal Victoria Infirmary, Newcastle upon Tyne, UK
  2. 2Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
  3. 3Natbrainlab, Department of Neuroimaging, Institute of Psychiatry, King's College London, London, UK
  4. 4Department of Neurological Surgery, Hospital Universitario Marqués de Valdecilla and Instituto de Formación e Investigación Marqués de Valdecilla (IFIMAV), Santander, Cantabria, Spain
  5. 5Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, UK
  6. 6Medical Toxicology Centre, Newcastle University, Newcastle upon Tyne, UK
  7. 7Natbrainlab, Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, King's College London, London, UK
  8. 8Université 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
  9. 9NIHR Biomedical Research Centre for Mental Health at South London and Maudsley NHS Foundation Trust and King's College London, Institute of Psychiatry, London, UK
  1. Correspondence to Dr Francesco Vergani, Department of Neurosurgery, Regional Neurosciences Centre, Royal Victoria Infirmary, Queen Victoria road, Newcastle upon Tyne NE1 4LP, UK; francesco.vergani{at}


Introduction 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.

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