title: Impaired Communication Between the Motor and Somatosensory Homunculus Is Associated With Poor Manual Dexterity in Autism Spectrum Disorder.
abstract: Fine motor skill impairments are common in autism spectrum disorder (ASD), significantly affecting quality of life. Sensory inputs reaching the primary motor cortex (M1) from the somatosensory cortex (S1) are likely involved in fine motor skill and specifically motor learning. However, the role of these connections has not been directly investigated in humans. This study aimed to investigate, for the first time, the role of the S1-M1 connections in healthy subjects in vivo and whether microstructural alterations are associated with motor impairment in ASD.
  
  
  
  Sixty right-handed neurotypical adult men aged 18 to 45 years, and 60 right-handed age- and sex-matched subjects diagnosed with ASD underwent fine motor skill assessment and scanning with diffusion tensor imaging (DTI). The streamlines of the hand region connecting S1-M1 of the motor-sensory homunculus were virtually dissected using TrackVis, and diffusion properties were extracted. The face/tongue region connections were used as control tracts.
  
  
  
  The ASD group displayed lower motor performances and altered DTI measurements of the hand-region connection. Behavioral performance correlated with hand-region DTI measures in both groups, but not with the face/tongue connections, indicating anatomical specificity. There was a left-hemisphere association of motor ability in the control group and an atypical rightward shift in the ASD group.
  
  
  
  These findings suggest that direct interaction between S1 and M1 may contribute to the human ability to precisely interact with and manipulate the environment. Because electrophysiological evidence indicates that these connections may underpin long-term potentiation in M1, our findings may lead to novel therapeutic treatments for motor skill disorders.
authors.affiliation: NatBrainLab, Department of Forensic, and the Sackler Institute for Translational Neurodevelopmental Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London. Electronic address: abigail.thompson@kcl.ac.uk.
authors.forename: Abigail
authors.initials: A
authors.lastname: Thompson
authors.affiliation: Neurodevelopmental Sciences, and the Sackler Institute for Translational Neurodevelopmental Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London.
authors.forename: Declan
authors.initials: D
authors.lastname: Murphy
authors.affiliation: Department of Neuroimaging, and the Sackler Institute for Translational Neurodevelopmental Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London.
authors.forename: Flavio
authors.initials: F
authors.lastname: Dell'Acqua
authors.affiliation: Neurodevelopmental Sciences, and the Sackler Institute for Translational Neurodevelopmental Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London.
authors.forename: Christine
authors.initials: C
authors.lastname: Ecker
authors.affiliation: Neurodevelopmental Sciences, and the Sackler Institute for Translational Neurodevelopmental Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London.
authors.forename: Grainne
authors.initials: G
authors.lastname: McAlonan
authors.affiliation: NatBrainLab, Department of Forensic, and the Sackler Institute for Translational Neurodevelopmental Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London.
authors.forename: Henrietta
authors.initials: H
authors.lastname: Howells
authors.affiliation: Autism Research Centre, Department of Psychiatry, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Simon
authors.initials: S
authors.lastname: Baron-Cohen
authors.affiliation: NatBrainLab, Department of Forensic, and the Sackler Institute for Translational Neurodevelopmental Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London; Autism Research Centre, Department of Psychiatry, University of Cambridge, Cambridge, United Kingdom; Child and Youth Mental Health Collaborative at the Centre for Addiction and Mental Health and The Hospital for Sick Children, and Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada; Department of Psychiatry, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan.
authors.forename: Meng-Chuan
authors.initials: MC
authors.lastname: Lai
authors.affiliation: Autism Research Centre, Department of Psychiatry, University of Cambridge, Cambridge, United Kingdom; Department of Psychology and, University of Cyprus, Nicosia, Cyprus; Center for Applied Neuroscience, University of Cyprus, Nicosia, Cyprus.
authors.forename: Michael V
authors.initials: MV
authors.lastname: Lombardo
mesh_terms: D000293:Adolescent; D000328:Adult; D000067877:Autism Spectrum Disorder / Q000473:pathology / Q000503:physiopathology*; D056324:Diffusion Tensor Imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000473:pathology / Q000503:physiopathology*; D009048:Motor Skills; D009434:Neural Pathways / Q000502:physiology / Q000503:physiopathology*; D013003:Somatosensory Cortex / Q000473:pathology / Q000503:physiopathology*; D055815:Young Adult
keywords: Autism; Diffusion tensor imaging; Homunculus; Motor skill; Primary motor cortex; Somatosensory cortex; Tractography