title: Reduced Volume of the Arcuate Fasciculus in Adults with High-Functioning Autism Spectrum Conditions.
abstract: Atypical language is a fundamental feature of autism spectrum conditions (ASC), but few studies have examined the structural integrity of the arcuate fasciculus, the major white matter tract connecting frontal and temporal language regions, which is usually implicated as the main transfer route used in processing linguistic information by the brain. Abnormalities in the arcuate have been reported in young children with ASC, mostly in low-functioning or non-verbal individuals, but little is known regarding the structural properties of the arcuate in adults with ASC or, in particular, in individuals with ASC who have intact language, such as those with high-functioning autism or Asperger syndrome. We used probabilistic tractography of diffusion-weighted imaging to isolate and scrutinize the arcuate in a mixed-gender sample of 18 high-functioning adults with ASC (17 Asperger syndrome) and 14 age- and IQ-matched typically developing controls. Arcuate volume was significantly reduced bilaterally with clearest differences in the right hemisphere. This finding remained significant in an analysis of all male participants alone. Volumetric reduction in the arcuate was significantly correlated with the severity of autistic symptoms as measured by the Autism-Spectrum Quotient. These data reveal that structural differences are present even in high-functioning adults with ASC, who presented with no clinically manifest language deficits and had no reported developmental language delay. Arcuate structural integrity may be useful as an index of ASC severity and thus as a predictor and biomarker for ASC. Implications for future research are discussed.
authors.affiliation: Department of Psychology, Bournemouth UniversityDorset, UK; Medical Research Council Cognition and Brain Sciences UnitCambridge, UK; Brain Mapping Unit, Department of Psychiatry, University of CambridgeCambridge, UK; Autism Research Centre, Department of Psychiatry, University of CambridgeCambridge, UK.
authors.forename: Rachel L
authors.initials: RL
authors.lastname: Moseley
authors.affiliation: Medical Research Council Cognition and Brain Sciences Unit Cambridge, UK.
authors.forename: Marta M
authors.initials: MM
authors.lastname: Correia
authors.affiliation: Autism Research Centre, Department of Psychiatry, University of CambridgeCambridge, UK; Cambridge Lifespan Asperger Syndrome Service Clinic, Cambridgeshire and Peterborough National Health Service Foundation TrustCambridge, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Baron-Cohen
authors.affiliation: Medical Research Council Cognition and Brain Sciences UnitCambridge, UK; Center of Functionally Integrative Neuroscience (CFIN), Department of Clinical Medicine, Aarhus UniversityAarhus, Denmark; Centre for Cognition and Decision Making, National Research University Higher School of EconomicsMoscow, Russia.
authors.forename: Yury
authors.initials: Y
authors.lastname: Shtyrov
authors.affiliation: Medical Research Council Cognition and Brain Sciences UnitCambridge, UK; Brain Language Laboratory, Freie Universität BerlinBerlin, Germany.
authors.forename: Friedemann
authors.initials: F
authors.lastname: Pulvermüller
authors.affiliation: Department of Psychiatry, Charité-Universitätsmedizin Berlin Berlin, Germany.
authors.forename: Bettina
authors.initials: B
authors.lastname: Mohr
keywords: Asperger syndrome; arcuate fasciculus; autism; diffusion-weighted imaging (DWI); language