title: Increased fractional anisotropy in the motor tracts of Parkinson's disease suggests compensatory neuroplasticity or selective neurodegeneration.
abstract: OBJECTIVE
  To determine the differences in motor pathways and selected non-motor pathways of the basal ganglia in Parkinson's disease (PD) patients compared to healthy controls (HCs).
  
  
  METHODS
  We analysed diffusion weighted imaging data of 24 PD patients and 26 HCs. We performed deterministic tractography analysis using the spherical deconvolution-based damped Richardson-Lucy algorithm and subcortical volume analysis.
  
  
  RESULTS
  We found significantly increased fractional anisotropy (FA) in the motor pathways of PD patients: the bilateral corticospinal tract (right; corrected p = 0.0003, left; corrected p = 0.03), bilateral thalamus-motor cortex tract (right; corrected p = 0.02, left; corrected p = 0.004) and the right supplementary area-putamen tract (corrected p = 0.001). We also found significantly decreased FA in the right uncinate fasiculus (corrected p = 0.01) and no differences of FA in the bilateral supero-lateral medial forebrain bundles (p > 0.05) of PD patients compared to HCs. There were no subcortical volume differences (p > 0.05) between the PD patients and HCs.
  
  
  CONCLUSIONS
  These results can inform biological models of neurodegeneration and neuroplasticity in PD. We suggest that increased FA values in the motor tracts in PD may reflect compensatory reorganization of neural circuits indicative of adaptive or extended neuroplasticity.
  
  
  CONCLUSIONS
  • Fractional anisotropy was higher in motor pathways of PD patients compared to healthy controls. • Fractional anisotropy was lower in the uncinate fasciculus of PD patients compared to healthy controls. • Increased fractional anisotropy could suggest adaptive neuroplasticity or selective neurodegeneration.
authors.affiliation: Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Cardiff, UK.|Institute of Psychological Medicine and Clinical Neurosciences (IPMCN), School of Medicine, Cardiff University, Cardiff, UK.|MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Hadyn Ellis Building, Maindy Road, Cathays, Cardiff, CF24 4HQ, UK.
authors.forename: Jilu Princy
authors.initials: JP
authors.lastname: Mole
authors.affiliation: Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Cardiff, UK.|Institute of Psychological Medicine and Clinical Neurosciences (IPMCN), School of Medicine, Cardiff University, Cardiff, UK.|MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Hadyn Ellis Building, Maindy Road, Cathays, Cardiff, CF24 4HQ, UK.
authors.forename: Leena
authors.initials: L
authors.lastname: Subramanian
authors.affiliation: Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Cardiff, UK.|Department of Psychiatry, University of Bern, Bern, Switzerland.
authors.forename: Tobias
authors.initials: T
authors.lastname: Bracht
authors.affiliation: Department of Clinical Neurology, Institute of Neurology, University College London, London, UK.
authors.forename: Huw
authors.initials: H
authors.lastname: Morris
authors.affiliation: Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Cardiff, UK.
authors.forename: Claudia
authors.initials: C
authors.lastname: Metzler-Baddeley
authors.affiliation: Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Cardiff, UK. lindend@cardiff.ac.uk.|Institute of Psychological Medicine and Clinical Neurosciences (IPMCN), School of Medicine, Cardiff University, Cardiff, UK. lindend@cardiff.ac.uk.|MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Hadyn Ellis Building, Maindy Road, Cathays, Cardiff, CF24 4HQ, UK. lindend@cardiff.ac.uk.
authors.forename: David E J
authors.initials: DE
authors.lastname: Linden
mesh_terms: D016880:Anisotropy; D001479:Basal Ganglia / Q000000981:diagnostic imaging*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000000981:diagnostic imaging; D009473:Neuronal Plasticity; D010300:Parkinson Disease / Q000175:diagnosis*
keywords: Deterministic tractography; Diffusion-weighted imaging; Fractional anisotropy; Neuroplasticity; Parkinson’s disease