title: Functional connectivity of primary motor cortex is dependent on genetic burden in prodromal Huntington disease.
abstract: Subtle changes in motor function have been observed in individuals with prodromal Huntington disease (prHD), but the underlying neural mechanisms are not well understood nor is the cumulative effect of the disease (disease burden) on functional connectivity. The present study examined the resting-state functional magnetic resonance imaging (rs-fMRI) connectivity of the primary motor cortex (M1) in 16 gene-negative (NEG) controls and 48 gene-positive prHD participants with various levels of disease burden. The results showed that the strength of the left M1 connectivity with the ipsilateral M1 and somatosensory areas decreased as disease burden increased and correlated with motor symptoms. Weakened M1 connectivity within the motor areas was also associated with abnormalities in long-range connections that evolved with disease burden. In this study, M1 connectivity was decreased with visual centers (bilateral cuneus), but increased with a hub of the default mode network (DMN; posterior cingulate cortex). Changes in connectivity measures were associated with worse performance on measures of cognitive-motor functioning. Short- and long-range functional connectivity disturbances were also associated with volume loss in the basal ganglia, suggesting that weakened M1 connectivity is partly a manifestation of striatal atrophy. Altogether, the results indicate that the prodromal phase of HD is associated with abnormal interhemispheric interactions among motor areas and disturbances in the connectivity of M1 with visual centers and the DMN. These changes may, respectively, contribute to increased motor symptoms, visuomotor integration problems, and deficits in the executive control of movement as individuals approach a manifest diagnosis.
authors: 1 Imaging Institute, Cleveland Clinic , Cleveland, Ohio.
authors: Katherine A
authors: KA
authors: Koenig
authors: Mark J
authors: MJ
authors: Lowe
authors: Deborah L
authors: DL
authors: Harrington
authors: Jian
authors: J
authors: Lin
authors: Sally
authors: S
authors: Durgerian
authors: Lyla
authors: L
authors: Mourany
authors: Jane S
authors: JS
authors: Paulsen
authors: Stephen M
authors: SM
authors: Rao
mesh_terms: D000328:Adult; D001921:Brain / Q000503:physiopathology; D001931:Brain Mapping; D005260:Female; D006801:Humans; D006816:Huntington Disease / Q000235:genetics* / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009415:Nerve Net / Q000503:physiopathology*; D062706:Prodromal Symptoms; D013003:Somatosensory Cortex / Q000503:physiopathology
keywords: Huntington disease; functional connectivity; motor cortex; motor system; seed voxel analysis