title: Compensatory motor network connectivity is associated with motor sequence learning after subcortical stroke.
abstract: Following stroke, functional networks reorganize and the brain demonstrates widespread alterations in cortical activity. Implicit motor learning is preserved after stroke. However the manner in which brain reorganization occurs, and how it supports behavior within the damaged brain remains unclear. In this functional magnetic resonance imaging (fMRI) study, we evaluated whole brain patterns of functional connectivity during the performance of an implicit tracking task at baseline and retention, following 5 days of practice. Following motor practice, a significant difference in connectivity within a motor network, consisting of bihemispheric activation of the sensory and motor cortices, parietal lobules, cerebellar and occipital lobules, was observed at retention. Healthy subjects demonstrated greater activity within this motor network during sequence learning compared to random practice. The stroke group did not show the same level of functional network integration, presumably due to the heterogeneity of functional reorganization following stroke. In a secondary analysis, a binary mask of the functional network activated from the aforementioned whole brain analyses was created to assess within-network connectivity, decreasing the spatial distribution and large variability of activation that exists within the lesioned brain. The stroke group demonstrated reduced clusters of connectivity within the masked brain regions as compared to the whole brain approach. Connectivity within this smaller motor network correlated with repeated sequence performance on the retention test. Increased functional integration within the motor network may be an important neurophysiological predictor of motor learning-related change in individuals with stroke.
authors.affiliation: University of British Columbia, Faculty of Medicine, Department of Physical Therapy, 212-2177 Wesbrook Mall, Vancouver, BC V6T 1Z3, Canada.
authors.forename: Katie P
authors.initials: KP
authors.lastname: Wadden
authors.affiliation: Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada; BC Mental Health and Addictions Research Institute, Vancouver, BC, Canada.
authors.forename: Todd S
authors.initials: TS
authors.lastname: Woodward
authors.affiliation: Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada; BC Mental Health and Addictions Research Institute, Vancouver, BC, Canada.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Metzak
authors.affiliation: Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada; BC Mental Health and Addictions Research Institute, Vancouver, BC, Canada.
authors.forename: Katie M
authors.initials: KM
authors.lastname: Lavigne
authors.affiliation: University of British Columbia, Faculty of Medicine, Department of Physical Therapy, 212-2177 Wesbrook Mall, Vancouver, BC V6T 1Z3, Canada.
authors.forename: Bimal
authors.initials: B
authors.lastname: Lakhani
authors.affiliation: University of British Columbia, Faculty of Medicine, Department of Physical Therapy, 212-2177 Wesbrook Mall, Vancouver, BC V6T 1Z3, Canada.
authors.forename: Angela M
authors.initials: AM
authors.lastname: Auriat
authors.affiliation: University of British Columbia, Faculty of Medicine, Department of Physical Therapy, 212-2177 Wesbrook Mall, Vancouver, BC V6T 1Z3, Canada; Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada. Electronic address: lara.boyd@ubc.ca.
authors.forename: Lara A
authors.initials: LA
authors.lastname: Boyd
mesh_terms: D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007858:Learning / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009048:Motor Skills / Q000502:physiology*; D009434:Neural Pathways / Q000503:physiopathology; D025341:Principal Component Analysis; D020521:Stroke / Q000503:physiopathology* / Q000523:psychology
keywords: Constrained principal component analysis; Functional connectivity; Functional magnetic resonance imaging; Motor sequence learning; Stroke