Structural reserve-dependent cortical rerouting of motor control after stroke.
Valerie M Wiemer1,2, Theresa Paul1, Lukas Hensel1
1Faculty of Medicine, University of Cologne, and Department of Neurology, University Hospital Cologne, Cologne 50937, Germany.
Brain : a Journal of Neurology
|November 14, 2025
Summary
Undamaged brain pathways (structural reserve) guide motor recovery after stroke. The brain reroutes signals either within one hemisphere or across hemispheres, impacting motor function differently based on the available reserve.
Area of Science:
- Neuroscience
- Neurology
- Rehabilitation Medicine
Background:
- Structural cortico-cortical connectivity is crucial for motor recovery post-stroke.
- Undamaged white matter tracts act as a structural reserve for functional reorganization.
- Mechanisms linking structural reserve to functional network changes in motor control are unclear.
Purpose of the Study:
- To investigate how structural reserve influences motor network reorganization for upper limb motor control after stroke.
- To examine the relationship between structural connectivity features and functional network configurations.
Main Methods:
- Utilized diffusion spectrum imaging (DSI) for structural connectivity assessment.
- Employed functional MRI-based Dynamic Causal Modelling (DCM) for effective connectivity analysis.
- Correlated structural reserve characteristics with functional network reorganization patterns.
Main Results:
- Limited intrahemispheric structural reserve led to interhemispheric rerouting, especially with low corticospinal tract integrity.
- Limited interhemispheric structural reserve promoted intrahemispheric rerouting, particularly with high corticospinal tract integrity.
- Intrahemispheric rerouting correlated with better hand function (beneficial), while interhemispheric rerouting was linked to poorer motor function (maladaptive).
Conclusions:
- Available structural reserve critically shapes functional reorganization by directing intra- or interhemispheric rerouting.
- The pattern of rerouting has distinct implications for motor recovery outcomes.
- Considering individual structural reserve is vital for future stroke rehabilitation strategies.
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