Enhanced interhemispheric functional connectivity compensates for anatomical connection damages in subcortical stroke

Area of Science:

• Neuroscience
• Neuroimaging
• Stroke Rehabilitation

Background:

• Motor recovery after stroke is linked to corticospinal tract (CST) integrity and primary motor cortex (M1) functional connectivity.
• The specific role of M1-M1 resting-state functional connectivity (rsFC) in motor recovery is not well understood.

Purpose of the Study:

• To investigate the relationship between M1-M1 rsFC and the integrity of the M1-M1 anatomic connection and CST.
• To explore these correlations in chronic subcortical stroke patients with good motor outcomes.

Main Methods:

• Multimodal magnetic resonance imaging (MRI) including diffusion tensor imaging (DTI) and resting-state functional MRI (rs-fMRI).
• Reconstruction of M1-M1 anatomic connections and CSTs, assessment of white matter integrity using fractional anisotropy (FA).
• Calculation of M1-M1 rsFC and comparison between stroke patients and healthy controls.

Main Results:

• Stroke patients had reduced FA in the affected CST and M1-M1 anatomic connections compared to controls.
• Stroke patients exhibited significantly increased M1-M1 rsFC.
• FA of the affected CST correlated positively with M1-M1 anatomic connection integrity and negatively with M1-M1 rsFC.

Conclusions:

• M1-M1 anatomic connection impairment appears secondary to CST damage.
• Enhanced M1-M1 rsFC may indicate compensatory neural plasticity in response to CST impairment in stroke survivors.