Fronto-parietal involvement in chronic stroke motor performance when corticospinal tract integrity is compromised

Area of Science:

• Neuroscience
• Neurology
• Rehabilitation Medicine

Background:

• Corticospinal tract (CST) integrity is crucial for upper-limb function and recovery post-stroke.
• Mechanisms facilitating motor recovery in stroke survivors with significant CST damage remain poorly understood.

Purpose of the Study:

• Investigate resting-state functional connectivity in chronic stroke survivors with varying CST damage levels.
• Explore neural correlates of upper-limb motor performance in individuals with compromised ipsilesional CST integrity.

Main Methods:

• 30 chronic stroke survivors underwent MRI (structural and resting-state functional) and transcranial magnetic stimulation (TMS).
• CST integrity was assessed using TMS and diffusion MRI (fractional anisotropy).
• Participants were grouped based on the extent of CST damage.

Main Results:

• Stroke survivors with extensive CST damage exhibited weaker ipsilesional sensorimotor network connectivity and stronger ipsilesional fronto-parietal network connectivity.
• Improved upper-limb motor performance in the extensive CST damage group correlated with greater fronto-parietal network connectivity and higher fractional anisotropy in the rostral superior longitudinal fasciculus.

Conclusions:

• Extensive CST damage in stroke survivors is associated with increased resting-state functional connectivity in the ipsilesional fronto-parietal network.
• This enhanced fronto-parietal connectivity appears to be a behaviorally relevant neural mechanism supporting upper-limb motor recovery.