Bilateral versus ipsilesional cortico-subcortical activity patterns in stroke show hemispheric dependence

Area of Science:

• Clinical Neuroscience
• Neurorehabilitation
• Motor Control

Background:

• Interhemispheric interactions in stroke patients are crucial for understanding motor control and neurorehabilitation.
• Bilateral overactivation is linked to poor recovery, while ipsilesional patterns suggest better outcomes.

Purpose of the Study:

• To investigate hemispheric interaction pathophysiology during limb movement.
• To mimic constraint-induced movement therapy effects using neuroimaging.

Main Methods:

• Used functional magnetic resonance imaging (fMRI) with a block design.
• Recruited plegic/paretic upper limb for unilateral arm elevation with and without contralateral limb restriction.
• Included 20 stroke participants with balanced left/right lesion sites.

Main Results:

• Right-hemispheric stroke showed bilateral sensorimotor cortex activation; left-hemispheric stroke showed unilateral dominance.
• Contralateral restriction shifted activation to deactivation in right-hemispheric stroke motor areas.
• Left-hemispheric stroke exhibited reduced activation, with further cortical silencing upon restriction.

Conclusions:

• Observed novel hemispheric-dependent activation/deactivation shifts.
• These findings suggest short-term neuroplasticity.
• Results may inform hemisphere-tailored neurorehabilitation approaches.