Recovered grasping performance after stroke depends on interhemispheric frontoparietal connectivity.

Area of Science:

• Neuroscience
• Neurology
• Rehabilitation Science

Background:

• Post-stroke parietal cortex activity and interhemispheric connectivity changes are common but their role in motor recovery is unclear.
• Understanding these neural changes is crucial for developing effective rehabilitation strategies for hand motor function.

Purpose of the Study:

• To investigate the contribution of ipsilesional and contralesional anterior intraparietal cortex (aIPS) to hand motor function after stroke.
• To explore the relationship between interhemispheric connectivity and motor recovery outcomes in stroke patients.

Main Methods:

• Multimodal assessment in 18 recovered chronic stroke patients and 18 controls.
• Included resting-state fMRI, task-based fMRI, repetitive transcranial magnetic stimulation (rTMS), and 3D movement kinematics.
• Stimulation targeted aIPS and M1, with sham and other control sites.

Main Results:

• Increased resting-state connectivity between ipsilesional aIPS and contralesional aIPS, and ipsilesional aIPS and dorsal premotor cortex, was linked to better motor outcomes.
• Interhemispheric connectivity between M1 and aIPS regions correlated with improved motor performance.
• rTMS interference revealed distinct roles: contralesional aIPS affected grasping accuracy, while contralesional M1 impacted grasping speed.

Conclusions:

• Contralesional M1 and aIPS play differential roles in specific aspects of recovered hand motor function.
• The reorganization of interhemispheric connectivity significantly influences the functional contributions of these brain regions.
• Findings highlight the importance of targeted interventions based on individual connectivity patterns for stroke rehabilitation.