FREQUENCY-SPECIFIC FRONTO-PARIETAL NETWORK REORGANISATION DURING PRECISION AND POWER GRASPING AFTER STROKE

Dexterous grasping relies on the dynamic integration of fronto-parietal circuits: the dorsal stream, connecting the primary motor cortex (M1) to the anterior intraparietal sulcus (aIPS) for hand shaping, and the ventral stream, connecting M1 to the ventral premotor cortex (PMv) for stability. While stroke alters connectivity, it remains unclear if this reorganization is task-specific or a general upregulation, and how it relates to oscillatory frequencies and white matter integrity.
We recorded high-resolution 64-channel EEG in 17 chronic stroke patients and 18 controls during a reach-to-grasp task alternating between precision and power grips. Task-related source-level functional connectivity (imaginary coherence) between ipsilesional M1, aIPS, and PMv was quantified in beta (14-25 Hz) and low-frequency (LFO; 2-4 Hz) bands and associated with structural integrity within the network and motor impairment. Patients showed prolonged grasp execution rather than reach initiation compared to controls. Upregulation of functional connectivity in the beta band was grasp-and region-specific: M1-aIPS connectivity increased during precision grip (p < 0.01), whereas M1-PMv connectivity increased during power grip (p < 0.05). Conversely, LFO connectivity was generally reduced in patients. During precision grip, stronger M1-PMv low-frequency oscillatory connectivity was associated with reduced tract integrity (p = 0.007), while lower connectivity was linked to greater motor impairment (p < 0.05). We conclude a frequency- and circuit-specific account of post-stroke network reorganisation in skilled grasping. Beta reflects flexible, task-dependent upregulation independent of structural damage, whereas LFO connectivity is reduced at the group level and exhibits pathway-specific clinical associations and is shaped by underlying tract integrity.