Effects of tactile feedback in post-stroke hand rehabilitation on functional connectivity and cortical activation: an fNIRS study

Stroke-induced hand motor impairments have a significant impact on the daily lives of patients. Motor rehabilitation with tactile feedback (TF) shows promise as an effective rehabilitation intervention; however, its neural mechanisms are still not fully understood. The main objective of this study was to examine the effect of tactile feedback on brain functional responses during a single hand movement session in post-stroke patients, using functional near-infrared spectroscopy (fNIRS). The changes in oxy- and deoxy-hemoglobin concentrations were recorded from the bilateral prefrontal, motor, and occipital areas in 13 post-stroke patients in the subacute recovery phase and 15 healthy controls during a hand-grasping task with TF and no-TF. The cortical activation responses, functional connectivity, and brain functional network properties were calculated to explore the specific cortical response in post-stroke patients and healthy controls during the two grasping tasks. The results showed that post-stroke patients exhibited increased hemodynamic responses in the motor cortex during grasping tasks with TF. However, brain activation in the prefrontal cortex, left sensorimotor cortex, and right premotor area was significantly lower in post-stroke patients compared to healthy controls (p < 0.05). Additionally, post-stroke patients exhibited poorer overall brain network function, with significant reductions in both clustering coefficient (p = 0.0016), reflecting local information transfer efficiency, and transitivity (p = 0.0053), representing global network integration. A significant positive correlation was observed between the clustering coefficient and grip strength metrics (r = 0.592, p = 0.033), as well as between transitivity and grip strength (r = 0.590, p = 0.034) in post-stroke patients, indicating that greater impairments were associated with reduced overall brain functional network transmission efficiency. These findings indicated that TF can modulate brain activity in areas associated with motor learning and sensorimotor integration, providing evidence for its potential as a valuable tool in stroke rehabilitation.