Differential cortical responses of robot-assisted active and mirror therapy task conditions in stroke patients and...

Robot-assisted task conditions incorporating Active Movement Mode (AMM) and Mirror Therapy Mode (MTM) is widely used for upper-limb stroke rehabilitation. However, their differential task-related cortical responses remain insufficiently characterized.

This study aimed to use functional near-infrared spectroscopy (fNIRS) to characterize and compare the task-dependent cortical activation and rest state functional connectivity profiles elicited by AMM and MTM in stroke patients and healthy controls.

Twenty-three chronic stroke patients and twenty-three matched healthy controls performed robot-assisted upper limb tasks in both AMM and MTM. Cortical activation (Beta value) in the prefrontal (PFC), primary motor (M1), supplementary motor (SMA), premotor (PMC), and primary somatosensory (PSC) cortices was measured using a 48-channel fNIRS system. A Two-way repeated measures ANOVA to compare cortical activation; Hemispheric activation distribution was assessed by calculating the lateralization index (LI). To evaluate brain-behavior relationships, we used Pearson or Spearman correlation analyses to examine the association between ROI activation levels and FMA-UE scores. Furthermore, resting-state functional connectivity (RSFC) was compared between eyes-open and eyes-closed conditions. All multiple comparisons were corrected using the Benjamini-Hochberg FDR method.

Both groups showed extensive cortical activation across both modes ( $p<0.01$ ). Analysis of variance indicated significant main effects of task in the ipsilesional PFC and PSC, along with the contralesional PFC and PMC ( $p<0.05$ ), where activation in the AMM mode was consistently higher than in the MTM mode. Resting-state analysis revealed that stroke patients had significantly weaker inter-hemispheric and intra-hemispheric RSFC in the eye-open (EO) condition than healthy controls ( $p<0.05$ ). No significant correlations between brain activity and behavior or lateralization effects were found.

Active Movement Mode and Mirror Therapy Mode exhibited distinct cortical activation and functional connectivity profiles during robot-assisted upper-limb tasks. Compared with MTM, AMM was associated with stronger recruitment of several motor-related regions, while differences in connectivity further supported distinct modes of neural engagement.

Unique identifier: ChiCTR2500096992, URL: https://www.chictr.org.cn.