Resting-state connectivity and task-based cortical response in post-stroke executive dysfunction: A fNIRS study.

OBJECTIVE

This study attempted to investigate the frontoparietal cortical reorganization associated with executive function (EF) in post-stroke executive dysfunction (PSED) patients, focusing on resting-state, Stroop and 1-back task-based functional connectivity (FC) using functional near-infrared spectroscopy (fNIRS).

METHODS

We recorded oxygenated hemoglobin concentration signals from bilateral inferior parietal lobule (R_IPL/L_IPL), pre-motor area (R_PMA/L_PMA), dorsolateral prefrontal cortex (R_DLPFC/L_DLPFC), Broca's area (R_Broca/L_Broca) and frontopolar cortex (FPC) of 20 PSED patients and 20 healthy controls (HCs). We compared group differences in cortical response, including functional connectivity (FC) during resting-state, task-based FC during Stroop and 1-back task as well as cortical activation during these tasks. Additionally, we analyzed the correlation between MoCA scores, task performance, and any specific cortical response that showed differences.

RESULTS

PSED patients exhibited hypoactivation in executive-related regions during both Stroop and 1-back tasks compared to HCs. During the Stroop task, cross-hemispheric hyperconnectivity from the left inferior parietal lobule (IPL) to the right Broca's area suggested compensatory adaptation. During the 1-back task, within-frontal and intra-hemispheric hypoconnectivity indicated maladaptive neural reorganization. Correlation analyses revealed that increased directed FC from the left IPL to right Broca was positively associated with Stroop reaction time, while decreased directed FC from the right IPL to the frontopolar cortex (FPC) was negatively associated with 1-back task performance in PSED patients.

CONCLUSIONS

Our study highlights the importance of including the parietal cortex in fNIRS studies of PSED to obtain a comprehensive understanding of EF deficits. From the investigation of task-based cortical response, PSED patients exhibited different patterns of FC despite reduced task-based cortical activation: compensatory cross-hemispheric hyperconnectivity during the Stroop task, while maladaptive within-frontal and between IPL and frontopolar hypoconnectivity during the 1-back task. Incorporating the insights gained from our study, future research can explore multi-targeted neuromodulation strategies that address frontal and parietal cortices may be more effective in improving cognitive outcomes in stroke survivors.