Dynamic Reconfiguration of Cognitive Networks and Recovery From Microlesion Effects in Parkinson's Disease: Insights From a Longitudinal fNIRS Study.

BACKGROUND

Bilateral subthalamic nucleus deep brain stimulation (STN-DBS) significantly improves motor symptoms in advanced Parkinson's disease (PD). However, the perioperative "microlesion effect" (MLE) is often associated with cognitive dysfunction, notably declines in verbal fluency (VFT). The dynamic neural mechanisms underlying cognitive network impairment during the MLE phase and functional reorganization following DBS stimulation remain poorly understood.

AIMS AND

METHODS

This study employed longitudinal task-based functional near-infrared spectroscopy (fNIRS) to prospectively track 20 PD patients undergoing bilateral STN-DBS. To effectively disentangle the effects of natural surgical recovery from those specific to electrical stimulation, data were collected at four critical time points: 1 day preoperatively (Pre, T0), 7 days postoperatively (MLE phase, Post, T1), 1 month postoperatively with stimulation off (endpoint of natural recovery, Off, T2), and 1 week after stimulation onset (T3). VFT behavioral performance and global cognitive function (MoCA) were assessed concurrently. Hemodynamic signals from fNIRS were analyzed to examine activation changes in the prefrontal-temporal cortices. Furthermore, graph theory analysis was applied to quantify the dynamic evolution of topological properties within the core cognitive and motor networks.

RESULTS

VFT scores dropped during MLE (8.70 ± 2.30 to 5.70 ± 1.78, p < 0.01), partially recovering post-stimulation (8.15 ± 2.48, p < 0.05). MoCA scores also declined in MLE (25.40 ± 1.27 to 21.95 ± 1.10, p < 0.001). Neuroimaging showed activated channels decreased from 8 preoperatively to 2 during MLE (FDR-corrected), followed by reactivation to 12 channels after stimulation, particularly in dorsolateral/ventrolateral prefrontal regions. Between-group comparisons revealed enhanced activation in right DLPFC (Ch6), right SMA (Ch19), and left VLPFC (Ch47) after stimulation versus MLE (all p < 0.05, FDR-corrected).

CONCLUSION

Our findings indicate that MLE-related cognitive decline may stem from acute local network disruption, while DBS can promote functional reorganization of cognitive networks. fNIRS proves to be a valuable tool for monitoring DBS-induced neuroplasticity in PD.