Dynamic thalamocortical functional connectivity disruptions in Parkinson’s disease with probable REM sleep behavior disorder

As the symptom of rapid eye movement sleep behavior disorder (RBD) is paroxysmal during sleeping, the disruptions of dynamic functional connectivity (FC) between thalamic subnuclei and the cortex may play a critical role in Parkinson's disease (PD). A total of 35 PD patients with probable RBD (PD-pRBD) and 40 PD patients without probable RBD (PD-npRBD) and 41 healthy controls were enrolled. All participants underwent functional magnetic resonance imaging scan and clinical assessment. Altered dynamic FC between bilateral 14 thalamic nuclei and cortex was calculated. Although the RBDSQ demonstrates high diagnostic accuracy, polysomnographic validation would strengthen diagnostic certainty and enable more precise phenotyping of RBD severity. However, the current limitation of RBD diagnosis-relying solely on RBDSQ scores without polysomnographic confirmation-does not inherently compromise the outcome. PD-pRBD showed greater FC fluctuations between: (1) bilateral mediodorsal lateral parvocellular (MDL) nuclei and cerebellar anterior lobe (CAL); (2) right pulvinar lateral nucleus and left calcarine cortex; and (3) right ventral posterolateral nucleus and right cerebellum. Conversely, dynamic FC between the left pulvinar medial nucleus (PuM) and left superior parietal lobule, and between the right PuM nucleus and right inferior parietal lobule, were elevated in PD-npRBD. There was a positive correlation between the dynamic FC of bilateral MDL nuclei and the CAL with clinical severity within the PD-pRBD. Alterations in thalamocortical dynamic FC may be a potential biomarker for monitoring the paroxysmal nature of RBD in PD.