Abnormal connectivity model of raphe nuclei with sensory-associated cortex in Parkinson's disease with chronic pain.

BACKGROUND AND OBJECTIVE: There are indicates that raphe nuclei may be involved in the occurrence of chronic pain in Parkinson's disease (PD). In the study, we investigated the functional connectivity pattern of raphe nuclei in Parkinson's disease with chronic pain (PDP) to uncover its possible pathophysiology. METHODS: Fifteen PDP, who suffered from pain, lasted longer than 3 months, sixteen Parkinson's disease patients with no pain (nPDP) and eighteen matched normal health controls (NCs) were recruited. All subjects completed the King's Parkinson's Pain Scale (KPPS) besides Parkinson-related scale and demographics. We performed a seed-based resting-state analysis of functional magnetic resonance imaging to explore whole-brain functional connectivity of the raphe nuclei. Multiple regression model was used to explore the related factors of pain including disease duration, disease severity, Hamilton Depression Rating Scale, age, sex, levodopa equivalent dose and the strength of network functional connectivity. RESULTS: Compared with the nPDP, the PDP group showed stronger functional connectivity between raphe nuclei and pain-related brain regions, including parietal lobe, insular lobe, cingulum cortex and prefrontal cortex, and the functional connectivity values of those areas were significantly positively correlated with KPPS independent of the clinical variables. Compared with NCs, the combined PD groups showed decreased functional connectivity including prefrontal cortex and cingulum cortex. CONCLUSIONS: Abnormal functional connectivity model of raphe nuclei may be partly involved in pathophysiological mechanism of pain in PD.

Disorganized resting-state functional connectivity between the dorsal attention network and intrinsic networks in Parkinson's disease with freezing of gait.

Freezing of gait (FOG) is a common and complex manifestation of Parkinson's disease (PD) and is associated with impairment of attention. The purpose of this study was to evaluate the functional network connectivity (FNc) changes between the dorsal attention network (DAN) and the other seven intrinsic networks relevant to attention, visual-spatial, executive and motor functions in PD with or without FOG. Forty-three idiopathic PD patients (21 with FOG [FOG+] versus 22 without FOG [FOG-]) and 18 healthy controls (HC) were recruited in this study. The data-driven independent component analysis (ICA) method was used to extract and analyze the above-mentioned resting-state networks (RSNs). Compared with FOG-, FOG+ displayed decreased positive connectivity between the DAN and medial visual network (mVN) and sensory-motor network (SMN) and increased negative connectivity between the DAN and default mode network (DMN). The within-network connectivity in the SMN and visual networks were decreased, whereas the connectivity within DMN was increased significantly in FOG+. Correlation analysis showed that the clock drawing test (CDT) scores were positively correlated with the functional connectivity of mVN (r = 0.573, p = 0.008) and lateral visual network (lVN) (r = 0.510, p = 0.022), the Timed Up and Go Test (TUG) duration were negatively correlated with the connectivity of SMN (r = -0.629, p = 0.003), and the Frontal Assessment Battery (FAB) scores were negatively correlated with the connectivity of DMN in FOG+. Functional connectivity was changed in multiple intra-networks in patients with FOG. Inordinate inter-network connectivity between the DAN and other intrinsic networks may partly contribute to the mechanism of freezing.

Different functional connectivity modes of the right fronto-insular cortex in akinetic-rigid and tremor-dominant Parkinson's disease.

BACKGROUND: Patients with akinetic-rigid Parkinson's disease (AR-PD) are more prone to cognitive decline and depressive symptoms than tremor-dominant PD (TD-PD) patients. The right fronto-insular cortex (rFIC), as a key node of salience network, plays a critical role in the switching between central executive network and default mode network. In this study, we explored the functional connectivity mode of rFIC with triple-brain networks, namely default mode network, salience network, and central executive network, in two motor subtypes of PD. METHODS: We recruited 44 PD patients (including the TD-PD group and AR-PD group) and 18 age-matched healthy controls (HCs). We performed functional connectivity (FC) analysis of resting-state functional MRI. RESULTS: Compared with TD-PD, decreased FC were found in the right insular cortex and bilateral anterior cingulate gyrus in AR-PD. Compared with HCs, decreased FC in the bilateral insula, the anterior cingulate gyrus, the precentral gyrus, and the right medial frontal gyrus were found; therein, the FC value of rFIC-precentral gyrus was positively correlated with the Unified Parkinson's Disease Rating Scale-II score in AR-PD (p = 0.0482, r = 0.4162). While TD-PD showed decreased FC in the left insula as well as bilateral anterior cingulate gyrus when compared with HCs, and the FC value of the rFIC-left insula was positively correlated with its Hamilton Depression Rating Scale score (p = 0.02, r = 0.50). CONCLUSION: The functional connectivity mode of rFIC in AR-PD differed from that in TD-PD. The decreased rFIC FC with the other nodes of salience network might be a potential indicator for AR-PD patients prone to develop cognitive decline and depressive symptoms.