Abnormal intrinsic brain functional network dynamics in Parkinson’s disease

Abstract

for a scientific commentary on this article. Parkinson's disease is a neurodegenerative disorder characterized by nigrostriatal dopamine depletion. Previous studies measuring spontaneous brain activity using resting state functional magnetic resonance imaging have reported abnormal changes in broadly distributed whole-brain networks. Although resting state functional connectivity, estimating temporal correlations between brain regions, is measured with the assumption that intrinsic fluctuations throughout the scan are stable, dynamic changes of functional connectivity have recently been suggested to reflect aspects of functional capacity of neural systems, and thus may serve as biomarkers of disease. The present work is the first study to investigate the dynamic functional connectivity in patients with Parkinson's disease, with a focus on the temporal properties of functional connectivity states as well as the variability of network topological organization using resting state functional magnetic resonance imaging. Thirty-one Parkinson's disease patients and 23 healthy controls were studied using group spatial independent component analysis, a sliding windows approach, and graph-theory methods. The dynamic functional connectivity analyses suggested two discrete connectivity configurations: a more frequent, sparsely connected within-network state (State I) and a less frequent, more strongly interconnected between-network state (State II). In patients with Parkinson's disease, the occurrence of the sparsely connected State I dropped by 12.62%, while the expression of the more strongly interconnected State II increased by the same amount. This was consistent with the altered temporal properties of the dynamic functional connectivity characterized by a shortening of the dwell time of State I and by a proportional increase of the dwell time pattern in State II. These changes are suggestive of a reduction in functional segregation among networks and are correlated with the clinical severity of Parkinson's disease symptoms. Additionally, there was a higher variability in the network global efficiency, suggesting an abnormal global integration of the brain networks. The altered functional segregation and abnormal global integration in brain networks confirmed the vulnerability of functional connectivity networks in Parkinson's disease.

Regional and network properties of white matter function in Parkinson's disease

“…Conversely, WM functional networks become more optimal in PD patients. This was different from previous findings concerning WM structure (Galantucci et al, 2017) and GM function (Gottlich et al, 2013;Kim et al, 2017) in PD patients, and suggests a functionalstructural decoupling at the network level.…”

Dynamic functional connectivity changes in dementia with Lewy bodies and Alzheimer’s disease

“…Similar to our results, Peraza et al (2015) reported no difference between AD and controls with respect to global efficiency which indicates that static and dynamic changes in efficiency might be a specific feature of DLB that might not be associated with dementia per se. In contrast to our results, Kim et al (2017) found increased variability of global efficiency in PD. However, this finding was not replicated in another study in PD patients with mild cognitive impairment and thus further research will be needed to identify the specific changes related to these different Lewy body diseases.…”

Static and dynamic connectomics differentiate between depressed patients with and without suicidal ideation

“…Just one previous static connectomic study has found that MDD with SI reduced functional connectivity in the orbitofrontal‐thalamic network (Kim et al, b). In addition, the nodal properties (i.e., nodal strengths, nodal clustering coefficients, and nodal efficiency) of the left orbital part of the superior frontal and the bilateral thalamus gyrus were significantly correlated with SSI scores (Kim et al, b). Consistent with previous findings on static connectomic, we found that the putamen, temporal, and frontal cortices showed group differences.…”

“…Recently, resting‐state (absence of the stimulus) functional magnetic resonance imaging (fMRI) studies have reported that depressed patients with SI exhibited disrupted functional connectivity between the rostral anterior cingulate cortex and orbitomedial prefrontal cortex, that is, brain regions associated with decision‐making and emotional processing in SI (Du et al, ). In addition to the aforementioned seed‐based analysis of functional connectivity, recent functional connectomic study suggested that MDD with SI is characterized by decreased functional connectivity in the orbitofrontal‐thalamic circuits (Kim et al, b). Moreover, an anatomical connectomic study suggested that MDD with SI was associated with a reduction of the anatomical connectivity in frontal–subcortical circuits (Myung et al, ).…”