Complex Brain Network Analysis and Its Applications to Brain Disorders: A Survey

Table 7

Overview of functional brain network studies in PD.

Study	Modality	Subjects	Node definition	Edge definition	Network type	Main findings
Skidmore et al., 2011 [122]	fMRI	14 PD; 15 HC	116 regions in AAL atlas	Wavelet correlation	Weighted	(1) Decreased global efficiency in PD.; (2) Decreased nodal efficiency the left supplementary motor cortex, contiguous precentral regions, the calcarine cortices, secondary visual regions, and the certain regions within the cerebellum in PD.
Göttlich et al., 2013 [123]	fMRI	37 PD; 20 HC	343 regions	Zero-lag Pearson correlation	Binary	(1) Lower global efficiency in PD in PD.; (2) Increased connectivity within the sensorimotor network and decreased interaction of the visual network with other brain modules in PD.; (3) Lower connectivity between the cuneus and the ventral caudate, medial orbitofrontal cortex, and the temporal lobe.; (4) Decreased degree in the occipital lobe and increased degree in the superior parietal cortex, posterior cingulate gyrus, supramarginal gyrus, and supplementary motor area.
Luo et al., 2015 [124]	fMRI	47 PD; 47 HC	200 regions in [67]	Pearson correlation	Binary	(1) Lower clustering coefficient and local efficiency in PD.; (2) Reduced node centralities and connectivity strength in temporal-occipital and sensorimotor regions in PD.
Koshimori et al., 2016 [125]	fMRI	42 PD; 23 HC	120 regions in [61]	Pearson correlation	Binary	(1) Higher nodal degree in the right and left dorsolateral prefrontal cortex in PD.; (2) Reduced local efficiency the right mid-insula in PD.; (3) Reduced nodal betweenness centrality in the right presupplementary motor area in PD.
Olde Dubbelink et al., 2014 [126]	MEG	70 PD; 21 HC	78 regions in AAL atlas	Phase lag index	Weighted	(1) Lower local clustering coefficient with preserved path length in the delta frequency band in PD.; (2) Decreased local clustering coefficient in multiple frequency bands with decreased path length in the alpha2 frequency band in PD.
Utianski et al., 2016 [127]	EEG	18; PD-D; 57; PD-HC; 57 HC	8 epochs	Phase lag index	Weighted	(1) Higher connectivity strength in the theta band in PD-HC compared with HC.; (2) higher gamma, lambda, and modularity in PD-HC compared with HC.; (3) lower functional connectivity in the alpha1 band in PD-D compared with PD-HC.; (4) Lower gamma and lambda in the alpha1 band and higher modularity in both alpha bands in PD-D compared with PD-HC.