Table 4.

Network analysis of structural connectivity in schizophrenia.

Study	Network type	Subjects	Node definition	Edge definition	Analysis	Global results*	Local Results*	Hubs*
Bassett et al., 2008	Structural correlation (1.5 T)	203 SCZ	108 regions Pick atlas	Binary, correlation between region volumes	Graph theory	=SW, K distribution	↓hierarchy, ↑mean C distance in multimodal network	↓PFC hubs
		259 HC					≠ CC, K and B in PreM, PFC, OFC, ITG, MTG, CG, Ins	↑ITG, Ins, CG hubs
Zhang et al., 2012b	Structural correlation (1.5 T)	101 SCZ	78 regions AAL atlas	Binary, correlation between regional cortical thickness	Graph theory	↑PL, CC	↓B mainly in the association cortices	↑# of hubs
		101 HC					↑B in the primary and paralimbic cortices	↓association cortex hubs
								↑primary, paralimbic hubs
Collin et al., 2013	Structural correlation (1.5T)	146 SCZ	(1) 12 lobes	Binary, correlation between region volumes	C compare (lobes)	n/a	↓C frontal <-> subcortical	n/a
		122 HC	(2) 82 regions Freesurfer		NBS (regions)		↑C temporal <-> subcortical; L frontal <-> R frontal; frontal <-> limbic impaired networks:1)
							PFC, temporal, occipital, parietal, limbic 2) SMG, Post-CG, CG, subcortical (NBS)
Shi et al., 2012	Structural correlation (3T)	26 high risk neonates$	90 regions adapted AAL atlas	Binary, correlation between region volumes	Graph theory	↓Eglob, inter-module C	n/a	=frontal, temporal hubs
		26 HC neonates				↑Eloc, PL, CC, C distance		↑occipital hubs
								↓parietal, subcortical hubs
Shi et al., 2012	DTI white matter (3T, 6 dir)	26 high risk neonates	90 regions adapted AAL atlas	Binary, nodes linked if sufficient # of streamlines	Graph theory	=Eglob, Eloc, C distance	↓number of fibers in 4 right subcortical <-> cortical and 2 occipital <-> limbic Cs	=frontal, temporal, insula, limbic hubs
		26 HC neonates			C compare			↑occipital hubs
								↓parietal, subcortical hubs
van den Heuvel et al., 2010	DTI white matter (1.5T, 32dir)	40 SCZ	108 regions AAL atlas	Weighted by average MTR -nodes linked if sufficient # of streamlines	Graph theory	=SW, C strength, PL, CC	↑PL of frontal and temporal regions	↓B in frontal hubs
		40 HC					↓CC in HPC and paracentral lobule
Skudlarski et al., 2010	DTI White matter (3T, 12dir)	27 SCZ	6000 K means clustering	Weighted by # of streamlines	C compare	Decoupling between anatomical and functional C	↓C in in default mode and task positive networks	n/a
		27 HC
Zalesky et al., 2011	DTI white matter (1.5T, 64dir)	74 SCZ	82 regions AAL atlas	Binary, nodes linked if sufficient # of streamlines	Graph theory	=SW	↓C in AG <-> R MTG; R SFG <-> L SFG; L IFG <-> L Ins	n/a
		32 HC			C compare	↓K, Eglob	↓C in network of medial frontal regions connected to parietal and occipital lobes (NBS)
					NBS
Wang et al., 2012	DTI white matter (1.5T, 13dir)	79 SCZ	90 regions AAL atlas	Weighted by # of streamlines	Graph theory	↓Eglob	↓regional Eglob in frontal associative cortices, paralimbic/limbic and subcortical regions	=association cortex, paralimbic/ limbic hubs
		96 HC				=Eloc, SW
van den Heuvel et al., 2013	DTI white matter (3T, 32dir)	48 SCZ	82 regions	Weighted by # of streamlines	Graph theory	↓RC organization, C strength, Eglob, CC	↓RC organization most pronounced in cortical networks	=RC members: PCUN, SFG, SPG, Ins
		45 HC	Freesurfer			↑M	↓density of RC Cs
						=SW
Collin et al., 2014	DTI white matter (1.5T, 32dir)	40 SCZ	68 cortical regions	Weighted by # of streamlines	Graph theory	↓C strength, Eglob (HC>SCZ)	↓C strength: SFG, ITG ↓Eglob: ACG, SFG, and PreCG	≠C and CC over-represented in RC members
		54 SCZ siblings	Freesurfer		NBS	↓CC (HC>siblings>SCZ)	↓CC: SFG, ACG, OFG, PreCG and Ins	↓C over- represented in RC members (NBS)
		51 HC					↓RC and local C strength (HC>siblings>SCZ)
Ottet et al., 2013	DTI white matter (3T, 30dir)	46 22q11.2DS	82 regions	Binary, nodes linked if sufficient # of streamlines	graph theory	↑PL	↓centrality in 16 out of 65 nonhubs (25%)	↓centrality in 10 out of 17 hubs (58%): HPC, SPG and PreCG, MFG, SFG, PCUN, THAL
		48 HC	Freesurfer			↓Eglob, K
						=CC
Zhang et al., 2014	DTI white matter (1.5T, 15dir)	30 FE-SCZ	90 regions AAL atlas	Weighted by # of streamlines	graph theory	=SW	↓Eglob and K in sensorimotor, basal ganglia, and limbic-visual systems	=hubs: PCUN, FG, MTG, ITG, SPG, post-CG
		34 HC			NBS	↓C strength, Eglob, K	↓C in subnetwork of frontal, parietal, occipital and subcortical regions (NBS)	↓hubs: MFG, post-CG and PreCG
						↑PL

^*Results reported in patient groups relative to controls unless otherwise indicated;

^$High risk neonates have mothers with schizophrenia.

SCZ, schizophrenia; SA, schizoaffective disorder; SF, schizophreniform disorder; FE-SCZ, first episode, medication naïve schizophrenia; HC, healthy control; 22q11.2DS - 22q11.2 deletion syndrome; NBS, network based statistics; MTR, magnetization transfer ratio; AAL, Automated Anatomical Labeling atlas (Tzourio-Mazoyer et al., 2002); LPBA40, LONI Probabilistic Brain Atlas (Shattuck et al., 2008).

Graph theory metrics: SW, small world organization; CC, clustering coefficient; PL, mean path length; K, degree; B, betweenness centrality; Eglob, global efficiency; Eloc, local efficiency; C, connectivity; M, modularity; RC, rich club.

Symbols: <->, between; #, number; ↑, increased; ↓, decreased; =, equivalent; ≠, different.

Brain regions: AG, angular gyrus; CG, cingulate gyrus; HPC, hippocampus; IFG, inferior frontal gyrus; Ins, Insular cortex; ITG, inferior temporal gyrus; MFG, middle frontal gyrus; MTG, middle temporal gyrus; OFC, orbital frontal cortex; PCUN, precuneus; PFC, prefrontal cortex; PreCG, precentral gyrus; PreM, premotor cortex; SFG, superior frontal gyrus; SPG, superior parietal gyrus; THAL, thalamus.