Synchronization within, and interactions between, the default mode and dorsal attention networks in relapsing-remitting multiple sclerosis

Figures & data

Table 1 Demographic and clinical characteristics of the study population

	Remitting patients	Healthy controls	p-value
Gender (M/F)	12/21	12/21	1
Mean age (range), years	41.8 (20–58)	42.2 (23–58)	0.901
Mean disease duration (range), months	27.0 (1.5–150)	–	n/a
BPF	0.827 ± 0.003	0.862 ± 0.003	0.000
TWMLL, mL	18.69 ± 3.27	–	n/a
Mean EDSS (range)	1.97 (0–3.5)	–	n/a
MFIS	17.0 ± 10.9	–	n/a
Mean head motion*, mm	0.0413 ± 0.054	0.0388 ± 0.014	0.457

Notes: –, no data.

* Head motion according to the criteria of Van Dijk.

Abbreviations: BPF, brain parenchymal fraction; EDSS, Expanded Disability Status Scale; F, female; M, male; MFIS, Modified Fatigue Impact Scale; n/a, not applicable; TWMLL, total white matter lesion load.

Figure 1 DMN and DAN of remitting-phase RRMS patients (right column) and HCs (left column) (one-sample t-test, p < 0.05, Bonferroni corrected). ICx: independent component x obtained by group ICA.

Abbreviations: DAN, dorsal attention network; DMN, default mode network; HC, healthy control; HF, high frequency; ICA, independent component analysis; LF, low frequency; MS, multiple sclerosis; RRMS, relapsing-remitting multiple sclerosis.

Figure 2 Compared with the HCs, significantly altered FC was observed in the remitting-phase RRMS patients (two-tailed voxel-level, p < 0.01; cluster-level, p < 0.05; GRF corrected).

Abbreviations: AG, angular gyrus; DAN, dorsal attention network; DMN, default mode network; FC, functional connectivity; GRF, Gaussian random field; HC, healthy control; pHipp, parahippocampal gyrus; POCG, postcentral gyrus; RRMS, relapsing-remitting multiple sclerosis; SFG, superior frontal gyrus; STG, superior temporal gyrus.

Table 2 Group comparisons of the ICs (subnetworks) of the DAN and DMN between the remitting-phase RRMS patients and the HCs

Anatomical location	Cluster size	MNI coordinates of peak			t-value	Mean ± standard error	Effect size
		x (mm)	y (mm)	z (mm)
DAN IC09 (remitting-phase RRMS vs HC)
Left POCG	37	−27	−39	48	−3.735	0.61 ± 0.06 vs 1.01 ± 0.07	0.476
DMN IC12 (remitting-phase RRMS vs HC)
Right AG	38	48	−57	27	−3.534	1.01 ± 0.12 vs 1.75 ± 0.15	0.423
Right SFG	40	27	36	51	−3.378	0.61 ± 0.10 vs 1.22 ± 0.11	0.440
DMN IC23 (remitting-phase RRMS vs HC)
Right pHipp	28	33	−18	−30	3.521	0.61 ± 0.06 vs 0.25 ± 0.05	0.471
Right STG	30	51	−48	21	−3.842	0.52 ± 0.10 vs 1.24 ± 0.14	0.461

Abbreviations: AG, angular gyrus; DAN, dorsal attention network; DMN, default mode network; HC, healthy control; IC, independent component; MNI, Montreal Neurological Institute; POCG, postcentral gyrus; pHipp, parahippocampal gyrus; RRMS, relapsing-remitting multiple sclerosis; SFG, superior frontal gyrus; STG, superior temporal gyrus.

Figure 3 FNC analysis in the HCs and the remitting-phase RRMS patients.

Abbreviations: Corr, correlation; DAN, dorsal attention network; DMN, default mode network; FNC, functional network connectivity; HC, healthy control; IC, independent component; MS, multiple sclerosis; RRMS, relapsing-remitting multiple sclerosis; val, value.

Figure 4 Significant alterations in the GCT in the spectral domain between the HCs and the remitting-phase RRMS patients.

Note: B > A means component B is larger than component A, eg, in the bar of IC23-IC12, warm-toned (red) means IC12 is larger than IC23, and cold-toned (blue) means IC23 is larger than IC12 in frequency (Hz) of GCT analyses.
Abbreviations: Corr, correlation; DAN, dorsal attention network; DMN, default mode network; GCT, Granger causality test; HC, healthy control; IC, independent component; MS, multiple sclerosis; RRMS, relapsing-remitting multiple sclerosis; val, value.

Figure 5 Correlations between the clinical measures (MFIS) and the altered connectivity coefficients of the remitting-phase RRMS patients.

Abbreviations: ICA, independent component analysis; MFIS, Modified Fatigue Impact Scale; RRMS, relapsing-remitting multiple sclerosis; STG, superior temporal gyrus.