Thalamocortical functional connectivity in patients with insomnia using resting-state fMRI

Nambeom Kim; Eunsoo Won; Seo-Eun Cho; Chang-Ki Kang; Seung-Gul Kang

doi:10.1503/jpn.210066

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Figure 1
Cortical areas of increased thalamocortical functional connectivity in participants with insomnia compared with healthy controls. (A and B) The seed is the right thalamus. The insomnia group showed increased functional connectivity in the right superior medial frontal area, bilateral middle temporal areas, right parahippocampal gyrus and left rectus (areas in red) with the right thalamus compared with the healthy control group. (C and D) The seed is the left thalamus. The insomnia group showed increased functional connectivity in the left superior parietal area, both mid-temporal poles and left rectus (areas in red) with the left thalamus compared with the healthy control group. The green and red contours represent the left and right seeds of the thalamus, respectively. The statistical threshold was a voxel-wise uncorrected p < 0.001, with a cluster-wise false discovery rate corrected p < 0.05.
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Figure 2
Mean and standard errors for Fisher z-scores of resting-state functional connectivity between the thalamus and cortical regions. Resting-state functional connectivity was defined as Fisher z-scores in the INS and CON groups. (A) Correlations between the right thalamus and cortical regions and (B) between the left thalamus and cortical regions. Bars and whiskers represent means and standard errors. CON = healthy control; Frontal_Sup_Medial_R = right medial superior frontal area; INS = insomnia; ParaHippocampal_R = right parahippocampal area; Parietal_Sup_L = left superior parietal area; Rectus_L = left rectus; Temporal_Mid_R = right middle temporal area; Temporal_Pole_Mid_L = left middle temporal pole; Temporal_Pole_Mid_R = right middle temporal pole.

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Table 1

Demographic and clinical characteristics of the participants

Characteristic	Insomnia disorder n = 50	Healthy control n = 42	Statistics
Age, yr	43.3 ± 13.9	36.2 ± 11.2	t = 2.71, p = 0.008
Sex, female	33 (66.0)	26 (61.9)	χ² = 0.17, p = 0.7
Duration of insomnia disorder, yr	6.9 ± 7.8	—
Duration of education, yr	13.6 ± 3.8	15.4 ± 2.0	t = −2.88, p = 0.005
PSQI^*
Total score	12.9 ± 3.6	2.4 ± 1.3	t = 19.25, p < 0.001
TST, min	281.8 ± 89.0	445.5 ± 53.8	t = −10.86, p < 0.001
SE, %	64.9 ± 20.0	96.2 ± 4.2	t = −10.79, p < 0.001
ISI score^*	18.5 ± 4.8	1.3 ± 1.7	t = 23.73, p < 0.001
Polysomnographic data
TST, min	346.9 ± 73.3	394.3 ± 65.4	t = −3.24, p = 0.002
SE, %	77.7 ± 12.3	91.1 ± 7.1	t = −6.51, p < 0.001
WASO, min	73.2 ± 56.8	31.9 ± 29.2	t = 4.48, p < 0.001
AHI, no./h	3.4 ± 3.4	3.0 ± 4.4	t = 0.54, p = 0.6

AHI = apnea–hypopnea index; ISI = Insomnia Severity Index; PSQI = Pittsburgh Sleep Quality Index; SE = sleep efficiency; SOL = sleep onset latency; TST = total sleep time; WASO = wake-after-sleep onset.
Values are reported as mean ± standard deviation or n (%).
↵* These scales were completed on the date of the brain MRI scanning.

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Table 2

Coordinates of increased thalamocortical functional connectivity in participants with insomnia compared with healthy controls

Seed	Connected cortical region	MNI coordinates (x, y, z)			Cluster size	z-score
Right thalamus	Frontal_Sup_Medial_R	8	58	12	155	3.98
	Temporal_Pole_Mid_L	−54	12	−34	145	3.91
	ParaHippocampal_R	30	−32	−16	156	3.91
	Temporal_Mid_R	66	−4	−20	287	3.83
	Rectus_L	−2	48	−16	154	3.77
Left thalamus	Parietal_Sup_L	−18	−60	52	344	4.38
	Temporal_Pole_Mid_R	48	16	−32	337	4.27
	Rectus_L	−4	48	−16	159	3.97
	Temporal_Pole_Mid_L	−44	12	−34	189	3.93

Frontal_Sup_Medial_R = right medial superior frontal area; MNI = Montreal Neurological Institute; ParaHippocampal_R = right parahippocampal area; Parietal_Sup_L = left superior parietal area; Rectus_L = left rectus; Temporal_Mid_R = right middle temporal area; Temporal_Pole_Mid_L = left middle temporal pole; Temporal_Pole_Mid_R = right middle temporal pole.
We performed this analysis after controlling for age, sex and education level.

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Table 3

Partial correlation coefficients between sleep efficiency and functional connectivity in the insomnia group

Clinical index	Seed	Connected cortical region	Pearson coefficient	p value
Sleep efficiency from PSG	Right thalamus	Frontal_Sup_Medial_R	−0.28	0.049
		Temporal_Pole_Mid_L	−0.284	0.045
		ParaHippocampal_R	−0.295	0.04
		Temporal_Mid_R	−0.219	0.1
		Rectus_L	−0.181	0.2
	Left thalamus	Parietal_Sup_L	0.036	0.8
		Temporal_Pole_Mid_R	−0.364	0.009
		Rectus_L	−0.113	0.4
		Temporal_Pole_Mid_L	−0.229	0.035

Frontal_Sup_Medial_R = right medial superior frontal area; ParaHippocampal_R = right parahippocampal area; Parietal_Sup_L = left superior parietal area; PSG = polysomnography; Rectus_L = left rectus; Temporal_Mid_R = right middle temporal area; Temporal_Pole_Mid_L = left middle temporal pole; Temporal_Pole_Mid_R = right middle temporal pole.
We performed the partial correlation analysis between sleep efficiency from PSG and thalamocortical connectivity after controlling for age, sex and educational level.