Altered functional connectivity of the thalamus in primary angle-closure glaucoma patients: A resting-state fMRI study

Abstract

Background and objectivesGlaucoma is one of the leading irreversible causes of blindness worldwide, and previous studies have shown that there is abnormal functional connectivity (FC) in the visual cortex of glaucoma patients. The thalamus is a relay nucleus for visual signals; however, it is not yet clear how the FC of the thalamus is altered in glaucoma. This study investigated the alterations in thalamic FC in patients with primary angle-closure glaucoma (PACG) by using resting-state functional MRI (rs-fMRI). We hypothesized that PACG patients have abnormal FC between the thalamus and visual as well as extravisual brain regions.MethodsClinically confirmed PACG patients and age- and gender-matched healthy controls (HCs) were evaluated by T1 anatomical and functional MRI on a 3 T scanner. Thirty-four PACG patients and 33 HCs were included in the rs-fMRI analysis. All PACG patients underwent complete ophthalmological examinations; included retinal nerve fiber layer thickness (RNFLT), intraocular pressure (IOP), average cup-to-disc ratio (A-C/D), and vertical cup-to-disc ratio (V-C/D). After the MRI data were preprocessed, the bilateral thalamus was chosen as the seed point; and the differences in resting-state FC between groups were evaluated. The brain regions that significantly differed between PACG patients and HCs were identified, and the correlations were then evaluated between the FC coefficients of these regions and clinical variables.ResultsCompared with the HCs, the PACG patients showed decreased FC between the bilateral thalamus and right transverse temporal gyrus, between the bilateral thalamus and left anterior cingulate cortex, and between the left thalamus and left insula. Concurrently, increased FC was found between the bilateral thalamus and left superior frontal gyrus in PACG patients. The FC between the bilateral thalamus and left superior frontal gyrus was positively correlated with RNFLT and negatively correlated with the A-C/D and V-C/D. The FC between the left thalamus and left insula was negatively correlated with IOP.ConclusionExtensive abnormal resting-state functional connections between the thalamus and visual and extravisual brain areas were found in PACG patients, and there were certain correlations with clinical variables, suggesting that abnormal thalamic FC plays an important role in the progression of PACG.

Altered static and dynamic functional network connectivity in Primary angle-closure glaucoma patients

“…While the primary auditory cortex is chie y responsible for encoding auditory stimulus attributes, the secondary auditory cortex synthesizes and links this information, creating a speci c perception 42 . Although hearing loss is not a major clinical symptom of PACG, previous studies have identi ed auditory dysfunction in PACG patients 9,43 . In addition, the cognitive and functional deterioration of the individual were tied not just to the loss of auditory and visual capabilities, but also to dual de ciency 44 .…”

“…Resting-state functional connectivity (RS-FC), an analytical approach investigating statistical correlations among signals emanating from either entire or localized brain regions, demonstrates signi cant promise in elucidating synchronous brain activity. Wang et al 9 found extensive abnormal rs-FC between the thalamus and visual and extravisual brain areas. Tong et al 10 demonstrated that there is disturbed interhemispheric resting-state functional connectivity in the vision-related brain areas of individuals with PACG.…”

Altered static and dynamic functional network connectivity in primary angle-closure glaucoma patients

“…Resting-state functional connectivity (RS-FC), an analytical approach investigating statistical correlations among signals emanating from either entire or localized brain regions, demonstrates significant promise in elucidating synchronous brain activity. Wang et al 9 found extensive abnormal rs-FC between the thalamus and visual and extravisual brain areas. Tong et al 10 demonstrated that there is disturbed interhemispheric resting-state functional connectivity in the vision-related brain areas of individuals with PACG.…”

Spontaneous changes in brain network centrality in patients with pathological myopia: A voxel‐wise degree centrality analysis

“…The voxel‐based degree centrality (DC) method is a data analysis method derived from the graph theory approach that allows direct assessment of whole brain network connectivity without a priori assumptions 12 . This method has been successfully applied to the research of various ophthalmic diseases, including exophthalmos of primary hyperthyroidism, ophthalmectomy, diabetic nephropathy, diabetic retinopathy, comitant exotropia strabismus, open globe injury, monocular blindness, and primary angle‐closure glaucoma 13–19 . We illustrate the results of these diseases in Figure 1.…”

“…12 This method has been successfully applied to the research of various ophthalmic diseases, including exophthalmos of primary hyperthyroidism, ophthalmectomy, diabetic nephropathy, diabetic retinopathy, comitant exotropia strabismus, open globe injury, monocular blindness, and primary angle-closure glaucoma. [13][14][15][16][17][18][19] F I G U R E 1 DC method applied in ophthalmological diseases. BAC, bilateral anterior cingulate; BC, bilateral cuneus; BLL, bilateral lingual lobe; BMFG, bilateral medial frontal gyrus; BP, bilateral precuneus; BV1/V2, bilateral primary visual cortex; BVC, bilateral visual cortices; The inclusion criteria for the patients were as follows: (i) binocular diopter of −6.00 to −7.00, and absence of other eye diseases;…”