Altered Functional Connectivity Strength of Primary Visual Cortex in Subjects with Diabetic Retinopathy

Figures & data

Table 1 Scanning Parameters of Structural T1-Weighted Images and BOLD Sequence

Sequence	TE(ms)	TR(ms)	Gap(mm)	Thickness(mm)	FOV(mm^2)	FA	AM	VS(mm^3)
T1WI	3.3	8.5	0	1.0	240×240	12°	256×256	–
BOLD	25	2000	1.2	3.0	240×240	90°	64×64	3.6×3.6×3.6

Abbreviations: T1WI, T1-weighted imaging; BOLD, blood oxygenation level dependent imaging; TR, repetition time; TE, echo time; AM, acquisition matrix; FOV, field of view; FA, flip angle; VS, voxel size.

Figure 1 The center of V1 was chosen as the seed point to calculate FC (the red area).

Abbreviations: FC, functional connectivity; L, left; R, right; V1, primary visual cortex.

Table 2 Demographics and Visual Measurements Among Three Groups

	DR Group	DM Group	HC Group	DR Group/DM Group		DR Group/HC Group
				T-Values	p-values	T-Values	p-values
Gender (male/female)	18/17	10/12	16/22	N/A	N/A	N/A	N/A
Age (years)	53.37±7.56	55.23±7.73	54.46±8.06	−0.576	0.485	−0.545	0.532
Handedness	35 R	22 R	38 R	N/A	N/A	N/A	N/A
Education (years)	11.85±1.47	12.05±2.17	12.20±1.69	−0.354	0.896	−0.335	0.754
BMI (kg/m^2)	23.56±2.43	23.28±2.76	23.02±1.98	1.258	0.187	1.548	0.124
Duration of diabetes (years)	5.52±3.96	5.45±2.65	N/A	1.048	0.654	N/A	N/A
Duration of DR (years)	1.34±0.76	N/A	N/A	N/A	N/A	N/A	N/A
BCVA-OD	0.48±0.28	1.08±0.25	1.16±0.15	−14.963	<0.001	−15.645	<0.001
BCVA-OS	0.43±0.31	1.14±0.18	1.24±0.22	−13.649	<0.001	−12.630	<0.001
Intraocular pressure	15.79±1.37	15.46±2.43	15.12±1.49	1.247	0.573	1.470	0.472
HbA1c (%)	7.25±1.54	7.38±1.68	5.64±0.96	−0.475	0.726	2.690	<0.001
Fasting blood glucose(mmol/L)	7.96±2.45	7.75±2.24	5.75±1.05	−0.568	0.564	3.254	<0.001

Notes: χ2 test for sex (n). Independent t-test for the other normally distributed continuous data (means ± SD).

Abbreviations: DR, diabetic retinopathy; DM, diabetes mellitus; HC, healthy control; N/A, not applicable; BCVA, best corrected visual acuity; OD, oculus dexter; OS, oculus sinister; Hb, glycosylated hemoglobin; BMI, body mass index.

Figure 2 The fundus photos with the typical presentations of DR.

Abbreviations: DR, diabetic retinopathy; OD, oculus dexter; OS, oculus sinister.

Table 3 Significant Differences in the FC of Left V1 Among Three Groups

Brain Areas	MNI Coordinates			Voxels	BA	Peak T Values
	x	y	z
One-way ANOVA
Left OSFG	−24	2	−15	69	-	3.7166
DR vs HC
Bilateral Caudate/Olfactory/OSFG	12	21	−15	939	-	4.5818
Bilateral CAL/ left LING	−3	−72	9	433	17,18	−4.1422
DM vs HC
Left fusiform	−33	−45	−9	140	-	−4.0305
Left superior frontal gyrus	−9	30	36	143	-	3.6485

Notes: The statistical threshold was set at the voxel level with p<0.01 for multiple comparisons using Gaussian random-field theory (two-tailed, voxel-level: p<0.01, GRF correction, cluster-level: p<0.05).

Abbreviations: FC, function connectivity; V1, primary visual cortex; BA, Brodmann area; GRF, Gaussian random field; DR, diabetic retinopathy; DM, diabetes mellitus; HC, healthy control; LING, lingual gyrus; CAL, calcarine; OSFG, orbital superior frontal gyrus; MNI, Montreal Neurological Institute.

Table 4 Significant Differences in the FC of Right V1 Among Three Groups

Brain Areas	MNI Coordinates			Voxels	BA	Peak T Values
	x	y	z
One-way ANOVA
Right OSFG	12	21	−15	263	-	4.3383
Left OSFG	−24	39	−18	182	-	3.8161
DR vs DM
Right CAL	6	−75	12	248	17,18	7.2358
DM vs HC
Bilateral CAL	3	−75	9	1566	17,18	−9.0369
DR vs HC
Bilateral Caudate/Olfactory/OSFG	−24	12	−15	1065	3,4,6	8.798
Bilateral CAL/ left LING	−9	−81	−12	531	17,18	−3.9204

Notes: The statistical threshold was set at the voxel level with p<0.01 for multiple comparisons using Gaussian random-field theory (two-tailed, voxel-level: p<0.01, GRF correction, cluster-level: p<0.05).

Abbreviations: FC, function connectivity; V1, primary visual cortex; BA, Brodmann area; GRF, Gaussian random field; DR, diabetic retinopathy; DM, diabetes mellitus; HC, healthy control; LING, lingual gyrus; CAL, calcarine; OSFG, orbital superior frontal gyrus; MNI, Montreal Neurological Institute.

Figure 3 Distribution group mean zFC among DR, DM and HC group.

Notes: (A) Distribution mean zFC pattern of left V1 in group-level of DR, DM and HC group in the typical frequency band (0.01–0.08 Hz). (B) Distribution mean zFC pattern of right V1 in group-level of DR, DM and HC group in the typical frequency band (0.01–0.08 Hz) (p<0.01).
Abbreviations: FC, functional connectivity; DR, diabetic retinopathy; DM, diabetes mellitus; HC, healthy control; L, left; R, right; V1, primary visual cortex.

Figure 4 Significant zFC maps of left V1 differences among three groups.

Notes: ROI in the left V1. (A) Significant zFC maps of left V1 differences among three groups using one-way ANOVA. (B) Significant zFC maps of left V1 differences between DR and HC groups; (C) Significant zFC maps of left V1 differences between DM and HC groups; (D) Significant zFC maps of left V1 differences between DR and DM groups (voxel-level: p<0.01, GRF correction, cluster-level: p<0.05).
Abbreviations: ROI, region of interest; V1, primary visual cortex; DR, diabetic retinopathy; DM, diabetes mellitus; HC, healthy control; FC, functional connectivity; L, left; R, right; GRF, Gaussian random field.

Figure 5 Significant zFC maps of right V1 differences among three groups.

Notes: ROI in the right V1. (A) Significant zFC maps of right V1 differences among three groups using one-way ANOVA. (B) Significant zFC maps of right V1 differences between DR and HC groups; (C) Significant zFC maps of right V1 differences between DM and HC groups; (D) Significant zFC maps of right V1 differences between DR and DM groups (voxel-level: p<0.01, GRF correction, cluster-level: p<0.05).
Abbreviations: ROI, region of interest; V1, primary visual cortex; DR, diabetic retinopathy; DM, diabetes mellitus; HC, healthy control; FC, functional connectivity; L, left; R, right; GRF, Gaussian random field.