Evidence of cortical thickness reduction and disconnection in high myopia

Novel loci for ocular axial length identified through extreme-phenotype genome-wide association study in Chinese populations

PURPOSE

To investigate genetic loci associated with ocular axial length (AL) in the Chinese population.

METHODS

A genome-wide association study meta-analysis was conducted in totalling 2644 Chinese individuals from 3 cohorts: the Guangzhou cohort (GZ, 537 high myopes and 151 hyperopes), Wenzhou cohort (334 high myopes and 6 hyperopes) and Guangzhou Twin Eye Study (1051 participants with normally distributed AL). Functional mapping was performed to annotate the significant signals, possible tissues and cell types by integrating available multiomics data. Logistic regression models using AL-associated SNPs were constructed to predict three AL status in GZ.

RESULTS

Two novel loci (1q25.2 FAM163A and 7p22.2 SDK1) showed genome-wide significant associations with AL, together explaining 29.63% of AL variance in GZ. The two lead SNPs improved the prediction accuracy for AL status, especially for hyperopes. The frequencies of AL decreasing (less myopic) alleles of the two SNPs were lowest in East Asians as compared with other populations (rs17370084: f EAS=0.03, f EUR=0.24, f AFR=0.05; rs73046501: f EAS=0.06, f EUR=0.07, f AFR=0.20), which was in line with the global distribution of myopia. The cerebral cortex and gamma-aminobutyric acidergic interneurons showed possible functional involvement in myopia development, and the galactose metabolic pathways were significantly enriched.

CONCLUSION

Our study identified two population-specific novel loci for AL, expanding our understanding of the genetic basis of AL and providing evidence for a role of the nervous system and glucose metabolism in myopia pathogenesis.

Unveiling the gut microbiota and metabolite profiles in guinea pigs with form deprivation myopia through 16S rRNA gene sequencing and untargeted metabolomics

Aim

The aim of this study was to confirm the presence of the form deprivation myopia (FDM) guinea pig eye-gut axis and investigate the relationship between serum vasoactive intestinal peptide (VIP), lipopolysaccharides (LPS), specific gut microbiota and their metabolites.

Method

20 specific-pathogen-free (SPF) guinea pigs were divided into the FDM and the control(Con) group. Following model induction, serum levels of VIP and LPS were quantified. A combination of 16S ribosomal ribosomal Ribonucleic Acid (rRNA) gene sequencing, non-targeted metabolomics and bioinformatics analysis were employed to identify disparities in gut microbiota and metabolites between the two groups of guinea pigs.

Result

Compared to the control group, FDM guinea pigs exhibited a significant trend towards myopia, along with significantly elevated concentrations of LPS and VIP (p < 0.0001). Furthermore, Ruminococcus_albus emerged as the predominant bacterial community enriched in FDM (p < 0.05), and demonstrated positive correlations with 10 metabolites, including l-Glutamic acid, Additionally, Ruminococcus_albus exhibited positive correlations with VIP and LPS levels (p < 0.05).

Conclusion

The findings suggest that the Ruminococcus_Albus and glutamate metabolic pathways play a significant role in myopia development, leading to concurrent alterations in serum VIP and LPS levels in FDM guinea pigs. This underscores the potential of specific gut microbiota and their metabolites as pivotal biomarkers involved in the pathogenesis of myopia.

Effect of exposure to maternal diabetes during pregnancy on offspring's brain cortical thickness and neurocognitive functioning

Little is known about the long-term effects of maternal diabetes during pregnancy (DP), either gestational diabetes or preexisting diabetes (type 1 or type 2), on offspring's brain morphometry and neurocognitive functioning (NCF). This study examined the effect of prenatal exposure to maternal DP on the brain structure and NCF in children between 9 and 10 years of age. This study used cross-sectional neuroimaging and NCF data from the baseline wave of the Adolescent Brain and Cognitive Development® study. Exposure to maternal DP was assigned from the developmental history questionnaire. Differences in the brain cortical thickness (CTh) and five cognitive abilities (executive function, working and episodic memory, processing speed, and language abilities) were examined in diabetes-exposed and diabetes-unexposed children. Linear mixed effect models and generalized linear models were used to adjust for the effect of confounding variables. A total of 9,967 children (718 diabetes-exposed and 9249 unexposed) were included in the analysis. Diabetes-exposed children had lower whole-brain CTh [mean: exposed vs unexposed = 2.725 mm vs 2.732 mm; difference (95%CI): -0.007 mm (-0.013, -0.001)] compared to unexposed children after adjusting for confounding variables. Diabetes-exposed children had lower CTh in most part of the occipital lobe of both hemispheres, right postcentral gyrus, and left superior parietal cortex. Diabetes-exposed children also had lower scores in processing speed task [mean difference (95%CI): -1.7 (-2.8, -0.6)] and total cognition [mean difference (95%CI): -0.6 (-1.2, -0.02)]. Diabetes-exposed children have reduced CTh and NCF during preadolescence, which might have implications for psychomotor development during later life. Prospective studies are needed to confirm our findings.

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

BACKGROUND

Myopia has become a worldwide problem that endangers public health and adds a serious socioeconomic burden. Current research has focused on the pathogenesis and manifestations of pathological myopia (PM). However, few studies have been conducted on the spontaneous activity of the patient's brain.

PURPOSE

To study the potential brain network activity in patients with PM by the degree centrality (DC) method.

MATERIALS AND METHODS

This experiment included 15 PM patients and 15 healthy controls (HCs). Every participant experienced a resting-state functional magnetic resonance imaging (rs-fMRI) scan. Receiver operating characteristic (ROC) curve analysis was used to distinguish between PM patients and HCs. Correlation analysis was used to explore the relationships between mean DC values and clinical performance in different brain regions.

RESULTS

It showed that patients with PM had lower DC values in the right fusiform gyrus (FR) and right cingulate (CAR). The ROC curve was used to indicate the accuracy of the correlation. It showed that in PM group, left best corrected visual acuity (BCVA-L) and right best corrected visual acuity (BCVA-R) were negatively correlated with the DC value of FR.

CONCLUSION

The occurrence of PM is mainly related to the abnormal activity of the fusiform and cingulum. DC value might be used as a biological marker of abnormal brain activity in PM patients.

Exploration of static functional connectivity and dynamic functional connectivity alterations in the primary visual cortex among patients with high myopia via seed-based functional connectivity analysis

Aim

This study was conducted to explore differences in static functional connectivity (sFC) and dynamic functional connectivity (dFC) alteration patterns in the primary visual area (V1) among high myopia (HM) patients and healthy controls (HCs) via seed-based functional connectivity (FC) analysis.

Methods

Resting-state functional magnetic resonance imaging (fMRI) scans were performed on 82 HM patients and 59 HCs who were closely matched for age, sex, and weight. Seed-based FC analysis was performed to identify alterations in the sFC and dFC patterns of the V1 in HM patients and HCs. Associations between mean sFC and dFC signal values and clinical symptoms in distinct brain areas among HM patients were identified via correlation analysis. Static and dynamic changes in brain activity in HM patients were investigated by assessments of sFC and dFC via calculation of the total time series mean and sliding-window analysis.

Results

In the left anterior cingulate gyrus (L-ACG)/left superior parietal gyrus (L-SPG) and left V1, sFC values were significantly greater in HM patients than in HCs. In the L-ACG and right V1, sFC values were also significantly greater in HM patients than in HCs [two-tailed, voxel-level P < 0.01, Gaussian random field (GRF) correction, cluster-level P < 0.05]. In the left calcarine cortex (L-CAL) and left V1, dFC values were significantly lower in HM patients than in HCs. In the right lingual gyrus (R-LING) and right V1, dFC values were also significantly lower in HM patients than in HCs (two-tailed, voxel-level P < 0.01, GRF correction, cluster-level P < 0.05).

Conclusion

Patients with HM exhibited significantly disturbed FC between the V1 and various brain regions, including L-ACG, L-SPG, L-CAL, and R-LING. This disturbance suggests that patients with HM could exhibit impaired cognitive and emotional processing functions, top-down control of visual attention, and visual information processing functions. HM patients and HCs could be distinguished from each other with high accuracy using sFC and dFC variabilities. These findings may help to identify the neural mechanism of decreased visual performance in HM patients.

Altered time-varying local spontaneous brain activity pattern in patients with high myopia: a dynamic amplitude of low-frequency fluctuations study

PURPOSE

To investigate the abnormal time-varying local spontaneous brain activity in patients with high myopia (HM) on the basis of the dynamic amplitude of low-frequency fluctuations (dALFF) approach.

METHODS

Age and gender matching were performed based on resting-state functional magnetic resonance imaging data from 86 HM patients and 87 healthy controls (HCs). Local spontaneous brain activities were evaluated using the time-varying dALFF method. Support vector machine combined with the radial basis function kernel was used for pattern classification analysis.

RESULTS

Inter-group comparison between HCs and HM patients has demonstrated that dALFF variability in the left inferior frontal gyrus (orbital part), left lingual gyrus, right anterior cingulate and paracingulate gyri, and right calcarine fissure and surrounding cortex was decreased in HM patients, while increased in the left thalamus, left paracentral lobule, and left inferior parietal (except supramarginal and angular gyri). Pattern classification between HM patients and HCs displayed a classification accuracy of 85.5%.

CONCLUSION

In this study, the findings mentioned above have suggested the association between local brain activities of HM patients and abnormal variability in brain regions performing visual sensorimotor and attentional control functions. Several useful information has been provided to elucidate the mechanism-related alterations of the myopic nervous system. In addition, the significant role of abnormal dALFF variability has been highlighted to achieve an in-depth comprehension of the pathological alterations and neuroimaging mechanisms in the field of HM.

Cognitive dysfunctions in high myopia: An overview of potential neural morpho-functional mechanisms

Dementia and cognitive impairment (CIM) carry high levels of mortality. Visual impairment (VI) is linked with CIM risk. High myopia (HM) is a chronic disease frequently leading to irreversible blindness. Current opinion has shifted from retinal injury as the cause of HM to the condition being considered an eye-brain disease. However, the pathogenesis of this disease and the manner in which neural structures are damaged are poorly understood. This review comprehensively discusses the relationship between HM, the central nervous system, and CIM, together with the novel concept of three visual pathways, and possible research perspectives.

Exploration of abnormal dynamic spontaneous brain activity in patients with high myopia via dynamic regional homogeneity analysis

Aim

Patients with high myopia (HM) reportedly exhibit changes in functional brain activity, but the mechanism underlying such changes is unclear. This study was conducted to observe differences in dynamic spontaneous brain activity between patients with HM and healthy controls (HCs) via dynamic regional homogeneity (dReHo) analysis.

Methods

Resting-state functional magnetic resonance imaging (rs-fMRI) scans were performed on 82 patients with HM and 59 HCs who were closely matched for age, sex, and weight. The dReHo approach was used to assess local dynamic activity in the human brain. The association between mean dReHo signal values and clinical symptoms in distinct brain areas in patients with HM was determined via correlation analysis.

Results

In the left fusiform gyrus (L-FG), right inferior temporal gyrus (R-ITG), right Rolandic operculum (R-ROL), right postcentral gyrus (R-PoCG), and right precentral gyrus (R-PreCG), dReHo values were significantly greater in patients with HM than in HCs.

Conclusion

Patients with HM have distinct functional changes in various brain regions that mainly include the L-FG, R-ITG, R-ROL, R-PoCG, and R-PreCG. These findings constitute important evidence for the roles of brain networks in the pathophysiological mechanisms of HM and may aid in the diagnosis of HM.

Reorganized Brain Functional Network Topology in Presbycusis

Purpose

Presbycusis is characterized by bilateral sensorineural hearing loss at high frequencies and is often accompanied by cognitive decline. This study aimed to identify the topological reorganization of brain functional network in presbycusis with/without cognitive decline by using graph theory analysis approaches based on resting-state functional magnetic resonance imaging (rs-fMRI).

Methods

Resting-state fMRI scans were obtained from 30 presbycusis patients with cognitive decline, 30 presbycusis patients without cognitive decline, and 50 age-, sex-, and education-matched healthy controls. Graph theory was applied to analyze the topological properties of brain functional networks including global and nodal metrics, modularity, and rich-club organization.

Results

At the global level, the brain functional networks of all participants were found to possess small-world properties. Also, significant group differences in global network metrics were observed among the three groups such as clustering coefficient, characteristic path length, normalized characteristic path length, and small-worldness. At the nodal level, several nodes with abnormal betweenness centrality, degree centrality, nodal efficiency, and nodal local efficiency were detected in presbycusis patients with/without cognitive decline. Changes in intra-modular connections in frontal lobe module and inter-modular connections in prefrontal subcortical lobe module were found in presbycusis patients exposed to modularity analysis. Rich-club nodes were reorganized in presbycusis patients, while the connections among them had no significant group differences.

Conclusion

Presbycusis patients exhibited topological reorganization of the whole-brain functional network, and presbycusis patients with cognitive decline showed more obvious changes in these topological properties than those without cognitive decline. Abnormal changes of these properties in presbycusis patients may compensate for cognitive impairment by mobilizing additional neural resources.

Disrupted Topological Organization of Resting-State Functional Brain Networks in Age-Related Hearing Loss

Purpose

Age-related hearing loss (ARHL), associated with the function of speech perception decreases characterized by bilateral sensorineural hearing loss at high frequencies, has become an increasingly critical public health problem. This study aimed to investigate the topological features of the brain functional network and structural dysfunction of the central nervous system in ARHL using graph theory.

Methods

Forty-six patients with ARHL and forty-five age, sex, and education-matched healthy controls were recruited to undergo a resting-state functional magnetic resonance imaging (fMRI) scan in this study. Graph theory was applied to analyze the topological properties of the functional connectomes by studying the local and global organization of neural networks.

Results

Compared with healthy controls, the patient group showed increased local efficiency (E_loc) and clustering coefficient (C_p) of the small-world network. Besides, the degree centrality (Dc) and nodal efficiency (Ne) values of the left inferior occipital gyrus (IOG) in the patient group showed a decrease in contrast with the healthy control group. In addition, the intra-modular interaction of the occipital lobe module and the inter-modular interaction of the parietal occipital module decreased in the patient group, which was positively correlated with Dc and Ne. The intra-modular interaction of the occipital lobe module decreased in the patient group, which was negatively correlated with the E_loc.

Conclusion

Based on fMRI and graph theory, we indicate the aberrant small-world network topology in ARHL and dysfunctional interaction of the occipital lobe and parietal lobe, emphasizing the importance of dysfunctional left IOG. These results suggest that early diagnosis and treatment of patients with ARHL is necessary, which can avoid the transformation of brain topology and decreased brain function.

Altered Spontaneous Brain Activity Patterns of Meibomian Gland Dysfunction in Severely Obese Population Measured Using the Fractional Amplitude of Low-Frequency Fluctuations

OBJECTIVE

Utilizing the fractional amplitude of low-frequency fluctuations (fALFF) technique, this study sought to correlate spontaneous cerebral abnormalities with the clinical manifestations of meibomian gland dysfunction (MGD) in severely obese (SO) population.

SUBJECTS AND METHODS

Twelve MGD patients in SO population (PATs) (4 males and 8 females) and twelve healthy controls (HCs) (6 males and 6 females) matched by gender and age were enrolled. Every participant underwent resting-state functional magnetic resonance imaging (rs-MRI) scanning. Spontaneous cerebral activity alterations were examined using the fALFF method. Receiver operating characteristic (ROC) curves were utilized to classify the medial fALFF values of the PATs and HCs. PATs were also asked to complete anxiety and depression score forms, permitting a correlation analysis.

RESULTS

In contrast with HCs, PATs had prominently increased fALFF values in the left lingual gyrus, the right globus pallidus, the right anterior cingulate and paracingulate gyri and the left middle occipital lobe (P < 0.05), and decreased fALFF values in the right cerebellum, the left fusiform gyrus, the right medial orbitofrontal gyrus, the left triangle inferior frontal gyrus and the left inferior parietal gyrus (P < 0.05). The results of the ROC curve indicated that changes in regional fALFF values might help diagnose MGD in SO population. Moreover, fALFF values in the right cerebellum of PATs were positively correlated with hospital anxiety and depression scores (HADS) (r = 0.723, P = 0.008). The fALFF values in the left triangle inferior frontal gyrus of PAT were negatively correlated with HADS (r = -0.651, P = 0.022).

CONCLUSIONS

Aberrant spontaneous activity was observed in multiple regions of the cerebrum, offering helpful information about the pathology of MGD in SO population. Aberrant fALFF values in these regions likely relates to the latent pathologic mechanisms of anomalous cerebral activities in PATs.

Meridional Anisotropy of Foveal and Peripheral Resolution Acuity in Adults With Emmetropia, Myopia, and Astigmatism

Purpose

To quantify astigmatism-related meridional anisotropy in visual resolution at central, nasal, and inferior visual fields.

Methods

Three groups of young adults (range, 18–30 years) with corrected-to-normal visual acuity (logMAR 0) were recruited: (1) myopic astigmats (MA): spherical-equivalent error (SE) < −0.75D, with-the-rule astigmatism ≥ 2.00D, n = 19; (2) simple myopes (SM): SE < −0.75D, astigmatism ≤ 0.50D, n = 20; and (3) emmetropes (EM): SE ± 0.50D, astigmatism ≤ 0.50D, n = 14. Resolution acuity was measured for the horizontal and vertical gratings at central and peripheral visual fields (eccentricity: 15°) using a 3-down 1-up staircase paradigm. On- and off-axis refractive errors were corrected by ophthalmic lenses.

Results

The MA group exhibited meridional anisotropy preferring vertical gratings. At the central field, the MA group had better resolution acuity for vertical than horizontal gratings, and their resolution acuity for horizontal gratings was significantly worse than the SM and EM groups. At peripheral visual fields, both the SM and EM groups showed better resolution acuity for the radial (i.e., nasal field: horizontal gratings; inferior field: vertical gratings) than tangential orientation. However, the MA group tended to have better resolution acuity for the tangential orientation (i.e., vertical gratings), and their resolution acuity for horizontal gratings was significantly lower than the SM and EM groups at the nasal field. No significant differences were found in the inferior field among the three groups.

Conclusions

This study provided evidence of astigmatism-related meridional anisotropy at the fovea and nasal visual fields, underscoring the significant impact of astigmatism on orientation-dependent visual functions.