Altered Effective Connectivity of Children and Young Adults With Unilateral Amblyopia: A Resting-State Functional Magnetic Resonance Imaging Study

Functional consequences of amblyopia and its impact on health-related quality of life

Amblyopia (lazy eye) is the most common cause of monocular vision loss, affecting up to 4% of children and often persisting into adulthood. While treating the visual acuity deficit is often the focus of treatment, there is a pressing need for researchers, educators, and clinicians to understand the effects of amblyopia that extend beyond visual acuity. This review article highlights recent advances in understanding the impact of amblyopia on everyday life functioning. Amblyopia can significantly interfere with contrast sensitivity, attention, reading, eye-hand coordination, body composition, physical activity, and health-related quality of life. A deeper understanding of the functional consequences of amblyopia can be applied to patient management and inform amblyopia treatment, as well as support research into more effective interventions to prevent or rehabilitate deficits that can hinder children's physical, social, and academic success.

Static and temporal dynamic changes in brain activity in patients with post-stroke balance dysfunction: a pilot resting state fMRI

Objective

The aim of this study was to investigate the characteristics of brain activity changes in patients with post-stroke balance dysfunction and their relationship with clinical assessment, and to construct a classification model based on the extreme Gradient Boosting (XGBoost) algorithm to discriminate between stroke patients and healthy controls (HCs).

Methods

In the current study, twenty-six patients with post-stroke balance dysfunction and twenty-four HCs were examined by resting-state functional magnetic resonance imaging (rs-fMRI). Static amplitude of low frequency fluctuation (sALFF), static fractional ALFF (sfALFF), static regional homogeneity (sReHo), dynamic ALFF (dALFF), dynamic fALFF (dfALFF) and dynamic ReHo (dReHo) values were calculated and compared between the two groups. The values of the imaging metrics for the brain regions with significant differences were used in Pearson correlation analyses with the Berg Balance Scale (BBS) scores and as features in the construction of the XGBoost model.

Results

Compared to HCs, the brain regions with significant functional abnormalities in patients with post-stroke balance dysfunction were mainly involved bilateral insula, right fusiform gyrus, right lingual gyrus, left thalamus, left inferior occipital gyrus, left inferior temporal gyrus, right calcarine fissure and surrounding cortex, left precuneus, right median cingulate and paracingulate gyri, right anterior cingulate and paracingulate gyri, bilateral supplementary motor area, right putamen, and left cerebellar crus II. XGBoost results show that the model constructed based on static imaging features has the best classification prediction performance.

Conclusion

In conclusion, this study provided evidence of functional abnormalities in local brain regions in patients with post-stroke balance dysfunction. The results suggested that the abnormal brain regions were mainly related to visual processing, motor execution, motor coordination, sensorimotor control and cognitive function, which contributed to our understanding of the neuropathological mechanisms of post-stroke balance dysfunction. XGBoost is a promising machine learning method to explore these changes.

Altered spontaneous brain activity in children with deprivation amblyopia: a resting-state functional magnetic resonance imaging study

BACKGROUND

To investigate the alterations in spontaneous brain activity and the similarities and differences between monocular deprivation amblyopia and binocular deprivation amblyopia.

METHODS

Twenty children with binocular deprivation amblyopia, 26 children with monocular deprivation amblyopia and 20 healthy controls underwent resting-state functional magnetic resonance imaging. The evaluation of altered spontaneous brain activity was conducted using fractional amplitude of low-frequency fluctuations (fALFF). One-way analysis of variance was employed to analyze fALFF values among the three groups. Additionally, the relationship between fALFF values and best corrected visual acuity (BCVA) was analyzed via correlation analysis.

RESULTS

Compared to healthy controls, children with binocular deprivation amblyopia presented increased fALFF values in the left medial superior frontal gyrus, left middle frontal gyrus, left anterior cingulate cortex, left postcentral gyrus and bilateral precentral gyrus, and decreased fALFF values in the right fusiform gyrus. Compared to healthy controls, children with monocular deprivation amblyopia presented increased fALFF values in the right lingual gyrus, right superior frontal gyrus, right middle frontal gyrus, left superior temporal gyrus, triangular part of the left inferior frontal gyrus and bilateral middle temporal gyrus, and decreased fALFF values in the right precuneus. Compared with monocular deprivation amblyopia, fALFF values of binocular deprivation amblyopia were decreased in the triangular part of the left inferior frontal gyrus, right lingual gyrus and right cuneus, and increased in the left precentral gyrus and left postcentral gyrus. No significant correlations were found between the fALFF values of identified regions and the BCVA of amblyopic eyes for either type of amblyopia.

CONCLUSIONS

Children with deprivation amblyopia presented alterations in spontaneous activity in multiple brain regions, and these alterations differed between monocular amblyopia and binocular amblyopia. These abnormal spontaneous activities may reflect dysfunctions and compensation related to amblyopia.

Altered Brain Functional and Effective Connectivity Induced by Electroacupuncture in Rats Following Anterior Cruciate Ligament Transection

Background

The chronic pain arising from knee osteoarthritis (KOA) is a prevalent clinical manifestation. As a traditional Chinese approach, electroacupuncture (EA) has a positive influence in relieving chronic pain from KOA. The study aims to explore functional connectivity (FC) and effective connectivity (EC) alterations induced by EA in anterior cruciate ligament transection (ACLT) rat model of KOA using resting-state functional magnetic resonance imaging (fMRI).

Methods

After the establishment of ACLT, rats were randomly divided into the EA group and the sham-EA group. The EA group received EA intervention while the sham-EA group received sham-intervention for 3 weeks. Mechanical pain threshold (MPT) assessment was performed before and after intervention, and fMRI was conducted after intervention.

Results

EA intervention effectively relieved pain in post-ACLT rats. Results of rest-state functional connectivity (rs-FC) analysis revealed that compared with the sham-EA group, the EA group had higher FC between the right raphe and the left auditory cortex, the left caudate_ putamen and the left internal capsule (IC), as well as the right zona incerta (ZI) and the left piriform cortex, but lower FC between the right raphe and the left hippocampus ventral, as well as the right septum and the left septum. Furthermore, Granger causality analysis (GCA) found the altered EC between the right septum and the left septum, as well as the left IC and the right septum.

Conclusion

The results confirmed the effect of EA on analgesia in post- ACLT rats. The alterations of FC and EC, mainly involving basal ganglia and limbic system neural connections, might be one of the neural mechanisms underlying the effect of EA, providing novel information about connectomics plasticity of EA following ACLT.

Deficits of the "Good" Eye in Amblyopia: Processing Geometric Properties

Purpose

Although fellow eyes of amblyopia are typically considered normal, recent studies have revealed impairments in certain aspects of vision. However, it remains unclear at which level of object processing these impairments occur. This study aims to investigate the functional level of visual perception impairment in the fellow eye of children and adults with amblyopia using the geometric functional hierarchy discrimination task based on Klein Mathematics methodology.

Methods

Seventy-six patients with amblyopia (40 children and 36 adults) and 77 age-matched healthy controls (40 children and 37 adults) were recruited for this study. The participants completed four sets of geometric hierarchies (in ascending order of stability: Euclidean, affine, projective, and topology) and one set of color discrimination tasks. They were instructed to rapidly and accurately select a distinct shape from the four quadrants.

Results

The participants' performance was evaluated using the inverse efficiency (IE) score (IE = response time (RT)/accuracy). The results of IEs show that the fellow eye of children with amblyopia exhibits normal topological processing, yet displays higher IEs in other geometric properties and color processing, suggesting impairments in these specific discrimination abilities. However, adults with amblyopia did not show deficits on any discrimination types compared with adult controls.

Conclusions

The lack of compromised topological processing suggests that amblyopia may not have inflicted any damage to the subcortical visual pathways. Furthermore, these deficits observed in the fellow eye tend to diminish significantly during adulthood, implying that amblyopia may potentially hinder the maturation process of the fellow eye.

Resting-State Functional Connectivity of the Primary Visual Cortex in Children with Anisometropia Amblyopia

INTRODUCTION

This study aimed to explore the functional connectivity of the primary visual cortex (V1) in children with anisometropic amblyopia by using the resting-state functional connectivity analysis method and determine whether anisometropic amblyopia is associated with changes in brain function.

METHODS

Functional magnetic resonance imaging (fMRI) data were obtained from 16 children with anisometropia amblyopia (CAA group) and 12 healthy children (HC group) during the resting state. The Brodmann area 17 (BA17) was used as the region of interest, and the functional connection (FC) of V1 was analyzed in both groups. A two-sample t test was used to analyze the FC value between the two groups. Pearson's correlation was used to analyze the correlation between the mean FC value in the brain function change area of the CAA group and the best corrected visual acuity (BCVA) of amblyopia. p < 0.05 was considered statistically significant.

RESULTS

There were no significant differences in age and sex between the CAA and HC groups (p > 0.05). Compared to the HC group, the CAA group showed lower FC values in BA17 and the left medial frontal gyrus, as well as BA17 and the left triangle inferior frontal gyrus. Conversely, the CAA group showed higher FC values in BA17 and the left central posterior gyrus. Notably, BCVA in amblyopia did not correlate with the area of change in mean FC in the brain function of the CAA group.

CONCLUSION

Resting-state fMRI-based functional connectivity analysis indicates a significant alteration in V1 of children with anisometropic amblyopia. These findings contribute additional insights into the neuropathological mechanisms underlying visual impairment in anisometropic amblyopia.

Altered local spontaneous brain activity pattern in children with right-eye amblyopia of varying degrees: evidence from fMRI

PURPOSE

To investigate the abnormal changes of local brain activity in children with right-eye amblyopia of varying degrees.

METHODS

Data of resting-state functional magnetic resonance imaging were collected from 16 children with severe amblyopia, 17 children with mild to moderate amblyopia, and 15 children with normal binocular vision. Local brain activity was analyzed using the amplitude of low-frequency fluctuations (ALFF) and regional homogeneity (ReHo).

RESULTS

There were extensive ALFF differences among the three groups in 10 brain regions. There were extensive differences in ReHo among the three groups in 11 brain regions. The ALFF and ReHo of the right orbital part of the middle frontal gyrus displayed a significantly positive correlation with the best-corrected visual acuity of the right eye, respectively. The ALFF value and ReHo value of the right orbital part of the middle frontal gyrus followed the pattern of normal control < mild to moderate amblyopia < severe amblyopia.

CONCLUSION

This study demonstrated that there were changes in specific patterns of ALFF and ReHo in children with right-eye amblyopia of different degrees in brain regions performing visual sensorimotor and attentional control functions.

Long-term effects of early/late-onset visual deprivation on macular and retinal nerve fibers layer structure: A pilot study

BACKGROUND/AIMS

Tomographic analysis of macular and peripapillary retinal nerve fibers layer (RNFL) thickness in patients with history of congenital (CC) and developmental cataract (DC).

METHODS

Analysis of macular and RNFL thickness using a spectral-domain optical coherence tomography was performed. Retinal layers thickness was measured using the internal segmentation software. Measurements of affected (unilateral and bilateral), contralateral eyes and control eyes were compared.

RESULTS

Patients with history of CC or DC (n = 13 and 11 respectively) and 35 healthy control subjects were enrolled. Thicker inner and outer nuclear layers (INL, ONL) and thicker ONL were found when CC and DC group when compared to controls respectively. Bilateral CC showed the most relevant differences. Slight thickening of CC inner retinal layers were found when compared to DC. Increased superonasal RNFL thickness was found in CC group when compared to DC and controls. Thickening of RNFL of contralateral unaffected eyes of unilateral CC were found when compared to controls.

CONCLUSION

Significant macular and RNFL thickness changes between CC, DC patients and controls that partially involve also contralateral unaffected eyes of unilateral congenital cataract were found. CC and DC groups show significant differences only in inner retinal layers thickness. Our data suggest that early visual deprivation may influence retinal arrangements occurring during development involving predominantly the outer nuclear layer and para/perifoveal inner retinal layers, and confirm that early treatment of CC allow to achieve better long-term visual outcome. Moreover functional and structural data support the hypothesis that unilateral amblyopia is not exclusively an unilateral issue.

Amblyopia: progress and promise of functional magnetic resonance imaging

Amblyopia is a neurodevelopmental disorder characterized by functional deficits in the visual cortex. Functional magnetic resonance imaging (fMRI) is the most commonly used neuroimaging technique for investigating amblyopia. Herein, we systematically searched a PubMed database from inception to December 2021 to highlight the current progress and promises about fMRI technology in amblyopia; amblyopia's neural mechanism, the comparison of different types of amblyopia, and the evaluation of the therapeutic effect were explored. Relevant articles published in English and appropriate cross-references were considered for inclusion, including basic studies, imaging techniques, clinical diagnostic and therapeutic studies, case series, and reviews.

[Abnormal spontaneous brain functional activity in adult patients with amblyopia: a resting-state functional magnetic resonance imaging study]

Amblyopia is a visual development deficit caused by abnormal visual experience in early life, mainly manifesting as defected visual acuity and binocular visual impairment, which is considered to reflect abnormal development of the brain rather than organic lesions of the eye. Previous studies have reported abnormal spontaneous brain activity in patients with amblyopia. However, the location of abnormal spontaneous activity in patients with amblyopia and the association between abnormal brain function activity and clinical deficits remain unclear. The purpose of this study is to analyze spontaneous brain functional activity abnormalities in patients with amblyopia and their associations with clinical defects using resting-state functional magnetic resonance imaging (fMRI) data. In this study, 31 patients with amblyopia and 31 healthy controls were enrolled for resting-state fMRI scanning. The results showed that spontaneous activity in the right angular gyrus, left posterior cerebellum, and left cingulate gyrus were significantly lower in patients with amblyopia than in controls, and spontaneous activity in the right middle temporal gyrus was significantly higher in patients with amblyopia. In addition, the spontaneous activity of the left cerebellum in patients with amblyopia was negatively associated with the best-corrected visual acuity of the amblyopic eye, and the spontaneous activity of the right middle temporal gyrus was positively associated with the stereoacuity. This study found that adult patients with amblyopia showed abnormal spontaneous activity in the angular gyrus, cerebellum, middle temporal gyrus, and cingulate gyrus. Furthermore, the functional abnormalities in the cerebellum and middle temporal gyrus may be associated with visual acuity defects and stereopsis deficiency in patients with amblyopia. These findings help explain the neural mechanism of amblyopia, thus promoting the improvement of the treatment strategy for amblyopia.

Abnormal effective connectivity in visual cortices underlies stereopsis defects in amblyopia

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Abnormal effective connectivity inherent stereopsis defects in amblyopia was studied.

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A weakened connection from V2v to LO2 relates to stereopsis defects in amblyopia.

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Higher-order visual cortices may serve as key nodes to the stereopsis defects.

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An independent longitudinal dataset was used to validate the obtained results.

The neural basis underlying stereopsis defects in patients with amblyopia remains unclear, which hinders the development of clinical therapy. This study aimed to investigate visual network abnormalities in patients with amblyopia and their associations with stereopsis function. Spectral dynamic causal modeling methods were employed for resting-state functional magnetic resonance imaging data to investigate the effective connectivity (EC) among 14 predefined regions of interest in the dorsal and ventral visual pathways. We adopted two independent datasets, including a cross-sectional and a longitudinal dataset. In the cross-sectional dataset, we compared group differences in EC between 31 patients with amblyopia (mean age: 26.39 years old) and 31 healthy controls (mean age: 25.71 years old) and investigated the association between EC and stereoacuity. In addition, we explored EC changes after perceptual learning in a novel longitudinal dataset including 9 patients with amblyopia (mean age: 15.78 years old). We found consistent evidence from the two datasets indicating that the aberrant EC from V2v to LO2 is crucial for the stereoscopic deficits in the patients with amblyopia: it was weaker in the patients than in the controls, showed a positive linear relationship with the stereoscopic function, and increased after perceptual learning in the patients. In addition, higher-level dorsal (V3d, V3A, and V3B) and ventral areas (LO1 and LO2) were important nodes in the network of abnormal ECs associated with stereoscopic deficits in the patients with amblyopia. Our research provides insights into the neural mechanism underlying stereopsis deficits in patients with amblyopia and provides candidate targets for focused stimulus interventions to enhance the efficacy of clinical treatment for the improvement of stereopsis deficiency.

Efficacy of acupuncture at ghost points combined with fluoxetine in treating depression: A randomized study

BACKGROUND

Depression affects more than 350 million people worldwide. In China, 4.2% (54 million people) of the total population suffers from depression. Psychotherapy has been shown to change cognition, improve personality, and enhance the ability to cope with difficulties and setbacks. While pharmacotherapy can reduce symptoms, it is also associated with adverse reactions and relapse after drug withdrawal. Therefore, there has been an increasing emphasis placed on the use of non-pharmacological therapies for depression. The hypothesis of this study was that acupuncture at ghost points combined with fluoxetine would be more effective than fluoxetine alone for the treatment of depression.

AIM

To investigate the efficacy of acupuncture at ghost points combined with fluoxetine for the treatment of patients with depression.

METHODS

This randomized controlled trial included patients with mild to moderate depression (n = 160). Patients received either acupuncture at ghost points combined with fluoxetine (n = 80) or fluoxetine alone (control group, n = 80). Needles were retained in place for 30 min, 5 times a week; three treatment cycles were administered. The Mann–Whitney U test was used to compare functional magnet resonance imaging parameters, Hamilton depression rating scale (HAMD) scores, and self-rating depression scale (SDS) scores between the acupuncture group and control group.

RESULTS

There were no significant differences in HAMD or SDS scores between the acupuncture group and control group, before or after 4 wk of treatment. The acupuncture group exhibited significantly lower HAMD and SDS scores than the control group after 8 wk of treatment (P < 0.05). The acupuncture group had significantly lower fractional Amplitude of Low Frequency Fluctuations values for the left anterior wedge leaf, left posterior cingulate gyrus, left middle occipital gyrus, and left inferior occipital gyrus after 8 wk. The acupuncture group also had significantly higher values for the right inferior frontal gyrus, right insula, and right hippocampus (P < 0.05). After 8 wk of treatment, the effective rates of the acupuncture and control groups were 51.25% and 36.25%, respectively (P < 0.05).

CONCLUSION

The study results suggest that acupuncture at ghost points combined with fluoxetine is more effective than fluoxetine alone for the treatment of patients with mild to moderate depression.