An Resting-state FMRI Study On Changes Of Brain Functional Connectivity Density In Children With Anisometropic Amblyopia

Purpose:Amblyopia is a developmental disorder resulting from anomalous binocular vis-ual input in early life. Task-based neuroimaging studies have widely investigated cor-tical functional impairments in amblyopia, but changes in spontaneous neuronal func-tional activities in amblyopia remain largely unknown. The present study aimed to detect the changes of cortical functional connectivities in children with anisometropic amblyopia during resting-state. It may provide another evidence for abnormal spon-taneous brain activities in amblyopia.Subjects and Methods:Sixteen right-handed children with anisometropic amblyopia (AAC,5-15years) and11age-and gender-matched right-handed normal sighted children (NSC,5-15years) participated in this study. After excluding2patients and2healthy controls due to excessive head motion during scanning,14AAC (11males,3females; age:9.6±2.9years) and9NSC (6males,3females; age:11.3±2.9years) remained in this study finally. Functional connectivity density (FCD) mapping, an ultrafast data-driven method based on fMRI, combined with seed-based resting-state functional connectiv-ity (rsFC) analysis were applied for the first time to investigate changes in cortical functional connectivities in amblyopia in present study. First, both short-and long-range FCD in the brains of11children with anisometropic amblyopia and9normal sighted children were quantified. Then, group comparisons were conducted to investigate the differences of the short-and long-range FCD of the AAC and NSC at voxel-level and regions of interest (ROIs). Next, the rsFC patterns of seed from each ROI of long-range FCD were computed in the AAC and NSC groups, respectively, and between-group comparison were also conducted. Finally, the correlation of short-/long-range FCD/rsFC in each ROI and the distance visual acuity of the affected eye in the AAC group were evaluated with partial correlation analysis. Results:In contrast to the NSC, the AAC showed significantly decreased short-range FCD in the inferior temporal/fusiform gyri, parieto-occipital and rostrolateral pre-frontal cortices, as well as decreased long-range FCD in the premotor cortex, dorsal inferior parietal lobule, frontal-insular and dorsal prefrontal cortices. Furthermore, most regions with reduced long-range FCD in the AAC showed decreased rsFCwith occipital and posterior parietal cortices in the AAC. Only the short-range FCD in the ROI of rostrolateral prefrontal cortex was found positively correlated with the dis-tance visual acuity of the affected eye in the AAC group.Summary:Chronically poor visual input in anisometropic amblyopia impairs the brain’s short-range functional connections of visual pathways and the frontal cogni-tion-related areas in AAC, which may be one of the main neuromechanism of the common perceptual defects in object recognition and visuospatial processing in am-blyopia. It also impairs the long-range functional connections of the premotor cortex, dorsal inferior parietal lobule and frontal-insular cortex in AAC, which may results in functional abnormalities in visuomotor or visual-guided actions, visuospatial attention modulation and the integration of salient information in amblyopia. It provides evi-dence that spontaneous functional connections in the AAC were significantly im-paired.