Altered Spontaneous Activity in Anisometropic Amblyopia Subjects: Revealed by Resting-State fMRI

Amblyopia, also known as lazy eye, usually occurs during early childhood and results in poor or blurred vision. Recent neuroimaging studies have found cortical structural/functional abnormalities in amblyopia. However, until now, it was still not known whether the spontaneous activity of the brain changes in amblyopia subjects. In the present study, regional homogeneity (ReHo), a measure of the homogeneity of functional magnetic resonance imaging signals, was used for the first time to investigate changes in resting-state local spontaneous brain activity in individuals with anisometropic amblyopia. Compared with age- and gender-matched subjects with normal vision, the anisometropic amblyopia subjects showed decreased ReHo of spontaneous brain activity in the right precuneus, the left medial prefrontal cortex, the left inferior frontal gyrus, and the left cerebellum, and increased ReHo of spontaneous brain activity was found in the bilateral conjunction area of the postcentral and precentral gyri, the left paracentral lobule, the left superior temporal gyrus, the left fusiform gyrus, the conjunction area of the right insula, putamen and the right middle occipital gyrus. The observed decreases in ReHo may reflect decreased visuo-motor processing ability, and the increases in ReHo in the somatosensory cortices, the motor areas and the auditory area may indicate compensatory plasticity in amblyopia.

弱视（amblyopia），俗称懒眼，通常始发于儿童早期，可导致视力减退或视物模糊。既往神经影像学研究已证实弱视患者存在皮层结构与功能异常。然而截至目前，学界仍未明确弱视受试者的脑自发活动是否存在改变。本研究首次采用局部一致性（regional homogeneity, ReHo）——一种量化功能磁共振成像信号同质性的指标——探究屈光参差性弱视患者的静息态局部脑自发活动变化。与年龄、性别匹配的正常视力对照受试者相比，屈光参差性弱视受试者的右侧楔前叶、左侧内侧前额叶皮层、左侧额下回及左侧小脑的自发脑活动局部一致性显著降低；而双侧中央后回与中央前回联合区、左侧中央旁小叶、左侧颞上回、左侧梭状回、右侧岛叶与壳核联合区以及右侧枕中回的自发脑活动局部一致性则显著升高。本研究观察到的局部一致性降低，或可反映弱视患者视运动处理能力的下降；而躯体感觉皮层、运动区及听觉皮层的局部一致性升高，则提示弱视患者存在代偿性脑可塑性。