斜视性弱视皮层损害的功能性磁共振成像研究

The pathogenetic mechanism of cortical deficit in people with strabismic amblyopia detected by functional MRI

目的 利用血氧水平依赖的功能性磁共振成像 (BOL D- f MRI)技术 ,探讨斜视性弱视的可能机制。 方法 以 1.5 T磁共振成像系统采集 11例斜视性弱视、8例正常人枕叶视皮层 BOL D- f MRI数据 ,比较斜视性弱视组与正常组皮层双眼像素指数以及斜视性弱视组两眼皮层神经元的平均活动水平。 结果 正常组双眼像素指数 :4 7.82 %± 5 .34% ,斜视性弱视组 :14 .13%± 4 .5 5 % ,两组差异有显著性的意义(P<0 .0 5 )。选用高空间频率 (1、2 cycle/ degree)刺激时 ,弱视眼驱使皮层神经元平均活动水平较对侧眼降低 (P<0 .0 5 ) ,余差异无显著性的意义 (P>0 .0 5 )。 结论 斜视性弱视可能与皮层双眼细胞减少以及弱视眼对高空间频率视信息存在采样、编码的异常有关。BOL D- f MRI为深入探讨弱视的神经病理机制提供了新的途径。

Objective To detecte the pathogenetic mechanism of cortical deficit in persons with strabismic amblyopia by blood oxygenation level dependent-functional magnetic resonance imaging (BOLD-fMRI). Methods The data of BOLD-fMRI of occipital visual cortex in 11 persons with strabismic amblyopia and 8 healthy ones were collected by 1.5T MRI system. The results of binocular pixel exponent in strabismic amblyopia group was compared with that in the normal group and the result of and average activation of cortical neuron in strabismic amblyopia group was analyzed. Results The binocular pixel exponent was lower in the strabismic amblyopia group (14.13%±4.55%) than that in the normal group(47.82%±5.34%) ( P <0.05). When stimulated by higher-spatial-frequency the activation is reduced in the strabismic amblyopia eyes, but not in the normal eyes ( P <0.05). Conclusions The reduction of cortical binocular cells and the undersampling and coding of higher-spatial-frequency components of visual stimuli may be related to the strabismic amblyopia. BOLD-fMRI may provide a new path to detecte the pathogenetic mechanism of cortical deficit in people with strabismic amblyopia.