In age-related macular degeneration (AMD), the processing of fine details in a visual scene, based on a high spatial frequency processing, is impaired, while the processing of global shapes, based on a low spatial frequency processing, is relatively well preserved. The present fMRI study aimed to investigate the residual abilities and functional brain changes of spatial frequency processing in visual scenes in AMD patients. AMD patients and normally sighted elderly participants performed a categorization task using large black and white photographs of scenes (indoors vs. outdoors) filtered in low and high spatial frequencies, and nonfiltered. The study also explored the effect of luminance contrast on the processing of high spatial frequencies. The contrast across scenes was either unmodified or equalized using a root-mean-square contrast normalization in order to increase contrast in high-pass filtered scenes. Performance was lower for high-pass filtered scenes than for low-pass and nonfiltered scenes, for both AMD patients and controls. The deficit for processing high spatial frequencies was more pronounced in AMD patients than in controls and was associated with lower activity for patients than controls not only in the occipital areas dedicated to central and peripheral visual fields but also in a distant cerebral region specialized for scene perception, the parahippocampal place area. Increasing the contrast improved the processing of high spatial frequency content and spurred activation of the occipital cortex for AMD patients. These findings may lead to new perspectives for rehabilitation procedures for AMD patients.

中文翻译：

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与年龄相关的黄斑变性改变了大脑对视觉场景的处理

在年龄相关性黄斑变性 (AMD) 中，基于高空间频率处理的视觉场景中精细细节的处理受损，而基于低空间频率处理的全局形状处理相对完好. 目前的 fMRI 研究旨在调查 AMD 患者视觉场景中空间频率处理的残余能力和脑功能变化。AMD 患者和正常视力的老年参与者使用大型黑白场景照片（室内对比户外）在低和高空间频率中过滤，并且未过滤。该研究还探讨了亮度对比对高空间频率处理的影响。为了增加高通滤波场景中的对比度，场景之间的对比度要么未修改，要么使用均方根对比度归一化进行均衡。对于 AMD 患者和对照组，高通滤波场景的性能低于低通和非滤波场景。处理高空间频率的缺陷在 AMD 患者中比在对照组中更明显，并且与患者相比，不仅在专用于中央和周边视野的枕骨区域，而且在专门用于场景感知的远处大脑区域，患者的活动低于对照组，海马旁区域。增加对比度改善了 AMD 患者对高空间频率内容的处理并刺激了枕叶皮层的激活。这些发现可能会为 AMD 患者的康复程序带来新的视角。