Enabling global processing in simultanagnosia by psychophysical biasing of visual pathways.
Enabling global processing in simultanagnosia by psychophysical biasing of visual pathways.
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DOI：
10.1093/brain/aws066
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发表时间：
2012-05
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通讯作者：
Cibu Thomas;K. Kveraga;E. Huberle;H. Karnath;M. Bar
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文献类型：
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作者：
Cibu Thomas;K. Kveraga;E. Huberle;H. Karnath;M. Bar
视觉认知的一个基本方面是我们倾向于看到“树木之前的森林”。然而，后顶叶皮层（背侧视觉通路上的一个关键脑区沿着）的损伤会产生一种神经系统疾病，称为失认症，其特征是无法感知“森林”而不是“树木”（即尽管局部处理完好，但整体处理受损）。尽管这些患者的腹侧视觉通路（主要识别通路）是完整的，但这种对整体形状的感知障碍仍然存在。在这里，我们启用全球处理与失认症患者使用的心理物理技术，这使我们能够偏置刺激，使他们主要是由完整的腹侧视觉通路处理。我们的研究结果表明，在全球处理的特点失认症的损害源于通过背侧通路的低空间频率的处理中断。这些发现促进了我们对视觉空间注意和知觉之间关系的理解，并揭示了调节“先看森林后看树木”倾向的神经机制。
A fundamental aspect of visual cognition is our disposition to see the 'forest before the trees'. However, damage to the posterior parietal cortex, a critical brain region along the dorsal visual pathway, can produce a neurological disorder called simultanagnosia, characterized by a debilitating inability to perceive the 'forest' but not the 'trees' (i.e. impaired global processing despite intact local processing). This impairment in perceiving the global shape persists even though the ventral visual pathway, the primary recognition pathway, is intact in these patients. Here, we enabled global processing in patients with simultanagnosia using a psychophysical technique, which allowed us to bias stimuli such that they are processed predominantly by the intact ventral visual pathway. Our findings reveal that the impairment in global processing that characterizes simultanagnosia stems from a disruption in the processing of low-spatial frequencies through the dorsal pathway. These findings advance our understanding of the relationship between visuospatial attention and perception and reveal the neural mechanism mediating the disposition to see the 'forest before the trees'.