Attentional dynamics and visual perception: mechanisms of spatial disorientation in Alzheimer's disease
Attentional dynamics and visual perception: mechanisms of spatial disorientation in Alzheimer's disease
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DOI：
10.1093/brain/awg105
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发表时间：
2003-05-01
期刊：
影响因子：
14.5
通讯作者：
Duffy, CJ
中科院分区：
文献类型：
--
作者：
Kavcic, V;Duffy, CJ
视觉空间定向障碍迫使阿尔茨海默病患者放弃独立活动。我们之前发现，移动和车辆导航的限制与阿尔茨海默病的视觉运动处理受损有关。我们现在假设这些知觉障碍反映了视觉注意力的时间限制。我们评估了14名阿尔茨海默病患者和12名年龄匹配的老年正常对照者的注意力、知觉和神经心理能力。采用快速连续视觉呈现法（RSVP）测量视觉注意的时间动态。利用光流的感知阈值来评估空间定位的视觉处理，即观察者自我运动时看到的视觉运动。阿尔茨海默氏症患者在RSVP过程中表现出夸张的注意力眨眼，识别出两个目标中的第一个，但由于干扰物的数量而忽略了第二个目标。他们还表现出一种独特的注意力掩蔽形式，在这种情况下，他们会错过第一个目标，但会识别第二个目标，这同样取决于干扰物的数量。两种类型的RSVP错误都与阿尔茨海默病患者选择性升高的光流阈值相关。这表明视觉感知的时间限制可能会损害光流分析并导致阿尔茨海默病的空间定向障碍。这些发现与视觉知觉的两阶段模型一致，表明第二阶段的工作记忆机制为第一阶段的特定类别知觉处理器提供了输入的反馈控制。
Visuospatial disorientation forces Alzheimer's disease patients to abandon independent activities. We found previously that limitations of ambulatory and vehicular navigation are linked to impaired visual motion processing in Alzheimer's disease. We now hypothesize that these perceptual impairments reflect temporal constraints on visual attention. We evaluated attentional, perceptual and neuropsychological capacities in 14 Alzheimer's disease patients and 12 age-matched older normal controls. The temporal dynamics of visual attention were measured using rapid serial visual presentation (RSVP) to assess the attentional blink. Visual processing for spatial orientation was assessed using perceptual thresholds for optic flow, the visual motion seen during observer self-movement. Alzheimer's disease patients show an exaggerated attentional blink during RSVP, identifying the first of two targets but missing the second target depending on the number of intervening distractors. They also show a unique form of attentional masking in which they miss the first target but identify the second, again depending on the number of intervening distractors. Both types of RSVP errors are correlated with selectively elevated optic flow thresholds in Alzheimer's disease patients. This suggests that temporal constraints on visual perception might impair optic flow analysis and contribute to spatial disorientation in Alzheimer's disease. These findings are consistent with two-stage models of visual perception, suggesting that the working memory mechanisms in the second stage provide feedback control of input to category-specific perceptual processors in the first stage.