Spatial extinction on double asynchronous stimulation
Spatial extinction on double asynchronous stimulation
复制标题
双异步刺激的空间消光
DOI：
10.1016/s0028-3932(97)00044-4
复制
发表时间：
1997
期刊：
影响因子：
2.6
通讯作者：
F. Frassinetti
中科院分区：
文献类型：
--
作者：
G. Pellegrino;G. Basso;F. Frassinetti
尽管视觉消退被广泛认为是一种基于空间的选择性注意障碍，但关于其致病机制的本质，理论上几乎没有共识。一个特定的中断的能力，脱离注意同病灶的刺激，或损失的重量与contralesional对象竞争视觉选择，已被假设为占障碍。我们在一个右半球损伤的病人身上检验了这两种解释的优点。FB，只有当对侧病灶与同侧病灶同时显示时（即视觉消退），才无法识别对侧病灶。他的任务是报告两个目标字母，这两个字母在注视点的左边和右边快速连续出现。刺激呈现的顺序（左优先vs右优先）和靶间间隔（刺激起始时间）是系统变化的。我们发现，对侧病灶消退可能会发生连续呈现的目标，而不仅仅是在同一时间显示的刺激。最重要的是，FB是严重的，同样受损，在处理一个contralesional刺激时，这要么之前的isilesional刺激或随后的间隔小于约600毫秒。这些数据似乎与脱离假设相矛盾，脱离假设预测当刺激首先显示到空间的受损侧时，灭绝会大幅减少。我们认为，视觉选择性注意的竞争模型非常符合数据。
Despite the fact that visual extinction is widely considered a space-based disturbance of selective attention, there has been little theoretical consensus about the nature of its pathogenic mechanism. A specific disruption in the ability to disengage attention from ipsilesional stimuli, or a loss of weight with which contralesional objects compete for visual selection, have been hypothesized to account for the disorder. We tested the merits of these two explanations in a right-hemisphere-lesioned patient. FB, who failed to recognize a contralesional target only when it was shown concurrently to an ipsilesional target (i.e. visual extinction). His task was to report two target letters presented in rapid succession to the left and right of the fixation point. The order of stimulus presentation (Left-First vs Right-First), and the intertarget interval (stimulus onset asynchrony) were varied systematically. We showed that contralesional extinction may occur for successively presented targets, not just for stimuli displayed at the same time. Of most importance, FB was seriously and equally impaired in dealing with a contralesional stimulus when this either preceded the ipsilesional stimulus or followed it by an interval less than about 600 msec. The data appear to contradict the disengagement hypothesis, which predicted a substantial reduction of extinction when a stimulus was displayed first into the lesioned side of space. We suggest that a competitive model of visual selective attention fits the data quite well.