The multiple roles of visual cortical areas MT/MST in remembering the direction of visual motion
The multiple roles of visual cortical areas MT/MST in remembering the direction of visual motion
复制标题
DOI：
10.1093/cercor/10.11.1053
复制
发表时间：
2000-11-01
期刊：
影响因子：
3.7
通讯作者：
Pasternak, T
中科院分区：
文献类型：
--
作者：
Bisley, JW;Pasternak, T
尽管皮质区域 MT 和 MST (MT/MST) 在定向运动信息处理中的作用已得到充分证实，但人们对这些区域如何帮助执行需要使用此类信息的复杂行为任务的方式知之甚少。我们在视觉工作记忆任务中测试了这些区域单侧损伤的猴子，其中运动信号不仅需要被编码，而且还需要存储短暂的时间然后检索。猴子比较了两个随机点刺激（样本和测试）的运动方向，中间有时间延迟。通过增加时间延迟并在空间上分离两种刺激，将一种刺激置于受影响的视野中，另一种置于完整的视野中，我们能够评估 MT/MST 对任务特定组成部分的贡献：编码（样本）、保留（延迟）和编码/检索/比较（测试）。我们发现 MT/MST 损伤对特定成分的影响取决于任务的要求和视觉运动刺激的性质。每当刺激由沿广泛方向移动的随机点组成时，MT/MST 损伤似乎就会影响编码。此外，当病变影响样本的编码时，刺激运动方向的保留也会受到影响。然而，当刺激是连贯的并且任务的重点是比较小的方向差异时，MT/MST 的缺乏会对任务的检索/比较部分产生重大影响，而不是对编码或存储产生重大影响。
Although the role of cortical areas MT and MST (MT/MST) in the processing of directional motion information is well established, little is known about the way these areas contribute to the execution of complex behavioral tasks requiring the use of such information. We tested monkeys with unilateral lesions of these areas on a visual working memory task in which motion signals not only had to be encoded, but also stored for brief periods of time and then retrieved. The monkeys compared the directions of motion of two random dot stimuli, sample and test, separated by a temporal delay. By increasing the temporal delay and spatially separating the two stimuli, placing one in the affected visual field and the other in the intact visual field, we were able to assess the contribution of MT/MST to specific components of the task: encoding (sample), retention (delay) and encoding/retrieval/comparison (test). We found that the effects of MT/MST lesions on specific components depended upon the demands of the task and the nature of the visual motion stimuli. Whenever stimuli consisted of random dots moving in a broad range of directions, MT/MST lesions appeared to affect encoding. Furthermore, when the lesions affected encoding of the sample, retention of the direction of stimulus motion was also affected. However, when the stimulus was coherent and the emphasis of the task was on the comparison of small direction differences, the absence of MT/MST had major impact on the retrieval/comparison component of the task and not on encoding or storage.