Different target-discrimination times can be followed by the same saccade-initiation timing in different stimulus conditions during visual searches
Different target-discrimination times can be followed by the same saccade-initiation timing in different stimulus conditions during visual searches
复制标题
在视觉搜索过程中，在不同的刺激条件下，不同的目标辨别时间可以跟随相同的扫视启动时间
DOI：
10.1152/jn.00043.2015
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发表时间：
2015
影响因子：
2.5
通讯作者：
Ogawa T
中科院分区：
文献类型：
--
作者：
Tanaka T;Nishida S;Ogawa T
视觉搜索的神经过程可以分为两个阶段：目标识别和眼跳准备/产生。这预示着预辨别阶段的时间长度根据不同刺激条件下的搜索难度而变化，而后辨别阶段的时间长度是刺激不变的。然而，最近的研究表明，不同的刺激条件下的postdiscrimination间隔的长度变化。为了解决视觉刺激是否以及如何影响的postdiscrimination间隔的确定，我们记录了单神经元活动的外侧顶内区（LIP）时，猴子（Macaca fuscata）进行了颜色单例搜索涉及四个刺激条件，不同的亮度（明亮与昏暗）和目标分心物颜色相似性（容易与困难）。我们特别集中在比较活动之间的困难和暗淡容易的条件下，在视觉刺激有很大的不同，但平均反应时间是不可区分的。这使我们能够在不同刺激条件之间的搜索速度差异最小时检查神经元活动。我们发现，不仅prediscrimination，但也postdiscrimination间隔不同的刺激条件下：postdiscrimination间隔较长的暗淡容易的条件下比在困难的条件。进一步的分析表明，postdiscrimination间隔可能会随着刺激亮度而变化。一个计算机模拟使用的累积阈值模型表明，亮度相关的差异，在视觉反应强度的歧视时间可能是不同的postdiscrimination间隔的原因。
The neuronal processes that underlie visual searches can be divided into two stages: target discrimination and saccade preparation/generation. This predicts that the length of time of the prediscrimination stage varies according to the search difficulty across different stimulus conditions, whereas the length of the latter postdiscrimination stage is stimulus invariant. However, recent studies have suggested that the length of the postdiscrimination interval changes with different stimulus conditions. To address whether and how the visual stimulus affects determination of the postdiscrimination interval, we recorded single-neuron activity in the lateral intraparietal area (LIP) when monkeys (Macaca fuscata) performed a color-singleton search involving four stimulus conditions that differed regarding luminance (Bright vs. Dim) and target-distractor color similarity (Easy vs. Difficult). We specifically focused on comparing activities between the Bright-Difficult and Dim-Easy conditions, in which the visual stimuli were considerably different, but the mean reaction times were indistinguishable. This allowed us to examine the neuronal activity when the difference in the degree of search speed between different stimulus conditions was minimal. We found that not only prediscrimination but also postdiscrimination intervals varied across stimulus conditions: the postdiscrimination interval was longer in the Dim-Easy condition than in the Bright-Difficult condition. Further analysis revealed that the postdiscrimination interval might vary with stimulus luminance. A computer simulation using an accumulation-to-threshold model suggested that the luminance-related difference in visual response strength at discrimination time could be the cause of different postdiscrimination intervals.