Thomas Neil W D, Paré Martin
Neuroscience Graduate Program, Centre for Neuroscience Studies, Queen's University, Kingston, Ontario K7L 3N6, Canada.
J Neurophysiol. 2007 Jan;97(1):942-7. doi: 10.1152/jn.00413.2006. Epub 2006 Nov 1.
We studied whether the lateral intraparietal (LIP) area-a subdivision of parietal cortex anatomically interposed between visual cortical areas and saccade executive centers-contains neurons with activity patterns sufficient to contribute to the active process of selecting saccade targets in visual search. Visually responsive neurons were recorded while monkeys searched for a color-different target presented concurrently with seven distractors evenly distributed in a circular search array. We found that LIP neurons initially responded indiscriminately to the presentation of a visual stimulus in their response fields, regardless of its feature and identity. Their activation nevertheless evolved to signal the search target before saccade initiation: an ideal observer could reliably discriminate the target from the individual activation of 60% of neurons, on average, 138 ms after stimulus presentation and 26 ms before saccade initiation. Importantly, the timing of LIP neuronal discrimination varied proportionally with reaction times. These findings suggest that LIP activity reflects the selection of both the search target and the targeting saccade during active visual search.
我们研究了顶叶内侧区（LIP）——顶叶皮层的一个细分区域，在解剖学上介于视觉皮层区域和扫视执行中心之间——是否包含具有足以有助于在视觉搜索中选择扫视目标的活动模式的神经元。在猴子搜索与均匀分布在圆形搜索阵列中的七个干扰物同时呈现的颜色不同的目标时，记录视觉反应神经元。我们发现，LIP神经元最初对其反应视野中视觉刺激的呈现不加区分地做出反应，无论其特征和身份如何。然而，它们的激活在扫视开始前逐渐演变为信号搜索目标：一个理想的观察者平均在刺激呈现后138毫秒和扫视开始前26毫秒，能够可靠地从60%的神经元的个体激活中辨别出目标。重要的是，LIP神经元辨别的时间与反应时间成比例变化。这些发现表明，LIP活动反映了主动视觉搜索过程中搜索目标和目标扫视的选择。
