Laboratorium voor Neuro- en Psychofysiologie, KU Leuven Medical School, Campus Gasthuisberg, 3000 Leuven, Belgium.
Cereb Cortex. 2010 Oct;20(10):2464-77. doi: 10.1093/cercor/bhp315. Epub 2010 Jan 25.
Searching for an object in a complex visual scene involves selection mechanisms. Generally, it is assumed that efficient "pop-out" search involves mainly bottom-up processing, whereas inefficient search requires pronounced top-down control over visual processing. We used functional magnetic resonance imaging in behaving monkeys to explore the functional network involved in efficient visual search. As a pop-out target automatically attracts spatial attention, we attempted to determine the regions involved in feature selection independently of the spatial allocation of attention. Therefore, monkeys were trained to perform a search task in which they had to covertly detect the presence of a salient target among distractor objects. Three tasks were used to control, as much as possible, for the spatial allocation of attention. These control tasks were matched with the search task for visual input and manual responses. Pop-out search, when compared with the control tasks, activated 3 frontal regions: frontal eye field, area 45, and a posterior portion of area 46, in addition to small activation sites in lateral intraparietal area and inferotemporal area TE. Our results show that efficient search involves frontal regions as much as visual regions and in particular that ventral prefrontal area 45 is involved in top-down control during efficient search.
在复杂的视觉场景中搜索一个物体涉及到选择机制。一般来说，人们认为有效的“突出”搜索主要涉及自下而上的处理，而效率较低的搜索则需要对视觉处理进行明显的自上而下的控制。我们使用功能磁共振成像在行为猴子中探索涉及高效视觉搜索的功能网络。由于突出的目标自动吸引空间注意力，我们试图确定与注意力的空间分配无关的特征选择所涉及的区域。因此，猴子被训练执行一项搜索任务，在该任务中，它们必须在分心物体中 covertly 检测到突出目标的存在。使用了三个任务来尽可能地控制注意力的空间分配。这些控制任务与视觉输入和手动响应的搜索任务相匹配。与控制任务相比，突出搜索激活了 3 个额叶区域：额眼区、45 区和 46 区的后部，以及外侧顶内区和颞下回 TE 的小激活部位。我们的结果表明，有效的搜索涉及到额叶区域和视觉区域，特别是腹侧前额叶 45 区在有效的搜索中涉及到自上而下的控制。
