Schultz Johannes, Lennert Therese
Department of Cognitive and Computational Psychophysics, Max Planck Institute for Biological Cybernetics, Spemannstrasse 38, D-72076 Tübingen, Germany.
Neuroimage. 2009 May 1;45(4):1314-28. doi: 10.1016/j.neuroimage.2009.01.012. Epub 2009 Jan 23.
A lot is known about the neural basis of directing attention based on explicit cues. In real life however, attention shifts are rarely directed by explicit cues but rather generated implicitly, for example on the basis of previous experience with a given situation. Here, we aimed at studying attention shifts dependent on recent trial history. While explicitly cued attention shifts involve activity in cortex of the intraparietal sulcus, whether this region is also involved in shifting attention according to recent history is still unknown. We asked observers to detect targets in a stream of visual stimuli with three feature dimensions: color, shape and motion. Critically, target occurrence probability was always higher in one stimulus dimension than in the others, and probabilities switched between dimensions over blocks of trials. After each probability switch, target detection times decreased exponentially for high-probability targets and increased for low-probability targets, compatible with gradual shifts in attention dependent on trial history since the switch. BOLD signal in left prefrontal and intraparietal sulcus regions was higher in the early phase after the switch, while anterior cingulate, cuneus, precuneus, temporal and more anterior frontal regions showed more activation later after the switch. These findings are compatible with the engagement of regions involved in the establishment and maintenance of attentional sets. BOLD signal in left intraparietal sulcus correlated with the size of the performance changes consecutive to the detected targets, suggesting that it reflects the size of attention shifts induced by updating target probabilities over recent trial history.
关于基于明确线索引导注意力的神经基础，我们已经了解很多。然而在现实生活中，注意力的转移很少由明确线索引导，而是通过内隐方式产生，例如基于对特定情境的既往经验。在此，我们旨在研究依赖于近期试验历史的注意力转移。虽然明确线索引导的注意力转移涉及顶内沟皮质的活动，但该区域是否也参与根据近期历史转移注意力仍不清楚。我们要求观察者在具有颜色、形状和运动三个特征维度的视觉刺激流中检测目标。关键在于，在一个刺激维度中目标出现的概率总是高于其他维度，并且概率在不同试验块之间在各维度间切换。每次概率切换后，高概率目标的目标检测时间呈指数下降，低概率目标的目标检测时间增加，这与自切换以来依赖试验历史的注意力逐渐转移相一致。在切换后的早期阶段，左前额叶和顶内沟区域的血氧水平依赖（BOLD）信号较高，而前扣带回、楔叶、楔前叶、颞叶及更靠前的额叶区域在切换后较晚时显示出更多激活。这些发现与参与注意力集的建立和维持的区域的参与情况相符。左顶内沟的BOLD信号与检测到目标后连续的表现变化大小相关，表明它反映了通过更新近期试验历史中的目标概率所诱导的注意力转移大小。
