Cortical fMRI activation produced by attentive tracking of moving targets
Cortical fMRI activation produced by attentive tracking of moving targets
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DOI：
10.1152/jn.1998.80.5.2657
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发表时间：
1998-11-01
影响因子：
2.5
通讯作者：
Tootell, RBH
中科院分区：
文献类型：
--
作者：
Culham, JC;Brandt, SA;Tootell, RBH
注意力可以用来跟踪移动的物品，特别是当有多个感兴趣的目标不能全部跟随眼球运动时。功能磁共振成像(FMRI)用于研究注意跟踪所涉及的皮质区域。皮质扁平化技术促进了由注意力跟踪、视觉运动、离散注意力转移和眼球运动产生的激活的受试者内比较。在主要任务中，受试者观看了九个绿色“弹跳球”的展示，并在注视时利用注意力在大脑中跟踪其中的一个子集。在每个注意跟踪条件开始时，几个目标球(如3/9)在2个S时变为红色，然后恢复为绿色。然后，受试者使用注意力来跟踪先前指示的目标，否则这些目标与非目标无法区分。当没有目标指示时，注意力跟踪条件和被动观看同一显示器交替进行。受试者接受了眼动监测器的预先测试，以确保他们在凝视时能够准确地完成任务。对于7名受试者，功能激活叠加在每个个体的皮质展开的表面上。注意追踪和被动观察的比较显示，双侧激活在顶叶皮质(顶内沟、中央后沟、顶上小叶和楔前叶)、额叶皮质(额叶眼野和中央前沟)和MT复合体(包括运动选择区MT和MST)。早期视区缺乏注意力增强，MT复合体注意力增强较弱。然而，在顶叶和额叶区域，当仔细跟踪物品时，移动刺激产生的信号变化是原来的两倍多。注意力跟踪和注意力转移之间的比较揭示了本质上相同的激活模式，只是激活的幅度不同。这表明，顶叶皮质不仅参与了不同空间位置的物体之间的离散注意力转移，而且还参与了对移动物体的连续“注意追求”。注意力跟踪激活模式也与眼球运动产生的激活模式相似，尽管不完全相同。综上所述，这些结果表明，注意力跟踪是由负责注意力转移和眼球运动的顶叶和额叶区域以及被认为负责运动感知的MT复合体所调节的区域网络。这些结果与注意力跟踪的理论模型是一致的，注意力跟踪是一种注意过程，为目标分配空间标记并记录其位置的变化，从而产生高水平的明显运动感知。
Attention can be used to keep track of moving items, particularly when there are multiple targets of interest that cannot all be followed with eye movements. Functional magnetic resonance imaging (fMRI) was used to investigate cortical regions involved in attentive tracking. Cortical flattening techniques facilitated within-subject comparisons of activation produced by attentive tracking, visual motion, discrete attention shifts, and eye movements. In the main task, subjects viewed a display of nine green ''bouncing balls'' and used attention to mentally track a subset of them while fixating. At the start of each attentive-tracking condition, several target balls (e.g., 3/9) turned red for 2 s and then reverted to green. Subjects then used attention to keep track of the previously indicated targets, which were otherwise indistinguishable from the nontargets. Attentive-tracking conditions alternated with passive viewing of the same display when no targets had been indicated. Subjects were pretested with an eye-movement monitor to ensure they could perform the task accurately while fixating. For seven subjects, functional activation was superimposed on each individual's cortically unfolded surface. Comparisons between attentive tracking and passive viewing revealed bilateral activation in parietal cortex (intraparietal sulcus, postcentral sulcus, superior parietal lobule, and precuneus), frontal cortex (frontal eye fields and precentral sulcus), and the MT complex (including motion-selective areas MT and MST). Attentional enhancement was absent in early visual areas and weak in the MT complex. However, in parietal and frontal areas, the signal change produced by the moving stimuli was more than doubled when items were tracked attentively. Comparisons between attentive tracking and attention shifting revealed essentially identical activation patterns that differed only in the magnitude of activation. This suggests that parietal cortex is involved not only in discrete shifts of attention between objects at different spatial locations but also in continuous "attentional pursuit" of moving objects. Attentive-tracking activation patterns were also similar, though not identical, to those produced by eye movements. Taken together, these results suggest that attentive tracking is mediated by a network of areas that includes parietal and frontal regions responsible for attention shifts and eye movements and the MT complex, thought to be responsible for motion perception. These results are consistent with theoretical models of attentive tracking as an attentional process that assigns spatial tags to targets and registers changes in their position, generating a high-level percept of apparent motion.