Université de Provence and Centre National de la Recherche Scientifique, Marseille cedex 3, France.
J Cogn Neurosci. 2011 Nov;23(11):3318-30. doi: 10.1162/jocn_a_00030. Epub 2011 Mar 31.
Attention can be directed not only toward a location in space but also to a moment in time ("temporal orienting"). Temporally informative cues allow subjects to predict when an imminent event will occur, thereby speeding responses to that event. In contrast to spatial orienting, temporal orienting preferentially activates left inferior parietal cortex. Yet, left parietal cortex is also implicated in selective motor attention, suggesting its activation during temporal orienting could merely reflect incidental engagement of preparatory motor processes. Using fMRI, we therefore examined whether temporal orienting would still activate left parietal cortex when the cued target required a difficult perceptual discrimination rather than a speeded motor response. Behaviorally, temporal orienting improved accuracy of target identification as well as speed of target detection, demonstrating the general utility of temporal cues. Crucially, temporal orienting selectively activated left inferior parietal cortex for both motor and perceptual versions of the task. Moreover, conjunction analysis formally revealed a region deep in left intraparietal sulcus (IPS) as common to both tasks, thereby identifying it as a core neural substrate for temporal orienting. Despite the context-independent nature of left IPS activation, complementary psychophysiological interaction analysis revealed how the functional connectivity of left IPS changed as a function of task context. Specifically, left IPS activity covaried with premotor activity during motor temporal orienting but with visual extrastriate activity during perceptual temporal orienting, thereby revealing a cooperative network that comprises both temporal orienting and task-specific processing nodes.
注意力不仅可以指向空间中的某个位置，还可以指向时间上的某个时刻（“时间定向”）。时间信息提示可以让被试预测即将发生的事件何时发生，从而加快对该事件的反应。与空间定向相比，时间定向优先激活左下顶叶皮层。然而，左顶叶皮层也与选择性运动注意力有关，这表明其在时间定向中的激活可能仅仅反映了预备运动过程的偶然参与。因此，我们使用 fMRI 检查了当提示目标需要进行困难的知觉辨别而不是快速的运动反应时，时间定向是否仍然会激活左顶叶皮层。行为上，时间定向提高了目标识别的准确性和目标检测的速度，证明了时间提示的普遍适用性。至关重要的是，时间定向选择性地激活了运动和知觉任务的左下顶叶皮层。此外，联合分析正式揭示了左顶内沟（IPS）深处的一个区域是两个任务共有的，从而将其确定为时间定向的核心神经基质。尽管左 IPS 激活具有上下文独立性，但互补的心理生理交互分析揭示了左 IPS 的功能连接如何随着任务上下文的变化而变化。具体来说，在运动时间定向期间，左 IPS 活动与运动前区活动共变，但在知觉时间定向期间与视觉外纹状体活动共变，从而揭示了一个包含时间定向和任务特定处理节点的协作网络。
