Stelzel Christine, Brandt Stephan A, Schubert Torsten
Department of Psychology, FIMLAB, University of Heidelberg, Germany.
Neuroimage. 2009 Oct 15;48(1):237-48. doi: 10.1016/j.neuroimage.2009.06.064. Epub 2009 Jul 2.
Little is known about how the human brain processes multiple relevant information streams competing for behavior. The present study aimed at specifying the interaction of the lateral prefrontal cortex (lPFC) with task-relevant sensory brain regions during concurrent stimulus processing of two relevant stimuli (S1, S2) in a classical dual-task situation. In detail, we tested whether S1 processing is independent of the task relevance of S2 as has been hypothesised in cognitive theories on dual-task processing. Using functional Magnetic Resonance Imaging, we tested two neural mechanisms that might reflect effects of S2 relevance on S1 processing at different temporal overlaps. The results indicate that: (1) activity amplitudes in S1-relevant regions in the inferior temporal cortex were similarly affected by the temporal overlap between the two stimuli when S2 was relevant or irrelevant and (2) only when S2 was relevant in the dual task, significant increases in the functional coupling between S1-relevant regions and dual-task-related regions in the posterior lPFC were present at high temporal overlap. No similar effects were found for S2-relevant regions. These findings suggest that concurrent stimulus processing in dual tasks is realised by transient changes in functional coupling for stimuli with relatively higher priority (S1).
关于人类大脑如何处理争夺行为控制权的多个相关信息流，我们所知甚少。本研究旨在明确在经典双任务情境中，当同时处理两个相关刺激（S1、S2）时，外侧前额叶皮层（lPFC）与任务相关的感觉脑区之间的相互作用。具体而言，我们检验了S1的处理是否如双任务处理的认知理论所假设的那样，独立于S2的任务相关性。利用功能磁共振成像，我们测试了两种神经机制，它们可能在不同的时间重叠情况下反映S2相关性对S1处理的影响。结果表明：（1）当S2相关或不相关时，颞下叶皮层中与S1相关区域的活动幅度受两种刺激之间时间重叠的影响相似；（2）仅当S2在双任务中相关时，在高时间重叠时，与S1相关区域和lPFC后部双任务相关区域之间的功能耦合才会显著增加。在与S2相关的区域未发现类似效应。这些发现表明双任务中的同时刺激处理是通过对优先级相对较高的刺激（S1）的功能耦合的瞬时变化来实现的。
