Milham Michael P, Banich Marie T, Barad Vikram
The Beckman Institute, University of Illinois at Urbana-Champaign, 405 N. Matthews, Urbana, IL 61801, USA.
Brain Res Cogn Brain Res. 2003 Jul;17(2):212-22. doi: 10.1016/s0926-6410(03)00108-3.
Prior work indicates that various aspects of task-irrelevant information (e.g. its salience, task-relatedness, emotionality) can increase the involvement of prefrontal cortex (PFC) in top-down attentional control. In light of these findings, we hypothesize that PFC's involvement increases when task-irrelevant information competes for priority in processing. In an event-related fMRI study using an oddball variant of the Stroop task, we examine the generality of this hypothesis using three manipulations designed to increase the ability of task-irrelevant information to compete for priority in processing. First, we investigated how the frequency of occurrence of task-irrelevant information affects PFC activity. Second, we examined whether conflicting color information (i.e. incongruent trials) increases activity in regions of PFC that are similar to or distinct from those sensitive to infrequently occurring task-irrelevant information. Finally, we examined the impact of the number of levels at which conflict could occur (e.g. non-response only, non-response and response). Activity in posterior-dorsolateral and posterior-inferior PFC increased for infrequently occurring task-irrelevant information, being largest when the task-irrelevant information contained conflicting color-information. In contrast, increases in mid-dorsolateral prefrontal cortex's activity were only noted when conflicting color information was present, being largest when conflict occurred at multiple levels. The anterior cingulate was primarily sensitive to the occurrence of conflict at the response level with only a small sub-region exhibiting sensitivity to non-response conflict as well. From these findings we suggest that posterior DLPFC and PIPFC are involved in biasing processing in posterior processing systems, mid-DLPFC is involved in biasing the processing of the contents of working memory, and ACC is primarily involved in response-related processes.
先前的研究表明，任务无关信息的各个方面（例如其显著性、与任务的相关性、情感性）会增加前额叶皮层（PFC）在自上而下注意力控制中的参与度。鉴于这些发现，我们假设当任务无关信息在处理过程中争夺优先级时，PFC的参与度会增加。在一项使用Stroop任务的奇偶数变体的事件相关功能磁共振成像研究中，我们通过三种旨在增强任务无关信息在处理过程中争夺优先级能力的操作来检验这一假设的普遍性。首先，我们研究了任务无关信息的出现频率如何影响PFC的活动。其次，我们检查了冲突颜色信息（即不一致试验）是否会增加PFC区域的活动，这些区域与对罕见的任务无关信息敏感的区域相似或不同。最后，我们研究了可能发生冲突的水平数量（例如仅无反应、无反应和反应）的影响。对于罕见的任务无关信息，后外侧和后下PFC的活动增加，当任务无关信息包含冲突颜色信息时最大。相比之下，只有当存在冲突颜色信息时，背外侧前额叶中部皮层的活动才会增加，当冲突在多个水平发生时最大。前扣带回主要对反应水平的冲突发生敏感，只有一小部分区域对无反应冲突也敏感。从这些发现中我们认为，后外侧背侧前额叶皮层和后下前额叶皮层参与偏向于后处理系统中的处理，背外侧前额叶中部皮层参与偏向于工作记忆内容的处理，而前扣带回主要参与与反应相关的过程。
