The Congruency Effect in the Posterior Medial Frontal Cortex Is More Consistent with Time on Task than with Response Conflict
The Congruency Effect in the Posterior Medial Frontal Cortex Is More Consistent with Time on Task than with Response Conflict
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DOI：
10.1371/journal.pone.0062405
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发表时间：
2013-04-29
期刊：
影响因子：
3.7
通讯作者：
Carp, Joshua
中科院分区：
文献类型：
--
作者：
Weissman, Daniel H.;Carp, Joshua
后内侧额叶皮层（pMFC）被认为在分心期间控制注意力方面起着关键作用。根据这一观点，pMFC活性在反应干扰的不一致试验中普遍更大（例如，Stroop）任务中的相似性。尽管如此，这种一致性效应背后的过程仍然存在很大争议。因此，我们试图区分一致性效应的两种相互竞争的解释。冲突监测帐户假定的效果索引的过程中，检测竞争的反应方案之间的冲突，这是索引的试验特定的反应时间（RT）。任务时间账户假定效应索引的过程，其招聘随着任务时间的增加而增加，与响应冲突无关（例如，持续的注意力、唤醒、努力等）。为了区分这两种解释，我们使用功能性MRI记录了24名健康成年人在执行两项任务时的大脑活动：反应-干扰任务和只有一种可能反应的简单RT任务。我们推断，在反应干扰任务中，对检测反应冲突的过程的要求应该随着RT的增加而增加，但在简单的RT任务中则不然。与此相反，要求的过程中，其招聘增加与时间无关的反应冲突的任务应增加RT在这两个任务。试验的试验分析表明，pMFC活动增加RT在这两个任务。此外，pMFC活动增加与RT在简单RT任务足以充分说明在反应干扰任务的一致性效应。这些发现似乎更一致的时间上的任务帐户的一致性效应比冲突监测帐户。
The posterior medial frontal cortex (pMFC) is thought to play a pivotal role in enabling the control of attention during periods of distraction. In line with this view, pMFC activity is ubiquitously greater in incongruent trials of response-interference (e.g., Stroop) tasks than in congruent trials. Nonetheless, the process underlying this congruency effect remains highly controversial. We therefore sought to distinguish between two competing accounts of the congruency effect. The conflict monitoring account posits the effect indexes a process that detects conflict between competing response alternatives, which is indexed by trial-specific reaction time (RT). The time on task account posits the effect indexes a process whose recruitment increases with time on task independent of response conflict (e.g., sustained attention, arousal, effort, etc.). To distinguish between these accounts, we used functional MRI to record brain activity in twenty-four healthy adults while they performed two tasks: a response-interference task and a simple RT task with only one possible response. We reasoned that demands on a process that detects response conflict should increase with RT in the response-interference task but not in the simple RT task. In contrast, demands on a process whose recruitment increases with time on task independent of response conflict should increase with RT in both tasks. Trial-by-trial analyses revealed that pMFC activity increased with RT in both tasks. Moreover, pMFC activity increased with RT in the simple RT task enough to fully account for the congruency effect in the response-interference task. These findings appear more consistent with the time on task account of the congruency effect than with the conflict monitoring account.