Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129, USA.
Cereb Cortex. 2012 Aug;22(8):1887-93. doi: 10.1093/cercor/bhr270. Epub 2011 Sep 21.
The Performance Dip is a newly characterized behavioral phenomenon, where, paradoxically, a weaker task-irrelevant visual stimulus causes larger disturbances on the accuracy of a main letter identification task than a stronger stimulus does. Understanding mechanisms of the Performance Dip may provide insight into unconsciousness behavior. Here, we investigated the generalization of the Performance Dip. Specifically, we tested whether the Performance Dip occurs in a motion-related Simon task, and if so, whether the Performance Dip involves the same brain region, that is, the dorsolateral prefrontal cortex (DLPFC), previously implicated in the Performance Dip, or the supplementary motor area (SMA) and pre-SMA, implicated in a motion-related Simon Task. Subjects made manual directional responses according to the color of stochastic moving dots while ignoring the global direction of moving dots, which could be either congruent or incongruent to the response appropriate to the main task. We found that weak incongruent task-irrelevant stimuli caused a Performance Dip, in which the SMA and pre-SMA, rather than DLPFC, played critical roles. Our results suggest a possible common brain mechanism across different neural circuits, in which weak, but not strong, task-irrelevant information is free from inhibition and intrudes into neural circuits relevant to the main task.
表现下降是一种新的行为现象，矛盾的是，较弱的与任务无关的视觉刺激会比较强的刺激对主要字母识别任务的准确性产生更大的干扰。了解表现下降的机制可能有助于理解无意识行为。在这里，我们研究了表现下降的泛化。具体来说，我们测试了表现下降是否会出现在与运动相关的 Simon 任务中，如果是这样，表现下降是否涉及相同的大脑区域，即先前与表现下降相关的背外侧前额叶皮层（DLPFC），或与运动相关的 Simon 任务相关的补充运动区（SMA）和前 SMA。受试者根据随机移动点的颜色做出手动方向反应，同时忽略移动点的整体方向，该方向可以与主要任务的适当反应一致或不一致。我们发现，较弱的不相干的任务无关刺激会导致表现下降，其中 SMA 和前 SMA 而不是 DLPFC 起着关键作用。我们的结果表明，不同神经回路中可能存在一种共同的大脑机制，其中较弱但不是较强的与任务无关的信息不受抑制的影响，并侵入与主要任务相关的神经回路。
