Department of Psychology and York Neuroimaging Centre, University of York, York, UK.
Cereb Cortex. 2011 Apr;21(4):831-44. doi: 10.1093/cercor/bhq148. Epub 2010 Aug 23.
Semantic judgments involve both representations of meaning plus executive mechanisms that guide knowledge retrieval in a task-appropriate way. These 2 components of semantic cognition-representation and control-are commonly linked to left temporal and prefrontal cortex, respectively. This simple proposal, however, remains contentious because in most functional neuroimaging studies to date, the number of concepts being activated and the involvement of executive processes during retrieval are confounded. Using functional magnetic resonance imaging, we examined a task in which semantic representation and control demands were dissociable. Words with multiple meanings like "bank" served as targets in a double-prime paradigm, in which multiple meaning activation and maximal executive demands loaded onto different priming conditions. Anterior inferior temporal gyrus (ITG) was sensitive to the number of meanings that were retrieved, suggesting a role for this region in semantic representation, while posterior middle temporal gyrus (pMTG) and inferior frontal cortex showed greater activation in conditions that maximized executive demands. These results support a functional dissociation between left ITG and pMTG, consistent with a revised neural organization in which left prefrontal and posterior temporal areas work together to underpin aspects of semantic control.
语义判断既涉及意义的表示，也涉及指导知识检索的执行机制，以适应任务的要求。语义认知的这两个组成部分——表示和控制——通常分别与左颞叶和前额叶皮层有关。然而，这个简单的提议仍然存在争议，因为在迄今为止的大多数功能神经影像学研究中，被激活的概念数量和检索过程中执行过程的参与是混淆的。我们使用功能磁共振成像研究了一项任务，在该任务中，语义表示和控制的需求是可分离的。具有多个含义的单词（如“bank”）在双重启动范式中用作目标，在这种范式中，多个含义的激活和最大的执行需求加载到不同的启动条件下。前下颞叶回（ITG）对检索到的含义数量很敏感，这表明该区域在语义表示中起作用，而后中部颞叶回（pMTG）和下额叶皮层在最大程度地提高执行需求的条件下表现出更高的激活。这些结果支持左 ITG 和 pMTG 之间的功能分离，与一种新的神经组织一致，即左前额叶和后颞叶区域共同作用，为语义控制的各个方面提供支持。
