Ruff Ilana, Blumstein Sheila E, Myers Emily B, Hutchison Emmette
Department of Cognitive and Linguistic Sciences, Brown University, 190 Thayer Street, Box 1978, Providence, RI 02912, USA.
Brain Lang. 2008 Apr;105(1):41-9. doi: 10.1016/j.bandl.2008.01.003. Epub 2008 Feb 14.
Previous studies examining explicit semantic processing have consistently shown activation of the left inferior frontal gyrus (IFG). In contrast, implicit semantic processing tasks have shown activation in posterior areas including the superior temporal gyrus (STG) and the middle temporal gyrus (MTG) with less consistent activation in the IFG. These results raise the question whether the functional role of the IFG is related to those processes needed to make a semantic decision or to processes involved in the extraction and analysis of meaning. This study examined neural activation patterns during a semantic judgment task requiring overt semantic analysis, and then compared these activation patterns to previously obtained results using the same semantically related and unrelated word pairs in a lexical decision task which required only implicit semantic processing (Rissman, J., Eliassen, J. C., & Blumstein, S. E. (2003). An event-related fMRI investigation of implicit semantic priming. Journal of Cognitive Neuroscience, 15, 1160-1175). The behavioral results demonstrated that the tasks were equivalent in difficulty. fMRI results indicated that the IFG and STG bilaterally showed greater activation for semantically unrelated than related word pairs across the two tasks. Comparison of the two task types across conditions revealed greater activation for the semantic judgment task only in the STG bilaterally and not in the IFG. These results suggest that the pre-frontal cortex is recruited similarly in the service of both the lexical decision and semantic judgment tasks. The increased activation in the STG in the semantic judgment task reflects the greater depth of semantic processing required in this task and indicates that the STG is not simply a passive store of lexical-semantic information but is involved in the active retrieval of this information.
先前研究明确语义加工时，一直显示左下额回（IFG）激活。相比之下，内隐语义加工任务显示，包括颞上回（STG）和颞中回（MTG）在内的后部区域有激活，而IFG激活不太一致。这些结果引发了一个问题，即IFG的功能作用是与做出语义决策所需的过程有关，还是与意义提取和分析所涉及的过程有关。本研究考察了在需要公开语义分析的语义判断任务期间的神经激活模式，然后将这些激活模式与先前在词汇判断任务中使用相同语义相关和不相关词对所获得的结果进行比较，该词汇判断任务仅需要内隐语义加工（里斯曼，J.，埃利亚森，J.C.，&布卢姆斯坦，S.E.（2003年）。内隐语义启动的事件相关功能磁共振成像研究。《认知神经科学杂志》，15，1160 - 1175）。行为结果表明，这两项任务难度相当。功能磁共振成像结果表明，在这两项任务中，双侧IFG和STG对语义不相关词对比相关词对显示出更大激活。跨条件比较两种任务类型发现，仅在双侧STG而非IFG中，语义判断任务激活更强。这些结果表明，前额叶皮层在词汇判断和语义判断任务中发挥作用的方式相似。语义判断任务中STG激活增加反映了该任务所需语义加工深度更大，表明STG并非仅仅是词汇 - 语义信息的被动存储库，而是参与了该信息的主动检索。
