Raposo A, Moss H E, Stamatakis E A, Tyler L K
Department of Experimental Psychology, University of Cambridge, Cambridge CB2 3EB, UK.
Neuropsychologia. 2006;44(12):2284-95. doi: 10.1016/j.neuropsychologia.2006.05.017. Epub 2006 Jun 27.
The priming of a stimulus by another has become an important tool for exploring the neural underpinnings of conceptual representations. However, priming effects can derive from many different types of relationships and it is important to distinguish between them in order to be able to develop theoretical accounts of the representation of conceptual knowledge. While it is well known that repetition priming (the repeated presentation of the same stimulus) is associated with a reduced neural response, called repetition suppression (RS), the neural correlates of semantic priming (when two stimuli are related in meaning but not identical) are not so well established. We compared the neural correlates of repetition and semantic priming using written words, independently manipulating form and meaning. In an fMRI study, subjects saw single words and made a concrete-abstract decision. Two consecutive words were identical (town-town) or varied along a continuum of semantic relatedness, from highly related (cord-string) to unrelated (face-sail). We found distinct patterns of activation for repetition and semantic priming. Repetition priming was associated with RS in LIFG, bilateral parahippocampal gyrus and R fusiform gyrus. We also observed increased activation for word repetition in the RMFG and RMTG/STG, which may reflect recognition of item's earlier presentation. There was no evidence of suppression for semantic relatedness. Semantic priming was associated with enhanced activation in multiple bilateral fronto-temporal areas, i.e. semantic enhancement. The results suggest that repetition and semantic priming in visual word recognition depend on distinct cognitive processes and neural substrates.
一个刺激对另一个刺激的启动效应已成为探索概念表征神经基础的重要工具。然而,启动效应可能源于许多不同类型的关系,为了能够发展概念知识表征的理论解释,区分它们很重要。虽然众所周知,重复启动(同一刺激的重复呈现)与一种被称为重复抑制(RS)的神经反应减弱有关,但语义启动(当两个刺激在意义上相关但不相同)的神经关联尚未得到很好的确立。我们使用书面单词比较了重复启动和语义启动的神经关联,独立地操纵形式和意义。在一项功能磁共振成像(fMRI)研究中,受试者看到单个单词并做出具体-抽象判断。两个连续的单词相同(town-town),或者沿着语义相关性的连续统变化,从高度相关(cord-string)到不相关(face-sail)。我们发现了重复启动和语义启动不同的激活模式。重复启动与左额下回(LIFG)、双侧海马旁回和右梭状回中的重复抑制有关。我们还观察到右侧额中回(RMFG)和右侧颞中回/颞上回(RMTG/STG)中单词重复的激活增加,这可能反映了对项目先前呈现的识别。没有证据表明语义相关性存在抑制。语义启动与多个双侧额颞区域的激活增强有关,即语义增强。结果表明,视觉单词识别中的重复启动和语义启动依赖于不同认知过程和神经基质。