Task-specific repetition priming in left inferior prefrontal cortex.
Task-specific repetition priming in left inferior prefrontal cortex.
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DOI：
10.1093/cercor/10.12.1176
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发表时间：
2000-12
期刊：
影响因子：
3.7
通讯作者：
A. Wagner;W. Koutstaal;Anat Maril;D. Schacter;R. Buckner;R. Buckner
中科院分区：
文献类型：
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作者：
A. Wagner;W. Koutstaal;Anat Maril;D. Schacter;R. Buckner;R. Buckner
先前的神经影像学研究表明，相对于初始（未启动）刺激处理，重复（启动）刺激过程中左下前额皮质（LIPC）的激活减少。前部（大约 BA 45/47）和后部（大约 BA 44/6）LIPC 激活的减少被解释为反映了初始语义或语音处理的内隐记忆。然而，先前的研究并没有明确表明 LIPC 启动效应特定于高级（语义和/或语音）过程的重演，而不是低级（感知）过程。此外，之前没有研究表明前部和后部 LIPC 区域的启动模式是可分离的。为了解决这些问题，目前的功能磁共振成像研究通过检查这些效应的任务特异性来检查 LIPC 启动的性质。参与者最初以语义或非语义方式处理单词。随后，参与者在对之前以语义方式处理过的单词（任务内重复）、之前以非语义方式处理过的单词（跨任务重复）和之前未处理过的单词（新词）做出语义决策时进行扫描。在行为上，观察到特定于任务的启动：在先前的语义处理之后做出语义决策的反应时间下降，但在先前的单词非语义处理之后却没有下降。前 LIPC 的启动与这些结果平行，在任务内重复后观察到信号减少，但在跨任务重复后观察不到信号减少。重要的是，后 LIPC 的神经启动表现出不同的模式：在任务内和跨任务重复后观察到启动，在任务内条件下启动的幅度往往更大。前部和后部 LIPC 区域之间的直接比较揭示了显着的相互作用。这些发现表明，前部和后部 LIPC 表现出不同的启动模式，前部区域的启动是特定于任务的，表明这种促进源自刺激的重复语义处理。
Previous neuroimaging studies have shown that activation in left inferior prefrontal cortices (LIPC) is reduced during repeated (primed) relative to initial (unprimed) stimulus processing. These reductions in anterior (approximately BA 45/47) and posterior (approximately BA 44/6) LIPC activation have been interpreted as reflecting implicit memory for initial semantic or phonological processing. However, prior studies do not unambiguously indicate that LIPC priming effects are specific to the recapitulation of higher-level (semantic and/or phonological), rather than lower-level (perceptual), processes. Moreover, no prior study has shown that the patterns of priming in anterior and posterior LIPC regions are dissociable. To address these issues, the present fMRI study examined the nature of priming in LIPC by examining the task-specificity of these effects. Participants initially processed words in either a semantic or a nonsemantic manner. Subsequently, participants were scanned while they made semantic decisions about words that had been previously processed in a semantic manner (within-task repetition), words that had been previously processed in a nonsemantic manner (across-task repetition), and words that had not been previously processed (novel words). Behaviorally, task-specific priming was observed: reaction times to make the semantic decision declined following prior semantic processing but not following prior nonsemantic processing of a word. Priming in anterior LIPC paralleled these results with signal reductions being observed following within-task, but not following across-task, repetition. Importantly, neural priming in posterior LIPC demonstrated a different pattern: priming was observed following both within-task and across-task repetition, with the magnitude of priming tending to be greater in the within-task condition. Direct comparison between anterior and posterior LIPC regions revealed a significant interaction. These findings indicate that anterior and posterior LIPC demonstrate distinct patterns of priming, with priming in the anterior region being task-specific, suggesting that this facilitation derives from repeated semantic processing of a stimulus.