Devlin Joseph T, Matthews Paul M, Rushworth Matthew F S
FMRIB Center, Department of Clinical Neurology, University of Oxford, John Radcliffe Hospital, Headington, UK.
J Cogn Neurosci. 2003 Jan 1;15(1):71-84. doi: 10.1162/089892903321107837.
The involvement of the left inferior prefrontal cortex (LIPC) in phonological processing is well established from both lesion-deficit studies with neurological patients and functional neuroimaging studies of normals. Its involvement in semantic processing, on the other hand, is less clear. Although many imaging studies have demonstrated LIPC activation during semantic tasks, this may be due to implicit phonological processing. This article presents two experiments investigating semantic functions in the LIPC. Results from a functional magnetic resonance imaging experiment demonstrated that both semantic and phonological processing activated a common set of areas within this region. In addition, there was a reliable increase in activation for semantic relative to phonological decisions in the anterior LIPC while the opposite comparison (phonological vs. semantic decisions) revealed an area of enhanced activation within the posterior LIPC. A second experiment used transcranial magnetic stimulation (TMS) to temporarily interfere with neural information processing in the anterior portion of the LIPC to determine whether this region was essential for normal semantic performance. Both repetitive and single pulse TMS significantly slowed subjects' reactions for the semantic but not for the perceptual control task. Our results clarify the functional anatomy of the LIPC by demonstrating that anterior and posterior regions contribute to both semantic and phonological processing, albeit to different extents. In addition, the findings go beyond simply establishing a correlation between semantic processing and activation in the LIPC and demonstrate that a transient disruption of processing selectively interfered with semantic processing.
左前额叶下回（LIPC）参与语音处理这一点，已在针对神经疾病患者的损伤缺陷研究以及针对正常人的功能性神经影像学研究中得到充分证实。另一方面，它在语义处理中的作用尚不清楚。尽管许多影像学研究表明在语义任务期间LIPC会被激活，但这可能是由于隐性语音处理所致。本文介绍了两项研究LIPC语义功能的实验。一项功能磁共振成像实验的结果表明，语义处理和语音处理均激活了该区域内的一组共同区域。此外，在前部LIPC中，相对于语音决策，语义决策的激活有可靠的增加，而相反的比较（语音决策与语义决策）则显示后部LIPC内有一个激活增强的区域。第二项实验使用经颅磁刺激（TMS）来暂时干扰LIPC前部的神经信息处理，以确定该区域对于正常语义表现是否必不可少。重复性和单脉冲TMS均显著减慢了受试者在语义任务中的反应，但在知觉控制任务中则不然。我们的结果通过证明前部和后部区域均对语义处理和语音处理有贡献，尽管程度不同，从而阐明了LIPC的功能解剖结构。此外，这些发现不仅仅是简单地建立了语义处理与LIPC激活之间的相关性，还证明了处理过程的短暂中断会选择性地干扰语义处理。
