Institute of Neurology, London.
J Cogn Neurosci. 1997 Nov;9(6):727-33. doi: 10.1162/jocn.1997.9.6.727.
A number of previous functional neuroimaging studies have linked activation of the left inferior frontal gyms with semantic processing, yet damage to the frontal lobes does not critically impair semantic knowledge. This study distinguishes between semantic knowledge and the strategic processes required to make verbal decisions. Using positron emission tomography (PET), we identify the neural correlates of semantic knowledge by contrasting semantic decision on visually presented words to phonological decision on the same words. Both tasks involve identical stimuli and a verbal decision on central lingual codes (semantics and phonology), but the explicit task demands directed attention either to meaning or to the segmentation of phonology. Relative to the phonological task, the semantic task was associated with activations in left extrasylvian temporal cortex with the highest activity in the left temporal pole and a posterior region of the left middle temporal cortex (BA 39) close to the angular gyrus. The reverse contrast showed increased activity in both supramarginal gyri, the left precentral sulcus, and the cuneus with a trend toward enhanced activation in the inferior frontal cortex. These results fit well with neuropsychological evidence, associating semantic knowledge with the extrasylvian left temporal cortex and the segmentation of phonology with the perisylvian cortex.
先前的一些功能神经影像学研究将左额下回的激活与语义处理联系起来，但额叶的损伤并不会严重损害语义知识。本研究区分了语义知识和进行口头决策所需的策略过程。使用正电子发射断层扫描（PET），我们通过对比视觉呈现的单词的语义决策和相同单词的语音决策来确定语义知识的神经相关性。这两个任务都涉及相同的刺激和对中央舌码（语义和语音）的口头决策，但明确的任务要求将注意力集中在意义上或语音的分割上。与语音任务相比，语义任务与左侧额外侧颞叶皮层的激活有关，左颞极和左中颞叶后部（BA39）的一个区域活动最高，该区域靠近角回。相反的对比显示，双侧缘上回、左侧中央前回和楔叶的活动增加，额下回的活动也有增强的趋势。这些结果与神经心理学证据非常吻合，将语义知识与额外侧的左颞叶联系起来，将语音的分割与侧脑室周围皮质联系起来。
