Sharp David J, Scott Sophie K, Wise Richard J S
MRC-Cyclotron Unit, Clinical Sciences Centre, Imperial College London, London, UK.
Ann Neurol. 2004 Dec;56(6):836-46. doi: 10.1002/ana.20294.
During speech comprehension the auditory association cortex in the superior temporal cortex is involved in perceptual analysis of the speech signal, whereas the basal language area in the inferior temporal cortex mediates access to word meaning. Disruption of the interaction between the superior and inferior temporal cortices is one factor that may determine recovery from aphasic stroke. We used positron emission tomography to investigate semantic processing within inferior temporal cortex in control subjects and after infarction involving the superior temporal cortex. In the control group, semantic decision making on clear speech activated both anterior fusiform gyri. Chronic aphasic patients were impaired at the task and demonstrated reduced activation within the left anterior fusiform gyrus. A similar pattern of impaired performance and reduced left anterior fusiform gyrus activation was observed when control subjects heard perceptually degraded speech. Performance in both groups predicted activity in the right anterior fusiform gyrus and the temporal poles, where accuracy linearly correlated with activity. These results demonstrate that the function of the basal language area is sensitive to changes in the quality of perceptual input. In addition, different profiles of response observed in each hemisphere suggest distinct contributions of both left and right inferior temporal cortices to the semantic processing of speech.
在言语理解过程中，颞上叶皮质中的听觉联合皮质参与言语信号的感知分析，而颞下叶皮质中的基础语言区则介导对词义的获取。颞上叶皮质和颞下叶皮质之间相互作用的中断是可能决定失语性中风恢复情况的一个因素。我们使用正电子发射断层扫描技术，研究了对照组以及颞上叶皮质梗死患者颞下叶皮质内的语义加工情况。在对照组中，对清晰言语进行语义判断时，双侧梭状回前部均被激活。慢性失语症患者在该任务中表现受损，且左侧梭状回前部的激活减弱。当对照组受试者听到感知质量下降的言语时，也观察到了类似的表现受损和左侧梭状回前部激活减弱的模式。两组的表现均预测了右侧梭状回前部和颞极的活动，其中准确性与活动呈线性相关。这些结果表明，基础语言区的功能对感知输入质量的变化很敏感。此外，在每个半球观察到的不同反应模式表明，左右颞下叶皮质对言语语义加工的贡献不同。
