University Hospital and University of Geneva, Geneva, Switzerland.
J Cogn Neurosci. 2011 Feb;23(2):374-81. doi: 10.1162/jocn.2010.21412. Epub 2010 Jan 4.
Changes in brain activity characterizing impaired speech production after brain damage have usually been investigated by comparing aphasic speakers with healthy subjects because prestroke data are normally not available. However, when interpreting the results of studies of stroke patients versus healthy controls, there is an inherent difficulty in disentangling the contribution of neuropathology from other sources of between-subject variability. In the present work, we had an unusual opportunity to study an aphasic patient with severe anomia who had incidentally performed a picture naming task in an ERP study as a control subject one year before suffering a left hemisphere stroke. The fortuitous recording of this patient's brain activity before his stroke allows direct comparison of his pre- and poststroke brain activity in the same language production task. The subject did not differ from other healthy subjects before his stroke, but presented major electrophysiological differences after stroke, both in comparison to himself before stroke and to the control group. ERP changes consistently appeared after stroke in a specific time window starting about 250 msec after picture onset, characterized by a single divergent but stable topographic configuration of the scalp electric field associated with a cortical generator abnormally limited to left temporal posterior perilesional areas. The patient's pattern of anomia revealed a severe lexical-phonological impairment and his ERP responses diverged from those of healthy controls in the time window that has previously been associated with lexical-phonological processes during picture naming. Given that his prestroke ERPs were indistinguishable from those of healthy controls, it seems highly likely that the change in his poststroke ERPs is due to changes in language production processes as a consequence of stroke. The patient's neurolinguistic deficits, combined with the ERPs results, provide unique evidence for the role of left temporal cortex in lexical-phonological processing from about 250 to 450 msec during word production.
脑损伤后言语生成障碍的脑活动变化通常通过比较失语症患者和健康受试者来研究，因为通常无法获得发病前的数据。然而，在解释中风患者与健康对照组的研究结果时，从其他来源分离神经病理学的贡献存在内在困难。在本工作中，我们有一个不寻常的机会研究一名严重命名障碍的失语症患者，他在遭受左半球中风前一年作为对照受试者偶然在 ERP 研究中进行了图片命名任务。这名患者在中风前的脑活动的偶然记录使得可以直接比较他在相同语言产生任务中的中风前后的脑活动。该患者在中风前与其他健康受试者没有差异，但在中风后表现出主要的电生理差异，与中风前的自己和对照组相比均如此。ERP 变化在图片呈现后约 250 毫秒的特定时间窗口中持续出现，其特征为头皮电场的单一发散但稳定的拓扑构型，与异常局限于左侧颞后病灶周围区域的皮质发生器相关。患者的命名障碍模式表现为严重的词汇-语音障碍，并且他的 ERP 反应与健康对照组在先前与图片命名过程中的词汇-语音过程相关的时间窗口中不同。鉴于他的中风前 ERP 与健康对照组无法区分，因此很可能他的中风后 ERP 的变化是由于中风导致语言产生过程的变化。患者的神经语言学缺陷，加上 ERP 结果，为左侧颞皮质在词汇-语音处理中的作用提供了独特的证据，大约在 250 到 450 毫秒期间在单词产生期间。
