Center for Neuroscience, University of California, Davis.
J Cogn Neurosci. 1997 Jan;9(1):39-66. doi: 10.1162/jocn.1997.9.1.39.
In this study the N400 component of the event-related potential was used to investigate spoken sentence understanding in Broca's and Wernicke's aphasics. The aim of the study was to determine whether spoken sentence comprehension problems in these patients might result from a deficit in the on-line integration of lexical information. Subjects listened to sentences spoken at a normal rate. In half of these sentences, the meaning of the final word of the sentence matched the semantic specifications of the preceding sentence context. In the other half of the sentences, the sentence-final word was anomalous with respect to the preceding sentence context. The N400 was measured to the sentence-final words in both conditions. The results for the aphasic patients (n = 14) were analyzed according to the severity of their comprehension deficit and compared to a group of 12 neurologically unimpaired age-matched controls, as well as a group of 6 nonaphasic patients with a lesion in the right hemisphere. The nonaphasic brain damaged patients and the aphasic patients with a light comprehension deficit (high comprehenders, n = 7) showed an N400 effect that was comparable to that of the neurologically unimpaired subjects. In the aphasic patients with a moderate to severe comprehension deficit (low comprehenders, n = 7), a reduction and delay of the N400 effect was obtained. In addition, the P300 component was measured in a classical oddball paradigm, in which subjects were asked to count infrequent low tones in a random series of high and low tones. No correlation was found between the occurrence of N400 and P300 effects, indicating that changes in the N400 results were related to the patients' language deficit. Overall, the pattern of results was compatible with the idea that aphasic patients with moderate to severe comprehension problems are impaired in the integration of lexical information into a higher order representation of the preceding sentence context.
在这项研究中，我们使用事件相关电位的 N400 成分来研究布罗卡氏失语症和韦尼克氏失语症患者的口语句子理解。本研究的目的是确定这些患者的口语句子理解问题是否可能是由于词汇信息在线整合过程中的缺陷所致。被试者听以正常语速说出的句子。在这些句子的一半中，句子最后一个词的意思与前一句上下文的语义规范相匹配。在另一半句子中，句子最后一个词与前一句上下文是异常的。我们在这两种情况下都测量了句子最后一个词的 N400。对 14 名失语症患者的结果按照他们理解障碍的严重程度进行了分析，并与一组 12 名神经功能正常的年龄匹配的对照组以及一组 6 名右侧大脑半球损伤但无失语症的非失语症患者进行了比较。无失语症的脑损伤患者和理解障碍较轻的失语症患者（高理解者，n=7）的 N400 效应与神经功能正常的对照组相似。在理解障碍程度中等至严重的失语症患者（低理解者，n=7）中，N400 效应减少且延迟。此外，我们在经典的奇偶范式中测量了 P300 成分，在该范式中，被试者被要求在随机的高音和低音序列中计算低频的异常次数。未发现 N400 和 P300 效应之间存在相关性，这表明 N400 结果的变化与患者的语言缺陷有关。总的来说，结果模式与中度至重度理解问题的失语症患者在将词汇信息整合到前一句上下文的更高阶表示中存在缺陷的观点是一致的。
