SISSA International School for Advanced Studies, via Bonomea 265, 34136 Trieste, Italy.
Neuropsychologia. 2012 Apr;50(5):655-65. doi: 10.1016/j.neuropsychologia.2012.01.002. Epub 2012 Jan 11.
The way the brain binds together words to form sentences may depend on whether and how the arising cognitive representation is to be used in behavior. The amplitude of the N400 effect in event-related brain potentials is inversely correlated with the degree of fit of a word's meaning into a semantic representation of the preceding discourse. This study reports a double dissociation in the latency characteristics of the N400 effect depending on task demands. When participants silently read words in a sentence context, without issuing a relevant overt response, greater temporal alignment over recording sites occurs for N400 onsets than peaks. If however a behavior is produced - here pressing a button in a binary probe selection task - exactly the opposite pattern is observed, with stronger alignment of N400 peaks than onsets. The peak amplitude of the N400 effect correlates best with the latency characteristic showing less temporal dispersion. These findings suggest that meaning construction in the brain is subtly affected by task demands, and that there is complex functional integration between semantic combinatorics and control systems handling behavioral goals.
大脑将单词组合成句子的方式可能取决于出现的认知表征是否以及如何用于行为。事件相关脑电位中的 N400 效应的幅度与单词的含义与前文话语的语义表征的匹配程度成反比。本研究报告了 N400 效应的潜伏期特征取决于任务要求的双重分离。当参与者在句子语境中默读单词而不发出相关的外显反应时，与 N400 起始相比，记录部位之间的时间对准更好。但是，如果产生行为 - 这里是在二进制探针选择任务中按按钮 - 则观察到完全相反的模式，N400 峰的对准比起始更强。N400 效应的峰值幅度与显示较少时间分散的潜伏期特征相关性最好。这些发现表明，大脑中的意义构建受到任务要求的微妙影响，并且语义组合和处理行为目标的控制系统之间存在复杂的功能整合。
