Meta AI, Paris, France; Cognitive Neuroimaging Unit, NeuroSpin Center, 91191 Gif-sur-Yvette, France.
Meta AI, Paris, France; École Normale Supérieure, PSL University, Paris, France.
Cell Rep. 2024 Mar 26;43(3):113847. doi: 10.1016/j.celrep.2024.113847. Epub 2024 Feb 26.
The ability to compose successive words into a meaningful phrase is a characteristic feature of human cognition, yet its neural mechanisms remain incompletely understood. Here, we analyze the cortical mechanisms of semantic composition using magnetoencephalography (MEG) while participants read one-word, two-word, and five-word noun phrases and compared them with a subsequent image. Decoding of MEG signals revealed three processing stages. During phrase comprehension, the representation of individual words was sustained for a variable duration depending on phrasal context. During the delay period, the word code was replaced by a working-memory code whose activation increased with semantic complexity. Finally, the speed and accuracy of retrieval depended on semantic complexity and was faster for surface than for deep semantic properties. In conclusion, we propose that the brain initially encodes phrases using factorized dimensions for successive words but later compresses them in working memory and requires a period of decompression to access them.
将连续的单词组合成有意义的短语的能力是人类认知的一个特征，但它的神经机制仍不完全清楚。在这里，我们使用脑磁图（MEG）分析了语义组合的皮质机制，同时参与者阅读了一个词、两个词和五个词的名词短语，并将其与随后的图像进行了比较。MEG 信号的解码显示了三个处理阶段。在短语理解过程中，单个单词的表示根据短语上下文持续可变的时间。在延迟期间，单词代码被工作记忆代码取代，其激活随语义复杂性增加而增加。最后，检索的速度和准确性取决于语义的复杂性，并且对于表面语义属性来说比对于深度语义属性更快。总之，我们提出大脑最初使用连续单词的分解维度来编码短语，但后来在工作记忆中压缩它们，并需要一个解压期来访问它们。
