Fedorenko Evelina, Blank Idan Asher, Siegelman Matthew, Mineroff Zachary
Department of Brain and Cognitive Sciences, MIT, Cambridge, MA 02139, USA; McGovern Institute for Brain Research, MIT, Cambridge, MA 02139, USA.
Department of Brain and Cognitive Sciences, MIT, Cambridge, MA 02139, USA; Department of Psychology, UCLA, Los Angeles, CA 90095, USA.
Cognition. 2020 Oct;203:104348. doi: 10.1016/j.cognition.2020.104348. Epub 2020 Jun 20.
To understand what you are reading now, your mind retrieves the meanings of words and constructions from a linguistic knowledge store (lexico-semantic processing) and identifies the relationships among them to construct a complex meaning (syntactic or combinatorial processing). Do these two sets of processes rely on distinct, specialized mechanisms or, rather, share a common pool of resources? Linguistic theorizing, empirical evidence from language acquisition and processing, and computational modeling have jointly painted a picture whereby lexico-semantic and syntactic processing are deeply inter-connected and perhaps not separable. In contrast, many current proposals of the neural architecture of language continue to endorse a view whereby certain brain regions selectively support syntactic/combinatorial processing, although the locus of such "syntactic hub", and its nature, vary across proposals. Here, we searched for selectivity for syntactic over lexico-semantic processing using a powerful individual-subjects fMRI approach across three sentence comprehension paradigms that have been used in prior work to argue for such selectivity: responses to lexico-semantic vs. morpho-syntactic violations (Experiment 1); recovery from neural suppression across pairs of sentences differing in only lexical items vs. only syntactic structure (Experiment 2); and same/different meaning judgments on such sentence pairs (Experiment 3). Across experiments, both lexico-semantic and syntactic conditions elicited robust responses throughout the left fronto-temporal language network. Critically, however, no regions were more strongly engaged by syntactic than lexico-semantic processing, although some regions showed the opposite pattern. Thus, contra many current proposals of the neural architecture of language, syntactic/combinatorial processing is not separable from lexico-semantic processing at the level of brain regions-or even voxel subsets-within the language network, in line with strong integration between these two processes that has been consistently observed in behavioral and computational language research. The results further suggest that the language network may be generally more strongly concerned with meaning than syntactic form, in line with the primary function of language-to share meanings across minds.
为了理解你现在正在阅读的内容，你的大脑会从语言知识储备中检索单词和结构的含义（词汇语义处理），并识别它们之间的关系以构建复杂的意义（句法或组合处理）。这两组过程是依赖于不同的、专门的机制，还是共享一个共同的资源库呢？语言理论、语言习得与处理的实证证据以及计算建模共同描绘了一幅图景，即词汇语义和句法处理紧密相连，或许无法分开。相比之下，当前许多关于语言神经结构的提议仍然支持这样一种观点，即某些脑区选择性地支持句法/组合处理，尽管这种“句法中枢”的位置及其性质在不同提议中有所不同。在这里，我们使用一种强大的个体受试者功能磁共振成像方法，在先前研究中用于论证这种选择性的三种句子理解范式中，寻找句法处理相对于词汇语义处理的选择性：对词汇语义与形态句法违反的反应（实验1）；在仅词汇项不同与仅句法结构不同的句子对中从神经抑制中恢复（实验2）；以及对这些句子对的相同/不同意义判断（实验3）。在所有实验中，词汇语义和句法条件在整个左额颞语言网络中都引发了强烈的反应。然而，至关重要的是，没有哪个区域在句法处理上比词汇语义处理更活跃，尽管有些区域表现出相反的模式。因此，与当前许多关于语言神经结构的提议相反，在语言网络内的脑区甚至体素子集中，句法/组合处理与词汇语义处理是不可分离的，这与在行为和计算语言研究中一直观察到的这两个过程之间的强整合一致。结果进一步表明，语言网络可能总体上更关注意义而非句法形式，这与语言的主要功能——在不同思维之间共享意义——相符。
