Henderson John M, Choi Wonil, Lowder Matthew W, Ferreira Fernanda
University of California, Davis, USA.
University of California, Davis, USA.
Neuroimage. 2016 May 15;132:293-300. doi: 10.1016/j.neuroimage.2016.02.050. Epub 2016 Feb 22.
How is syntactic analysis implemented by the human brain during language comprehension? The current study combined methods from computational linguistics, eyetracking, and fMRI to address this question. Subjects read passages of text presented as paragraphs while their eye movements were recorded in an MRI scanner. We parsed the text using a probabilistic context-free grammar to isolate syntactic difficulty. Syntactic difficulty was quantified as syntactic surprisal, which is related to the expectedness of a given word's syntactic category given its preceding context. We compared words with high and low syntactic surprisal values that were equated for length, frequency, and lexical surprisal, and used fixation-related (FIRE) fMRI to measure neural activity associated with syntactic surprisal for each fixated word. We observed greater neural activity for high than low syntactic surprisal in two predicted cortical regions previously identified with syntax: left inferior frontal gyrus (IFG) and less robustly, left anterior superior temporal lobe (ATL). These results support the hypothesis that left IFG and ATL play a central role in syntactic analysis during language comprehension. More generally, the results suggest a broader cortical network associated with syntactic prediction that includes increased activity in bilateral IFG and insula, as well as fusiform and right lingual gyri.
在语言理解过程中，人类大脑是如何进行句法分析的？当前的研究结合了计算语言学、眼动追踪和功能磁共振成像等方法来解决这个问题。受试者在磁共振成像扫描仪中阅读以段落形式呈现的文本段落，同时记录他们的眼动。我们使用概率上下文无关语法对文本进行解析，以分离句法难度。句法难度被量化为句法意外度，它与给定单词在其前文语境下句法类别的预期性相关。我们比较了长度、频率和词汇意外度相等的高句法意外度值和低句法意外度值的单词，并使用与注视相关的功能磁共振成像（FIRE fMRI）来测量与每个注视单词的句法意外度相关的神经活动。我们在先前已确定与句法相关的两个预测皮质区域中观察到，高句法意外度比低句法意外度引发更强的神经活动：左侧额下回（IFG），以及强度稍弱的左侧颞上回前部（ATL）。这些结果支持了这样一种假设，即左侧额下回和颞上回前部在语言理解过程中的句法分析中起核心作用。更普遍地说，这些结果表明存在一个与句法预测相关的更广泛的皮质网络，包括双侧额下回和脑岛以及梭状回和右侧舌回的活动增加。
