Language structure in the brain: A fixation-related fMRI study of syntactic surprisal in reading

• Published in: NeuroImage (Orlando, Fla.) Vol. 132; pp. 293 - 300
• Main Authors: Henderson, John M., Choi, Wonil, Lowder, Matthew W., Ferreira, Fernanda
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.05.2016; Elsevier Limited
• Subjects: Adolescent; Adult; Brain - physiology; Brain Mapping; Comprehension - physiology; Eye Movement Measurements; Eye movements; Female; Fixation, Ocular; fMRI; Humans; Language; Linguistics; Magnetic Resonance Imaging; Male; Neural networks; Prefrontal Cortex - physiology; Reading; Standard deviation; Surprisal; Syntax; Temporal Lobe - physiology; Young Adult; Surprisal; fMRI; Reading; Eye movements; Language; Syntax
• ISSN: 1053-8119; 1095-9572; 1095-9572
• DOI: 10.1016/j.neuroimage.2016.02.050

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. •Participants read connected text paragraphs naturally with eyetracking and fMRI•Fixation-related (FIRE) fMRI was used to relate syntactic surprisal to activation.•Predicted activation for higher surprisal was observed in left IFG and left ATL.•Activation also seen in bilateral insula; and right IFG, fusiform, and lingual gyri.