Poster Session E, Monday, March 25, 2:30 – 4:30 pm, Pacific Concourse
Left inferior frontal gyrus less active for greater syntactic complexity: Magnetoencephalography evidence from minimal Arabic phrases and sentences
Suhail Matar1,2, Julien Dirani2, Alec Marantz1,2, Liina Pylkkänen1,2; 1New York University, 2New York University Abu Dhabi Research Institute
A growing body of literature has generated several disparate hypotheses regarding a fundamental question in language processing: Which brain regions are responsible for syntactic processing? Hypotheses include: a) Syntax is not processed independently in the brain; b) Syntactic processing is distributed across several left-hemispheric regions, and c) The left inferior frontal gyrus (LIFG) –specifically, the pars opercularis– is the locus of syntactic structure building. In this magnetoencephalography (MEG) study, we attempt to tackle this disparity by using an adjectival modification paradigm in Standard Arabic. Fifteen participants read grammatical noun-adjective phrases (‘truck red’/’the-truck the-red’, meaning ‘a/the red truck’), or sentences (‘the-truck red’, meaning ‘The truck is red.’). Though lexical content is identical, and though they are visually minimally different, sentences are more syntactically complex than phrases, since they include tense information. We find an increase in MEG-measured activity in the left anterior temporal lobe (LATL) for both phrases and sentences, compared to single adjectives – in line with previous studies implicating the LATL in basic composition. Contrary to hypothesis (c), activity in the pars opercularis is lower for the syntactically complex sentences compared to phrases, 270-320ms after adjective onset. Our results provide evidence against all the hypotheses above. They indicate separate semantic and syntactic processing of our stimuli. Additionally, rather than syntactic structure building, the LIFG’s role appears to be different, perhaps reflecting structure projection as has been recently proposed (Matchin et al., 2018): unlike our sentences, the simple phrases could be driving the anticipation and projection of upcoming syntactic structure.
Topic Area: LANGUAGE: Syntax