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Transcranial Photobiomodulation on the Left Inferior Frontal Gyrus Enhances Mandarin Chinese L1 and L2 Complex Sentence Processing Performances
Poster Session D, Saturday, October 26, 10:30 am - 12:00 pm, Great Hall 3 and 4
Luyao Chen1, Mingchuan Yang1, Xiujie Yang1, Dongwei Li1; 1Beijing Normal University
Objective: Owing to the feasibility of shaping the brain, noninvasive brain stimulation (NIBS), which causes electrophysiological or metabolic effects through physical or chemical approaches to alter brain activities, has become a promising method of modulation towards language ability. However, to what extent NIBS could be administered to improve first language (L1) speakers’ and second language (L2) learners’ sentence processing performances is largely unclear yet. Therefore, this study set out to evaluate the causal enhancing effect of a relatively novel NIBS technique, transcranial photobiomodulation (tPBM), recently introduced to modulate various cognitive functions, over the left inferior frontal gyrus (LIFG), a key region for language/syntactic processing, on syntactically complex Mandarin Chinese L1 and L2 sentence processing performances. Methods: Two (L1 and L2) groups of participants (thirty per group) were recruited to receive the double-blind, sham-controlled tPBM intervention via LIFG, followed by the sentence processing, the verbal working memory (WM), and the visual WM tasks (pseudo-randomized across participants). The sentence processing task asked participants to process complex sentences with relative clauses embedded, while the verbal WM task required participants to recall and to judge whether the word and its given position were matched. The contrast between these two tasks may reveal whether sentence processing performance could be improved independently from verbal WM. Moreover, a controlled task, visual WM task, whose performance was reported to be improved after applying tPBM over the right inferior frontal gyrus (RIFG), was adopted to testify whether tPBM effects on LIFG are domain-specific (esp., to language-related processing). Results: Behavioral results revealed a consistent pattern for both groups: (a) tPBM enhanced sentence processing performance but not verbal WM; (b) Participants with lower sentence processing performances under sham tPBM benefited more from active tPBM. (c) As expected, the visual WM performances of both groups were not interfered. Taken together, the current study, for the first time, substantiated that tPBM on LIFG could enhance L1 and L2 sentence processing performances independently without contributing to WM performances, and tPBM-on-LIFG effects might be domain-specific to language abilities. Thus, we propose that tPBM would serve as a promising and cost-effective noninvasive brain stimulation (NIBS) tool for future applications on upregulating the human language faculty.
Topic Areas: Language Development/Acquisition, Syntax and Combinatorial Semantics