This paper investigates how late L2 learners resolve filler-gap dependencies (FGD) in real-time and how proficiency and working memory (WM) modulate their brain responses in an event-related potential (ERP) experiment. A group of intermediate to highly proficient Mandarin Chinese learners of English listened to sentences such as “The zebra that the hippo kissed *the camel on the nose ran far away,” in which the extra noun phrase “the camel” created a ‘filled-gap’ effect. The results show that although L2 behavioral responses are comparable to native speakers and are positively correlated with proficiency and WM span, the brain responses to the filled gap are qualitatively different. Importantly, L2 processing patterns did not become more nativelike with higher proficiency levels or greater WM capacity. Specifically, while the native speakers exhibited a P600 typically observed for syntactic violations and repair, the L2 group produced a prefrontal-central positivity. Similar ERPs have previously been reported to reflect domain-general attentional and non-structural-based processes, suggesting that the L2 group has a reduced sensitivity to structural requirements for gap positing in the online resolution of FGDs. Our findings are discussed in light of various proposals accounting for L1-L2 processing differences, including the Shallow Structure Hypothesis.

Background Chaihu-Guizhi-Ganjiang Decoction (CGGD) is a traditional Chinese medicine (TCM) prescription used to treat viral influenza in China. There is evidence that CGGD can be used to treat irritable bowel syndrome (IBS) but the potential mechanism of action and metabolites produced upon CGGD treatment are not known. Methods Patients with IBS were treated with pinaverium bromide (Dicetel™) and then CGGD after a washout period of 1 week. Both treatments lasted for 30 days. Efficacy and changes in metabolites in plasma after the two treatments were compared. Plasma samples were acquired before and after each treatment, and untargeted metabolics analysis undertaken. Results Efficacy was measured by two systems: the Rome IV criteria and TCM theory. Irrespective of whether the Rome IV criteria or TCM theory were used, CGGD showed significantly better efficacy than Dicetel against IBS. CGGD also had a greater influence on plasma metabolism than Dicetel. Dicetel treatment led to increased tryptophan metabolism (increased levels of 5-Hydroxyindoleacetaldehyde) and increased protein metabolism (increased levels of L-arginine). CGGD use led to increased carnitine metabolism, with increased levels of L-carnitine and acylcarnitine. Such changes in these metabolites could suppress IBS by improving gastrointestinal motility and suppressing pain, depression, and inflammation. Conclusions CGGD appeared to be more efficacious than Dicetel in treating IBS. Metabolomics analysis helped to reveal the biomolecular basis of this beneficial effect.

There is a long-standing debate concerning whether Mandarin topic constructions are movement-derived and form a filler-gap dependency like the English-type topicalization. This ERP study explores this issue by testing whether island constraints, a diagnostic for movement, are actively observed during online processing of the Mandarin “gap-type” topic construction, an understudied area in Mandarin sentence processing research. Following the paradigm of Traxler and Pickering's 1996 study, we manipulated islandhood (relative clause island conditions vs. no island conditions) and plausibility, or whether the topic is a plausible object of the potential subcategorizing verb based on animacy fit (i.e., “greet a teacher” vs. “greet a file”) in a 2 × 2 design. We predict that any plausibility effect obtained for the non-island conditions would disappear for the island conditions if the parser observes the island constraint and avoids positing gaps inside an island. we observed a P600-previously found for animacy violations-for the non-island conditions but not for the island conditions. Additionally, we found a positive-going component occurring from 588 to 792 ms at the fronto-central site for the island condition at the potential gap site. While this novel ERP's interpretation is yet to be determined, it is unlikely to indicate any plausibility effect. Our findings suggest that the parser is sensitive to island constraints in online processing of the Mandarin “gap-type” topic structure, and lend support to the movement analysis for Mandarin topicalization.

The primary function of Mandarin tone is to encode and differentiate otherwise similar-sounding words. In that regard, proficient tone use is essential for both intelligible L2 pronunciation and successful vocabulary learning. Recent research investigating L2 tone use in online Mandarin word recognition revealed persistent difficulties among proficient learners. This paper reviews these findings in light of several tone teaching issues and challenges and proposes a few potential improvements to the current tone word pedagogy. It is suggested that tone instruction can be more effective if it is form-focused, systematically given in conjunction with vocabulary teaching, and backward-designed based on articulated tone word learning objectives and matching assessments. While highlighting the potentials of computer-mediated tone instruction and self-directed learning, the paper also identified a few directions for future research.