dissociation-confounding-influences-expectancy-integrative-difficulty

Dissociation of the Confounding Influences of Expectancy and Integrative Difficulty Residing in Anomalous Sentences in Event-related Potential Studies

The confounding factors of unexpectedness and semantic integration difficulty naturally residing in anomalous sentences in language studies make it ...

interaction-between-phonological-semantic-processes-visual-word

Interaction between Phonological and Semantic Processes in Visual Word Recognition using Electrophysiology

Controversies have always existed in research related to reading abilities; on whether printed words are perceived in a feedforward manner based on ...

Tsinghua University

Beijing Normal University

In this study, to explore the plasticity of the alpha/beta-hydrolase fold family, we converted bromoperoxidase A2 (BPO-A2) from Streptomyces aureofaciens to a lipase by structure comparison with lipase A (LipA) from Bacillus subtilis. These two enzymes have similar structures (2.1 A rmsd) and a very low level of sequence identity ( approximately 18%). A variant BL1 was constructed by deleting the caplike domain of BPO-A2 and further fine-tuning the newly formed substrate binding site. The lipase activity was successfully transplanted on BL1, while the halogenation activity was totally lost. BL1 also showed higher hydrolytic activities toward long chain p-nitrophenyl esters, such as p-nitrophenyl caprylate (3.7-fold) and p-nitrophenyl palmitate (7.0-fold), while its activity toward a short chain ester (p-nitrophenyl acetate) decreased dramatically, to only 1.2% of that of BPO-A2. After two rounds of directed evolution and site-directed mutagenesis on selected residues, several mutants with both improved hydrolytic activities and substrate preferences toward long chain substrates were obtained. The highest hydrolytic activity toward p-nitrophenyl palmitate of the best mutant BL1-2-E8-plusI was improved by 40-fold compared with that of BL1. These results demonstrate the possibility of manipulating the caplike domain of alpha/beta-hydrolase fold enzymes and provide further understanding of the structure-function relationship of the alpha/beta-hydrolase fold enzymes. The design strategy used in this study could serve as a useful approach for constructing variants with targeted catalytic properties using the alpha/beta-hydrolase fold.

Morphing activity between structurally similar enzymes: from heme-free bromoperoxidase to lipase.

It remains an open question whether the amplitude of N400 reflects combinatory postlexical semantic integration processing. To examine the issue, we repeatedly presented strictly simplified, N400-eliciting three-word structures for seven times, mixed with their plausible counterparts, followed immediately by a much more enriched and informative sentence containing two keywords of the incongruous structure, for the purpose of reinitiating semantic integration processing. Event-related potentials were recorded and compared at the first, fourth, seventh, and eighth time. It was found that multiple repetitions attenuated the N400 effect to almost nonexistent and that the follow-up semantic integration reinitiating sentence did not recover N400 amplitude. The results suggest that combinatory postlexical semantic integration does not significantly modulate N400 amplitude, and provide evidence for noncombinatory processes underlying N400 such as automatic spreading activation and expectancy/prediction.

N400 amplitude does not recover from disappearance after repetitions despite reinitiated semantic integration difficulty.

The present study aims to delineate the working mechanism of prediction in sentence comprehension, by disentangling the influence of the facilitated general memory retrieval from the coexistent influence of the predicted language-specific semantic and/or syntactic information for the first time. The results support that prediction might influence the downstream cognitive processing in two aspects: (1) the pre-activated information facilitates the retrieval of a matched input in memory and, (2) the pre-activated information interacts with higher-level semantic/syntactic processing. More importantly, the present findings suggest that these two types of influences seem to occur at different stages of sentence comprehension: the facilitated memory retrieval of the input modulates N400 amplitude and the latency of post-N400 late central-parietal positivity/P600, while the predicted semantic/syntactic information and/or their interactions modulate the amplitude of the late positivity. The present findings would be helpful for interpreting the underlying mechanism of observed effects in prediction studies.

Delving Into the Working Mechanism of Prediction in Sentence Comprehension: An ERP Study.

Unlike in English, the role of phonology in word recognition in Chinese is unclear. In this event-related potential experiment, we investigated the role of phonology in reading both high- and low-frequency two-character compound Chinese words. Participants executed semantic and homophone judgment tasks of the same precede-target pairs. Each pair of either high- or low-frequency words were either unrelated (control condition) or related semantically or phonologically (homophones). The induced P200 component was greater for low- than for high-frequency word-pairs both in semantic and phonological tasks. Homophones in the semantic judgment task and semantically-related words in the phonology task both elicited a smaller N400 than the control condition, word frequency-independently. However, for low-frequency words in the phonological judgment task, it was found that the semantically related pairs released a significantly larger P200 than the control condition. Thus, the semantic activation of both high- and low-frequency words may be no later than phonological activation.

ArticleTotal : 2	Year
Publication title Cited by 2	2019
Publication title Cited by 4	2021

Article	Year
Morphing activity between structurally similar enzymes: from heme-free bromoperoxidase to lipase. Biochemistry\| PubMed ID: 19883129	2009
N400 amplitude does not recover from disappearance after repetitions despite reinitiated semantic integration difficulty. Neuroreport\| PubMed ID: 30096130	2018
Delving Into the Working Mechanism of Prediction in Sentence Comprehension: An ERP Study. Frontiers in psychology\| PubMed ID: 33679524	2021
An ERP Study on the Role of Phonological Processing in Reading Two-Character Compound Chinese Words of High and Low Frequency. Frontiers in psychology\| PubMed ID: 33716906	2021

Yunlong Huang

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