从JNC高血压指南的演变史看盐与高血压的关系

高血压是当今世界上最大的流行病,是脑卒中、心脏病及肾脏病最主要的危险因素。通过回顾比较不同时期的JNC高血压指南,了解对盐与高血压关系认识的发展过程,体会限盐对高血压防治的重要性及发展前景。     

ABCD2评分法预测短暂性脑缺血发作后脑卒中发病风险的研究

为探讨APCD2评分法在短暂性脑缺血发作（T1A）后脑卒中发生风险的预测价值,选择发病48小时内的颈内动脉系统TIA患者112例进行ABCD2评定并分为0分、低危、中危、高危组并随访6个月。结果显示,高危组血管狭窄和软斑块程度较0分组、低危组、中危组显著严重;7天时高危组较中危、低危组卒中发生率显著增高;30天、60天...     

宫颈癌病因及预防

从哲学角度讨论宫颈癌的病因,思考临床工作中如何预防宫颈癌。宫颈癌的发生是内因外因综合作用的结果。实验与临床研究发现人类乳头瘤病毒（HPV）家族中的高危型HPV的持续感染是宫颈癌及其癌前病变发生的主要外因。本文将讨论HPV分型检测作为宫颈癌筛查系统的一个重要元素在预防宫颈癌发生中所处的地位。     

The N400 effect in children: relationships with comprehension, vocabulary and decoding

Using event-related potentials (ERPs), we investigated the N400 (an ERP component that occurs in response to meaningful stimuli) in children aged 8-10 years old and examined relationships between the N400 and individual differences in listening comprehension, word recognition and non-word decoding. Moreover, we tested the claim that the N400 effect provides a valuable indicator of behavioural vocabulary knowledge. Eighteen children were presented with picture-word pairs that were either ‘congruent’ (the picture depicted the spoken word) or ‘incongruent’ (they were unrelated). Three peaks were observed in the ERP waveform triggered to the onset of the picture-word stimuli: an N100 in fronto-central channels, an N200 in central-parietal channels and an N400 in frontal, central and parietal channels. In contrast to the N100 peak, the N200 and N400 peaks were sensitive to semantic incongruency with greater peak amplitudes for incongruent than congruent conditions. The incongruency effects for each peak correlated positively with listening comprehension but when the peak amplitudes were averaged across congruent/incongruent conditions they correlated positively with non-word decoding. These findings provide neurophysiological support for the position that sensitivity to semantic context (reflected in the N400 effect) is crucial for comprehension whereas phonological decoding skill relates to more general processing differences reflected in the ERP waveform. There were no correlations between ERP and behavioural measures of expressive or receptive vocabulary knowledge for the same items, suggesting that the N400 effect may not be a reliable estimate of vocabulary knowledge in children aged 8-10 years.     

Sublexical ambiguity effect in reading Chinese disyllabic compounds

For Chinese compounds, neighbors can share either both orthographic forms and meanings, or orthographic forms only. In this study, central presentation and visual half-field (VF) presentation methods were used in conjunction with ERP measures to investigate how readers solve the sublexical semantic ambiguity of the first constituent character in reading a disyllabic compound. The sublexical ambiguity of the first character was manipulated while the orthographic neighborhood sizes of the first and second character (NS1, NS2) were controlled. Subjective rating of number of meanings corresponding to a character was used as an index of sublexical ambiguity. Results showed that low sublexical ambiguity words elicited a more negative N400 than high sublexical ambiguity words when words were centrally presented. Similar patterns were found when words were presented to the left VF. Interestingly, different patterns were observed for pseudowords. With left VF presentation, high sublexical ambiguity psudowords showed a more negative N400 than low sublexical ambiguity pseudowords. In contrast, with right VF presentation, low sublexical ambiguity pseudowords showed a more negative N400 than high sublexical ambiguity pseudowords. These findings indicate that a level of morphological representation between form and meaning needs to be established and refined in Chinese. In addition, hemispheric asymmetries in the use of word information in ambiguity resolution should be taken into account, even at sublexical level.     

Neural activity reveals effects of aging on inhibitory processes during word retrieval

Word retrieval difficulties are one of the most frustrating problems for older adults. Poorer access to phonological representation of the target word has been postulated as the underlying deficit, supported by findings of improved word retrieval after phonological priming. To better understand aging effects in the underlying neurophysiology associated with word retrieval, this study examined electrophysiological correlates of phonological priming and word retrieval in adults. Young, middle-aged, and older adults viewed pictures that were preceded by pseudo-word primes that either shared initial phonemes with or were unrelated to the picture’s name. Participants made phonological judgments regarding the prime and picture prior to naming the picture. Behavioral and event-related potential correlates of phonological priming and word retrieval were recorded. All groups benefitted similarly from phonological priming, evidenced by faster phonological judgment response times and increased ease of word retrieval for primed pictures, indexed by the N400 priming effect. The peak latency of the N2, however, showed an incremental delay with age. High correlation between N2 peak latency and clinical measures of inhibition suggested an age-related delay in the inhibition of primed lexical competitors. Taken together, our results indicated intact activation of phonological representation of the picture’s name but age-related delays in inhibition of primed competitors. Interestingly, our findings revealed that delays in inhibiting lexical competitors may begin as early as middle age, highlighting the importance of including multiple age groups to better represent the aging trajectory.     

Event-related potential (ERP) evidence for the differential cognitive processing of semantic jokes and pun jokes

Brain-imaging studies report that separate neural correlates are associated with processing of different types of humorous materials. However, such evidence lacks temporal information. In this study, we examined the temporal dynamics of humour comprehension between two types of jokes: semantic (SEMs) and pun (PUNs) jokes, using electroencephalographic (EEG) techniques. Thirty SEMs and 30 PUNs were presented to 16 healthy subjects, and their EEG data were concurrently recorded. PUNs consequently showed a larger N400 amplitude than did SEMs, without a specified scalp site, which implies that PUNs induce greater surprise and semantic violation. Meanwhile, SEMs induced a larger P600-like amplitude at the posterior site, which implies that, in order to understand SEMs, higher working memory loads are needed to form novel associations and successfully frame-shift. A possible explanation is the differing logical mechanisms used to understand SEMs and PUNs: the former builds on semantic relationships, the latter on phonological causality.     

Gapping: Electrophysiological evidence for immediate processing of "missing" verbs in sentence comprehension

In the present study we use event related potentials (ERPs) to explore the time course of identification and resolution of verb gaps. ERPs were recorded while participants read sentences that contained a verb gap like Ron took/sanded the planks, and Bill ? the hammer... Plausibility of the critical words (hammer) that followed the verb gap was manipulated. Relative to the plausible control (preceded by took), ERPs to the critical word in the implausible condition (preceded by sanded) showed an N400, followed by a positivity (P600). ERPs to determiners following gapped verbs showed a negativity between 100 and 300 ms, and a positivity between 300 and 500 ms compared to determiners in non-gapping constructions. These results suggest that the sentence processor recognizes a verb gap and reconstructs the verb information at the earliest possible occasion, and that this reconstruction process is different from the reconstruction of antecedents in other filler-gap constructions (e.g., WH gaps).     

Who Do You Love, Your Mother or Your Horse? An Event-Related Brain Potential Analysis of Tone Processing in Mandarin Chinese

In Mandarin Chinese, word meaning is partially determined by lexical tone (Wang, 1973). Previous studies suggest that lexical tone is processed as linguistic information and not as pure tonal information (Gandour, 1998; Van Lanker & Fromkin, 1973). The current study explored the online processing of lexical tones. Event-related potentials were obtained from 25 Mandarin speakers while they listened to normal and anomalous sentences containing one of three types of semantic anomalies created by manipulating the tone, the syllable, or both tone and syllable (double-anomaly) of sentence-final words. We hypothesized N400 effects elicited by all three types of anomalies and the largest by the double-anomaly. As expected, all three elicited N400 effects starting approximately 150 ms poststimulus and continuing until 1000 ms in some areas. Surprisingly, onset of the double-anomaly effect was approximately 50 ms later than the rest. Delayed detection of errors in this condition may be responsible for the apparent delay. Slight differences between syllable and tone conditions may be due to the relative timing of these acoustic cues.     

Equivalence relations do exist before they are tested: Confirmatory evidence revealed by EEG measurements

We examined equivalence-based N400 effects by comparing EEG data from participants with different experiences with equivalence testing. Before a priming task used in EEG measurement, Group 1 was given only matching-to-sample training trials whereas Group 2 was exposed to matching-to-sample training and equivalence probe trials. We asked whether exposure to the reinforcement contingency was sufficient to bring about an N400 outcome that might indicate potentially emergent equivalence relations or if such a response depended on experience with equivalence tests. Results showed robust N400 in both groups. Experience with equivalence tests did not further increase the N400 effects. Our findings add confirmatory evidence that equivalence relations may originate via the reinforcement contingency alone. Furthermore, complementary EEG data collected from priming tasks involving words from natural language showed functional overlap between laboratory-defined equivalence and natural word-based N400 effects.