Nicotinic cholinergic synaptic mechanisms in the ventral tegmental area contribute to nicotine addiction

Tobacco use is a major health problem that is estimated to cause 4 million deaths a year worldwide. Nicotine is the main addictive component of tobacco. It acts as an agonist to activate and desensitize nicotinic acetylcholine receptors (nAChRs). A component of nicotine's addictive power is attributable to actions on the mesolimbic dopaminergic system, which serves a fundamental role in the acquisition of behaviors that are inappropriately reinforced by addictive drugs. Here we show that nicotine, in the same concentration and time ranges as obtained from tobacco, has three main actions that regulate the activity of midbrain dopamine (DA) neurons. Nicotine first activates and then desensitizes nAChRs on the DA neurons. This process directly excites the DA neurons for a short period of time before the nAChRs desensitize. Nicotine also enhances glutamatergic excitation and decreases GABAergic inhibition onto DA neurons. These events increase the probability for synaptic plasticity, such as long-term potentiation. The short-lived direct excitation of the DA neurons coupled with the enhanced glutamatergic afferent activity provides the presynaptic and postsynaptic coincidence necessary to initiate synaptic potentiation. In total, these synaptic events lead to a relatively long-lasting heightened activity of midbrain DA neurons. Consistent with other summarized studies, this work indicates that the synaptic changes normally associated with learning and memory can be influenced and commandeered during the nicotine addiction process.     

小学生阅读迁移机制的进一步研究--字词表征还是内容表征

探讨阅读文章难易程度与文章字词和内容在小学生篇章阅读迁移中的作用。被试分为阅读水平高、低两组。采用个别方式施测,以阅读时间和阅读准确性为阅读迁移的指标。结果表明,低水平组被试的篇章阅读迁移主要依赖词汇表征;高水平组被试的篇章阅读迁移主要依赖内容表征,换言之,容易文章主要以内容表征进行迁移;困难文章主要以词汇表征进行迁移。     

On local influence analysis of full information item factor models

The full information item factor (FIIF) model is very useful for analyzing relations of dichotomous variables. In this article, we present a feasible procedure to assess local influence of minor perturbations for identifying influence aspects of the FIIF model. The development is based on a Q-displacement function which is closely related with the Monte Carlo EM algorithm in the ML estimation. In the E-step of this algorithm, the conditional expectations are approximated by sample means of observations simulated by the Gibbs sampler from the appropriate conditional distributions. It turns out that these observations can be utilized for computing the building blocks of the proposed diagnostic measures. The diagnoses are based on the conformal normal curvature that can be computed easily. A number of interesting perturbation schemes are considered. The methodology is illustrated with two real examples.The research is fully supported by a grant (CUHK 4356/00H) from the Research Grant Council of the Hong Kong Special Administration Region. The authors are thankful to the Editor, Associate Editor, anonymous reviewers, and W.Y. Poon for valuable comments for improving the paper, and to ICPSR and the relevant founding agency for allowing us to use of their data. The assistance of Michael Leung and Esther Tam is gratefully acknowledged.     

几种时间表征的研究概况

概述时间表征外显与内隐的分类,对动力心理表征及表征动量的研究进行了讨论     

发音人和语境变异与声调知觉

本文用Garner快速分类法研究了发音人规范化和语境补偿过程与声调知觉的关系。得到的主要结果是:(1)发音人变化对声调识别产生了显著的Gar-ner干扰;声调变化对男女声判别产生了同样的十扰。(2)语境变化对声调识别也产生了显著的Garner干扰。按照Garner方法的假设,这说明发音人规范化和语境变异补偿与声调识别之问是相互联系和相互影响的。(3)虽然发音人和语境同时变化引起的声调识别反应时延长约等于它们单独变化时反应时延长量之和,但正确率下降远大于单独变化时下降量之和。说明发音人和语境变异对声调识别的干扰不是独立的,它们之间存在相互作用。这种作用增加了声调识别的难度。     

Social Representations of Human Rights Amongst Czech University Students

The Universal Declaration of Human Rights is a general legislative framework for democratic societies. Studying the social representations of these basic human rights helps to explain how people understand and assess the basic rights and how these rights relate to everyday life. Over 400 Czech university students rated the 30 articles of the Declaration of Human Rights on various scales (degree of understanding, personal relevance, consequences for individual responsibility, for government, political parties, etc.). A semantic space was identified in which concepts (i.e. the Articles of the Declaration) could be located. A typology (clusters) of articles was then established within that semantic space. A factor analysis of the scales resulted in a two-dimensional solution (‘positive attitude’ and ‘personal influence’). Five clusters of assessed articles were identified within this semantic space. (© 1997 by John Wiley & Sons, Ltd.)     

启发式在警觉任务中的交叉复合作用

通过对个体和团队和警觉任务的阶段性研究,本研究发现了启发式对个体警觉任务的交叉复合作用,个体在警觉任务关键信号出现时绩效不一定下降。关键信号出现时成绩的升降取决于关键信号与背景信号的可取性。另外,团队结构克服了个体决策中出现的信息不全和信息加工资源不足的缺陷,使警觉任务在关键事件发生时、发生前和发生后的成绩波动不大。     

父母心理控制与小学生的欺负行为:敌意归因和冷酷无情的作用检验

采用班级整群抽样法选取1847名3~6年级小学生（男生987名;平均年龄10.73±1.16岁）及其家长为被试,采用问卷法考察父母心理控制与小学生欺负行为的关系,同时探讨敌意归因和冷酷无情的中介作用。结果发现：（1）父母心理控制显著正向预测小学生的欺负行为;（2）冷酷无情在父母心理控制与小学生欺负行为间的关系中存在中介作用,敌意归因不发挥中介作用;（3）父母心理控制对小学生欺负行为影响的中介机制不存在显著的性别差异和学段差异。本研究结果表明,冷酷无情是父母心理控制影响小学生欺负行为的重要机制,但敌意归因不是。研究者和实践者应注重对欺负者情感加工能力的关注和干预。     

A Sparse Latent Class Model for Cognitive Diagnosis

Psychometrika - Cognitive diagnostic models (CDMs) are latent variable models developed to infer latent skills, knowledge, or personalities that underlie responses to educational, psychological,...