NMDA受体的结构与药理学特性

NMDA受体是一类离子型谷氨酸受体,其功能主要参与发育过程中神经回路的细化及触发多种形式的突触可塑性。近年来的证据表明,组成NMDA受体的亚单位有着复杂的生理学和药理学特性;NMDA受体的数量、分布和亚单位组成并非一成不变,而是在发育过程中、神经元活动时,以一种细胞特异性和突触特异性的方式变化着。这种NMDA受体的双向变化是突触可塑性重塑的基础,而其调节的异常又可导致神经-精神疾病的发生,如可卡因成瘾、精神分裂症等     

语言和文化塑造大脑

不同语言的神经生理基础不同,文化和语言对脑组织的可塑性发挥着重要作用。对儿童、双语者和阅读障碍者语言加工的神经生理机制研究揭示,在不同语言和文化背景下,个体负责语言加工的脑区的结构和功能不同。语言和文化塑造个体的脑组织。     

Post‐traumatic functional recovery and reorganization in animal models: A theoretical and methodological challenge

Studies addressing cerebral functional localization face methodological and theoretical problems. Lesion experiments expect that when a functionally specialized structure is missing, its function can be deduced from the resulting impairments. Mostly, however, initial impairments are partially or fully eliminated through functional recovery. Apparently, such a recovery contradicts the notion of functional localization. In order to understand the mechanisms of recovery, improved methodology and a new theoretical framework are required. Insights into the mechanisms of recovery can be achieved by using “challenge” techniques, where functionally recovered individuals are exposed to organic and behavioral challenges, e.g. pharmacological manipulations or additional lesions, as well as modified test situations. Using such methods, a number of principles of functional recovery have emerged. We evaluate some of the available theories of post‐traumatic recovery against these principles and find that none of them can account for the principles. Finally, we present a new conceptual framework – the Reorganization of Elementary Functions (REF) model. This model reconceptualizes the term “function”, suggests mechanisms of post‐traumatic reorganizations, and resolves the contradiction between localization and functional recovery.     

Role of speechreading in audiovisual interactions during the recovery of speech comprehension in deaf adults with cochlear implants

Speechreading is an important form of communicative activity that improves social adaptation in deaf adults. Cochlear implantation allows interaction between the visual speechreading abilities developed during deafness and the auditory sensory experiences acquired through use of the cochlear implant. Crude auditory information provided by the implant is analyzed in parallel with conjectural information from speechreading, thus creating new profiles of audiovisual integration with implications for brain plasticity. Understanding the peculiarities of change in speechreading after cochlear implantation may improve our understanding of brain plasticity and provide useful information for functional rehabilitation of implanted patients. In this article, we present a generalized review of our recent studies and indicate perspectives for further research in this domain.     

视觉空间关系识别中的认知加工特性

通过两个实验分别检测 2 0名飞行员和 10名老年被试及其相应控制组的视觉空间关系识别中的认知加工水平 ,旨在探讨视觉空间关系识别中的类别关系和数量关系加工子系统所表现出的认知特性。研究结果表明 ,在参与视觉空间关系判断的两个典型加工子系统中 ,负责数量 (坐标 )空间关系判断的加工子系统既可随系统训练而表现出功能增强的练习效应 ,也可随年老过程而发生功能衰减的年龄效应。相对而言 ,涉及类别空间关系判断的加工子系统则较少受到练习和年老化因素的影响。研究提示 ,由于受大脑神经解剖结构特点以及加工任务性质的影响 ,数量空间关系加工子系统更多地表现出了认知加工的可塑性和易变性特点 ,而类别空间关系加工子系统则表现出相对的稳定性或可塑性较低的认知特性     

Seeing how it’s done: matching conditions for observer rats (Rattus norvegicus) in the bidirectional control

In an attempt to increase the reliability of the demonstrator-consistent responding effect produced in the bidirectional control procedure, experiments 1–4 sought conditions that would magnify the matching effect. The aim was to produce a robust demonstrator-consistent responding effect in order that future analytic experiments could investigate the psychological processes responsible for this effect. The joystick responses of observer rats trained using the standard bidirectional control procedure parameters were compared with those of observers subject to conditions identified in the social learning literature as favourable for imitation. Unlike mice, observer rats in experiments 1 a and 1 b tended to push a joystick in the same direction as their demonstrators when the demonstrators were either familiar or unfamiliar males and females. Comparable demonstrator-consistent responding occurred following observation of a standard and a salient joystick response (experiment 2). Experiment 3 showed that the discriminative accuracy of a demonstrator’s responding was important for matching behaviour, and suggested that matching might be enhanced with more than the conventional single observation session. Experiment 4 confirmed that the bidirectional control effect is sensitive to the amount of observational experience; after six observation sessions, demonstrator-inconsistent responding occurs. The results of experiments 1–3 are, and those of experiment 4 are not, compatible with the hypothesis that demonstrator-consistent responding in the bidirectional control is caused by olfactory cues deposited by demonstrators on the joystick. Received: 29 May 2000 / Accepted after revision: 28 August 2000     

干扰控制的训练:内容、效果与机制

研究发现,干扰控制能力具有一定的可塑性。研究者通常选取儿童、成年人、老年人和部分特殊群体为研究对象。研究以Stroop、Flanker等任务为训练任务,训练时间从5天至5周不等,任务量从76至2200试次不等。研究者一般通过行为、脑电和脑成像等技术对训练效果进行评估。训练的研究结果发现,训练后个体的干扰控制能力得到提升,且训练效果可以迁移到其他相关任务中去。干扰控制的训练效果可能受训练任务与评估任务的设置和个体差异等因素的影响。经过认知训练,对冲突信号起监控作用的前扣带回皮层激活程度降低,而执行冲突解决的前额皮层激活程度增强,加强了自上而下的认知控制能力,进而导致干扰控制能力的提升。干扰控制训练的保持效果、机制探讨等问题将成为该领域日后重点关注的内容。     

Late‐ but not early‐onset blindness impairs the development of audio‐haptic multisensory integration

Integrating different senses to reduce sensory uncertainty and increase perceptual precision can have an important compensatory function for individuals with visual impairment and blindness. However, how visual impairment and blindness impact the development of optimal multisensory integration in the remaining senses is currently unknown. Here we first examined how audio‐haptic integration develops and changes across the life span in 92 sighted (blindfolded) individuals between 7 and 70 years of age. We used a child‐friendly task in which participants had to discriminate different object sizes by touching them and/or listening to them. We assessed whether audio‐haptic performance resulted in a reduction of perceptual uncertainty compared to auditory‐only and haptic‐only performance as predicted by maximum‐likelihood estimation model. We then compared how this ability develops in 28 children and adults with different levels of visual experience, focussing on low‐vision individuals and blind individuals that lost their sight at different ages during development. Our results show that in sighted individuals, adult‐like audio‐haptic integration develops around 13–15 years of age, and remains stable until late adulthood. While early‐blind individuals, even at the youngest ages, integrate audio‐haptic information in an optimal fashion, late‐blind individuals do not. Optimal integration in low‐vision individuals follows a similar developmental trajectory as that of sighted individuals. These findings demonstrate that visual experience is not necessary for optimal audio‐haptic integration to emerge, but that consistency of sensory information across development is key for the functional outcome of optimal multisensory integration.     

Do emotional support and classroom organization earlier in the year set the stage for higher quality instruction?

Many teachers believe that providing greater emotional and organizational supports in the beginning of the year strengthens their ability to teach effectively as the year progresses. Some interventions, such as the Responsive Classroom (RC) approach, explicitly embed this sequence into professional development efforts. We tested the hypothesis that earlier emotional and organizational supports set the stage for improved instruction later in the year in a sample of third- and fourth-grade teachers enrolled in a randomized controlled trial of the RC approach. Further, we examined the extent to which the model generalized for teachers using varying levels of RC practices as well as whether or not teachers were in the intervention or control groups. Teachers' emotional, organizational, and instructional interactions were observed using the Classroom Assessment Scoring System ( Pianta, La Paro, & Hamre, 2008) on five occasions throughout the year. Results indicated a reciprocal relation between emotional and instructional supports. Specifically, higher levels of emotional support earlier in the year predicted higher instructional support later in the year. Also, higher levels of instructional support earlier in the year predicted higher emotional support later in the year. Classroom organization was not found to have longitudinal associations with the other domains across a year. This pattern was robust when controlling for the use of RC practices as well as across intervention and control groups. Further, teachers' use of RC practices predicted higher emotional support and classroom organization throughout the year, suggesting the malleability of this teacher characteristic. Discussion highlights the connection between teachers' emotional and instructional supports and how the use of RC practices improves teachers' emotionally supportive interactions with students.     

Comparative study of different welding wires on T92 welded joints

ABSTRACT

A comparative study of the effect of two different welding wires (W2 and Thermanit MTS-616 welding wire W1) on T92 welded joints has been made. Both wires showed good weldability and no defects in the welds were found. The hardness of the welded joint using W2 wire was lower than using W1. The toughness and high temperature (600°C) strength of the weld using W2 wire were higher than those using W1. The two welding wires produce joints having little difference in plasticity at room and high temperature. Large pores in both joints are related to the second phase of the larger particles in the matrix. The second phase of particles in the matrix easily caused cracks, which is unfavourable for the improvement of plasticity. Precipitation of the second phase of large particles in the matrix should be minimised for optimised welds.