缺血后适应脑保护的耗散结构基础与脑缺血损伤的非线性特征

脑缺血损伤的机制十分复杂,主要内容涉及谷氨酸兴奋毒性、Ca2＋毒性、自由基损伤、一氧化氮损伤、炎性反应以及内质网和线粒体功能障碍等,这些复杂的机制网络具有耗散结构的非线性特征。近年发现缺血后适应可能通过P13K、Akt、MAPK、PKC等通路,KATP通道,抗凋亡等方式阻止或减轻损伤,从而实现脑保护,而形成一个复杂的信号转导体系。而对复杂的生命系统的研究起着指导作用的耗散结构理论是从更高水平层次研究复杂系统的系统科学,文中将从哲学的角度阐释缺血后适应产生大脑保护的耗散结构基础。     

Disfluency clusters in speakers with and without neurogenic stuttering following traumatic brain injury

PurposeAnalyze the characteristics and rate of disfluency clusters in adults with and without neurogenic stuttering after traumatic brain injury (TBI).MethodTwenty adults with TBI participated in this study, including 10 with neurogenic stuttering (Group B) and 10 without -stuttering (Group A). Disfluency clusters in speech samples were classified into three types: Stuttering-like (SLD), other (OD), and mixed (MIX).ResultsSpeakers with and without neurogenic stuttering produced the same mean number of disfluency clusters. In addition, the mean length of clusters did not differ between these speaker groups although the longest clusters did. The most frequently occurring cluster type for people with neurogenic stuttering was MIX and OD for people without stuttering. Although the speakers in Group A produced stuttering-like disfluencies, these never occurred together to form a SLD type cluster. For Group B, the starter units of the clusters were usually stuttering-like disfluencies, while for Group A, the starter units were mostly interruptions.ConclusionsCompared to non-stuttering speakers, stuttering after TBI did not increase the number of clusters, but rather lengthened them. In speakers with neurogenic stuttering, the number and length of clusters were related to the manifestation of other communication deficits, not to the frequency of stuttering-like disfluencies. Still, SLD clusters occurred only in those people with neurogenic stuttering. These findings raise questions about the nature of both neurogenic stuttering and the dynamics of disfluency clustering.     

A neurodevelopmental perspective on male violence

Research is increasingly documenting a neurobiological basis to violence. This review takes a neurodevelopmental perspective on the very small group of males who grow up to become persistent violent offenders. After outlining six criteria for what constitutes a neurodevelopmental disorder, the extent to which chronic violence meets these definitional criteria is examined, covering the fields of genetics, structural and functional brain imaging, and neuropsychology. Early health risk factors for violence are then outlined, including birth complications, minor physical anomalies, prenatal smoking and alcohol exposure, poor nutrition, lead exposure, and traumatic brain injury. Persistent adult violence is argued to originate in aberrant temperamental behavior in early childhood, to have a stable developmental trajectory, and to be associated with impaired education, social, and occupational functioning. Taken together, it is argued that chronic adult violence meets criterion for being conceptualized as having neurodevelopmental origins and that an important, but not sole, source of neural maldevelopment lies in prenatal and early postnatal risk factors. This review concludes with a recognition of the sociopolitical context within which a neurodevelopmental perspective on chronic violence sits, together with directions for future research, including whether a neurodevelopmental hypothesis is best applied to reactive as opposed to proactive aggression.     

Does transcranial direct current stimulation during writing alleviate upper limb freezing in people with Parkinson’s disease? A pilot study

Transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) can boost motor performance in Parkinson’s disease (PD) when it is applied at rest. However, the potential supplementary therapeutic effect of the concurrent application of tDCS during the training of motor tasks is largely unknown. The present study examined the effects of tDCS on upper limb motor blocks during a freezing-provoking writing task (the funnel task) requiring up- and down-stroke movements at alternating amplitudes. Ten PD patients and 10 age-matched controls underwent two sessions of writing combined with 20 min of anodal or sham tDCS on the left M1 in a randomized cross-over design. The primary outcome was the number of upper limb freezing episodes during five trials of the funnel task on a touch-sensitive tablet. PD patients showed a significant reduction in freezing episodes during tDCS compared to sham. No effects of tDCS were found for the amplitude, variability and speed of the strokes outside the freezing episodes. However, patients who reported freezing episodes in daily life (N = 6) showed a beneficial effect of tDCS on stroke characteristics. These results indicate a subgroup-dependent variability in response to non-invasive brain stimulation applied during the performance of motor tasks in PD. This warrants future studies to examine tDCS as an adjuvant tool for training programs aimed to reduce motor deficits related to freezing.     

Integrating brain science research with intelligence research

Understanding the possible causes of differences in intelligence is crucial if children are to achieve their full potential. Such understanding has been hampered until recently, however, because researchers who study intelligence have neglected recent findings in the brain sciences suggesting that the brain develops in response to environmental stimulation. These findings have seemed to contradict intelligence research that suggests that intellectual abilities are inherited. However, the findings from intelligence research and the brain sciences can be integrated if it is accepted that there are individual differences in the process by which the brain adapts to the environment, such that some people's brains are better at adapting than others'. The findings obtained from intelligence research are consistent with this integrated model. Such an integration has implications for better understanding the nature of intelligence.     

Human sexuality: how do men and women differ?

A large body of scientific research documents four important gender differences in sexuality. First, on a wide variety of measures, men show greater sexual desire than do women. Second, compared with men, women place greater emphasis on committed relationships as a context for sexuality. Third, aggression is more strongly linked to sexuality for men than for women. Fourth, women's sexuality tends to be more malleable and capable of change over time. These male-female differences are pervasive, affecting thoughts and feelings as well as behavior, and they characterize not only heterosexuals but lesbians and gay men as well. Implications of these patterns are considered.     

计算的脑机制研究进展

采用计算任务来探讨脑机制已成为国外研究大脑活动的重要领域。该文阐述了神经心理学和脑成像领域有关计算的脑机制研究。神经心理学及脑损伤的研究结果表明,大脑两侧顶下小叶和左前额叶与计算加工有关。ERP、PET和fMRI脑成像研究结果显示,数字命名与比较、心算、精算和估算等不同计算任务,其所激活的脑部位有所差异,但是大脑两侧顶下小叶和左前额叶可能是计算加工的主要脑部位。由于研究材料、方法和程序的不同,大脑皮层的广泛区域都有可能参与计算加工。     

近十年来情绪研究的回顾与展望

本文主要综述了近10年来,情绪心理学研究中所取得的进展和将来的研究趋向。首先介绍了情绪实验研究中实验材料的标准化和成像技术应用的发展概况;其次讨论了情绪智力的构成成分和情绪调节研究的进展;再次分析了情绪和认知之间的交互作用关系;最后探讨了感情系统的加工特征。     

视觉特征提取加工中的认知可塑性

本研究采用“加因素法”研究范式,通过两个实验分别检测20名飞行员和lO名老年被试及其相应控制组在视觉特征提取任务上的认知加工水平,旨在探讨视觉特征提取这一高水平视觉表象加工上的认知可塑性水平。研究结果表明,视觉特征提取加工既表现出了随外界系统训练而发生功能增强的练习效应,也表现出了随年老化过程而发生相应功能显著改变的年龄效应。研究提示,由于受大脑神经细胞活动特性改变的影响,视觉特征提取加工更多地表现出了可塑性或易变性相对较高的认知特性。结合相关的工作基础,研究结果还进一步证实高水平视觉认知加工所表现出的练习效应和年龄效应在大脑神经网络上的分布是不平衡的。本研究不仅对于揭示高水平视觉表象加工的认知特性具有重要的理论意义,而且在实践中对于建立飞行员、宇航员等特殊职业人员的选拔模型以及揭示飞行空间定向障碍的认知机制也具有重要的应用价值。     

发展性阅读障碍的视听时间敏感性缺陷及其脑神经机制

阅读是一个视听加工过程,阅读障碍的产生可能是过程中视听时间敏感性缺陷的结果。视听时间敏感性指个体对视觉和听觉刺激出现时间的感知能力,可通过同时性判断、时间顺序判断和视听整合考察。研究发现,阅读障碍者在这一能力上表现出行为和脑层面异常。而这些研究多是拼音文字背景,汉语文字下该领域研究相当少。未来需要丰富实验设计,扩大对汉语背景下视听时间敏感性研究,并以此开发干预手段,为阅读障碍的机制和治疗提供借鉴。