死亡的判定

死亡是生命的终结.死亡判定的标准在历史上经历了一个逐步深化的过程.1959年2位法国医学家首先提出了脑死亡的概念.但是什么是脑死亡,以及如何判定脑死亡是一个有争议的问题.1981年美国总统委员会提出了一个脑死亡的判定指标体系,并被一些国家立法接受.回顾了对死亡判定认识的历史过程.     

记忆源检测研究综述

该文围绕记忆信息源检测这一二十世纪80年代后出现的新的研究领域,着重介绍了有较大影响的信源检测框架理论及其在源记忆错觉和神经机制方面的主要研究成果,并最后对这一领域研究的理论意义和现实意义进行了讨论。     

共情的神经机制

共情是社会认知中不可或缺的一部分,是维系积极社会关系的社会动机因素。近年来,脑成像技术的发展为共情的神经机制研究开拓了新的视野,共情的神经机制研究取得了很大的进展。共情神经机制的研究主要包括共情的"表征共享"基础、共情的镜像神经元特征、共情调节的早期、晚期评价模型、共情的调节因素以及特殊个体的共情研究。在此基础上指出现有研究中存在的问题和未来研究的方向。     

IMAG(IN)ING THE BUDDHIST BRAIN: EDITORIAL INTRODUCTION

Buddhism has captured the imagination of many in the modern (Western) world. Recently, scientists have seemed eager to discover whether claims about Buddhist meditation can be verified experimentally. Brain research is beginning to produce concrete evidence that mental discipline and meditative practice can change the workings of the brain and allow practitioners to achieve different levels of awareness, as measurable for instance in reaction times to stimuli. The goal of this section of articles in Zygon is to address recent developments in this area. The contributions address a wide array of questions, although they certainly do not cover the whole ground of what one may consider “problems” of meditation. Yet, we believe that the issues addressed here have widespread implications and that they constitute a strong argument for the richness of the meditation domain.     

颅脑肿瘤切除术后硬膜外血肿的原因及预防

浅析颅脑肿瘤切除术后硬膜外血肿形成的原因及预防措施。回顾性分析本科室自2005年7月～2009年7月共计13例脑肿瘤术后硬膜外血肿发生的特点,所有病例血肿均发生于小脑幕上,其中7例位于额部,3例位于颞部,2例位于顶部,1例位于枕部;平均血肿量为(37.3±3.2)ml。脑肿瘤切除术后硬膜外血肿形成机制为多种原因所导致的颅内压及脑脊液动力学改变致硬脑膜与颅骨剥离有关。各环节采取相应预防措施及术后常规复查头颅CT是防治脑肿瘤术后非手术区域硬膜外血肿的关键。     

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。     

Eye movements reduce vividness and emotionality of “flashforwards”

Earlier studies have shown that eye movements during retrieval of disturbing images about past events reduce their vividness and emotionality, which may be due to both tasks competing for working memory resources. This study examined whether eye movements reduce vividness and emotionality of visual distressing images about feared future events: “flashforwards”. A non-clinical sample was asked to select two images of feared future events, which were self-rated for vividness and emotionality. These images were retrieved while making eye movements or without a concurrent secondary task, and then vividness and emotionality were rated again. Relative to the no-dual task condition, eye movements while thinking of future-oriented images resulted in decreased ratings of image vividness and emotional intensity. Apparently, eye movements reduce vividness and emotionality of visual images about past and future feared events. This is in line with a working memory account of the beneficial effects of eye movements, which predicts that any task that taxes working memory during retrieval of disturbing mental images will be beneficial.     

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.