趋近和回避动机的区分及其对心理病理学的影响

趋近和回避是动机的两种最基本形式, 反映着个体与环境的相互作用方式, 是个体适应环境的核心机能。回避动机保证了个体的生存, 趋近动机则促进个体的成长。两类动机系统在前额叶皮层呈不对称偏侧化分布, 趋近动机与左侧额叶皮层激活相连, 回避动机与右侧额叶皮层激活相连。Youngstorm 和Izard等认为两类动机系统失调可能与一系列的情绪和行为问题有关, 如躁狂、抑郁、焦虑和儿童多动症等。这一观点已得到一些相关研究和临床研究证实。建议未来研究关注趋近-回避动机区分与情绪和认知功能研究的融合, 进一步检验趋近-回避动机系统失调模型, 并加强趋近和回避动机系统的可塑性研究。     

客体工作记忆任务中大脑皮层活动的记忆负荷效应

利用128导事件相关电位技术,采用延迟匹配任务的实验范式,测查了20名正常被试完成不同负荷客体任务时的皮层慢电位（slow cortical potentials,简称sp成分）,实验发现：背侧前额叶在刺激呈现后的700ms到1400ms出现记忆负荷效应,高负荷任务诱发的sp成分显著负于低负荷任务;低负荷任务诱发的sp成分在左前额区（500~1800ms）、左前额-中央区（700~1800ms）、左中央-顶叶区（1000~1400s和1800~4800ms）、右前额区（1800~4800ms）和右前额-中央区（1400~4800ms）显著负于高负荷任务,出现记忆负荷效应,但这种负荷效应在左右大脑半球所反映的心理意义可能不同     

The neural basis of event-time introspection

We explored the neural mechanisms allowing humans to report the subjective onset times of conscious events. Magnetoencephalographic recordings of neural oscillations were obtained while human subjects introspected the timing of sensory, intentional, and motor events during a forced choice task. Brain activity was reconstructed with high spatio-temporal resolution. Event-time introspection was associated with specific neural activity at the time of subjective event onset which was spatially distinct from activity induced by the event itself. Different brain regions were selectively recruited for introspection of different event types, e.g., the bilateral angular gyrus for introspection of intention. Our results suggest that event-time introspection engages specific neural networks to assess the contents of consciousness. Subjective event times should therefore be interpreted as the result of complex interactions between introspection and experience networks, rather than as direct reproduction of the individual’s conscious state or as a mere post hoc interpretation.     

MRI对儿童难治性、局灶性癫痫的临床诊断及预后判断

癫痫外科的临床病理研究表明,儿童局灶性皮质发育不良(FCD)及海马硬化是儿童难治性局灶性癫痫常见的致病因素。但在术前的常规的MRI检查中,这些结构上的异常经常被忽视,从而造成延误诊断。临床医生在阅片判断上的失误可能是一个原因,但癫痫的影像专业知识的不全面是重要因素。本文结合MRI技术在癫痫临床诊断领域的应用进展,阐述了儿童难治性、局灶性癫痫患者MRI影像中可能出现的结构性病变;重点阐述了临床易于忽视的局灶性皮质发育不良(FCD)及海马硬化的MRI研究、应用进展。     

On the Correlation between Synchronized Oscillatory Activities and Consciousness

Recent experiments have shown that the amplitudes of cortical gamma band oscillatory activities that occur during anesthesia are often greater than amplitudes of similar activities that occur without anesthesia. This result is apparently at odds with the hypothesis that synchronized oscillatory activities constitute the neural correlate of consciousness. We argue that while synchronization and oscillatory patterning are necessary conditions for consciousness, they are not sufficient. Based on the results of a binocular rivalry study of Fries et al. (1997), we propose that the degrees of oscillatory strength and synchronization of neuronal activities determine the degree of awareness those activities produce. On the other hand, the overal firing rates of neurons in cortical sensory areas are not correlated with the degree of awareness the activities of those neurons produce. The results of the experiment of Fries et al. (1997) appear to conflict with the results of another binocular rivalry experiment, in which monkeys were trained to pull a lever in order to report which stimulus object was being perceived (Leopold & Logothetis, 1996). In the latter experiment, it was demonstrated that the firing rates of neurons in striate cortex did not change during perceptual alterations, while 90% of neurons in inferior and superior temporal cortices changed their firing rate when the perceived image changed. This result led to the conclusion that activities in temporal cortex are correlated with visual awareness, but those in striate cortex are not. We argue that activities in temporal cortex contribute little, if anything, to perceptual awareness, and that their primary function is computational. Thus the correlation between the firing rates of neurons in these areas and the responses of the monkeys is due to the recognition of a particular stimulus object, which in turn is due to the computations made there.     

客体与空间工作记忆的分离：来自皮层慢电位的证据

利用128导事件相关电位技术,采用延迟匹配任务的实验范式,测查了16名正常被试在完成客体任务和空间任务时的皮层慢电位（slow cortical potentials,简称sp成分）,实验发现：在后部脑区,客体工作记忆与空间工作记忆在慢波活动的时间上存在分离,空间任务更早的诱发出负sp成分,并且空间任务激活更多的后部脑区;左下前额叶在客体工作记忆任务与空间工作记忆任务中都有激活,并且激活强度不存在显著差异;背侧前额叶主要负责客体信息的保持与复述,但左右背侧前额叶的激活强度存在不对称性。