Social brain development and the affective consequences of ostracism in adolescence

Recent structural and functional imaging studies have provided evidence for continued development of brain regions involved in social cognition during adolescence. In this paper, we review this rapidly expanding area of neuroscience and describe models of neurocognitive development that have emerged recently. One implication of these models is that neural development underlies commonly observed adolescent phenomena such as susceptibility to peer influence and sensitivity to peer rejection. Experimental behavioural evidence of rejection sensitivity in adolescence is currently sparse. Here, we describe a study that directly compared the affective consequences of an experimental ostracism manipulation (Cyberball) in female adolescents and adults. The ostracism condition led to significantly greater affective consequences in the adolescents compared with adults. This suggests that the ability to regulate distress resulting from ostracism continues to develop between adolescence and adulthood. The results are discussed in the context of models of neurocognitive development.     

The effect of attending to motor overflow on its voluntary inhibition in young and older adults

Motor overflow refers to involuntary movement or muscle activity coinciding with voluntary movement. We examined whether 16 young adults (18-30 years) and 16 older adults (50-80 years) could voluntarily inhibit overflow. Participants performed a finger pressing task, exerting 50% of their maximal force. Overflow was concurrently recorded in the non-task hand. In the first condition, participants were not made aware of their motor overflow. Then participants, though informed of it, were asked to ignore their overflow. Finally, participants were requested to inhibit overflow with, and then without visual feedback, or vice versa. Overflow was exacerbated when older adults were unaware of it, and was reduced once they were informed. For young adults there was no significant difference between these conditions. Both Age Groups could significantly reduce overflow when so requested, independent of visual feedback. Thus motor overflow can be modulated by higher order cognitive control with directed attention.     

前瞻记忆的神经机制：来自临床研究的证据

前瞻记忆是指对预定事件或行为的记忆。本文总结了前瞻记忆脑机制相关的文献,介绍了前额皮层、丘脑,内侧颞叶等脑区域在前瞻记忆中的作用,并通过分析注意缺陷多动障碍儿童、老年痴呆症患者、酒精依赖症和内侧颞叶癫痫患者前瞻记忆的表现,从临床角度深入探讨了前瞻记忆神经机制的问题。证据表明,前额皮层参与前瞻记忆的编码、提取和监控过程,与意向保持也有密切的关系;丘脑与意向的执行有关,并且与前额叶互动在前瞻记忆监控中起着重要的作用;内侧颞叶与编码来源的提取和意向的激活都有密切的关系。研究认为前额皮层在前瞻记忆加工过程中起着核心的作用,同时与丘脑、内侧颞叶等区域相互作用,共同成为前瞻记忆编码、保持、提取、执行的神经基础。     

对威胁刺激的注意偏向：注意定向加速还是注意解除困难？

对威胁刺激的注意偏向普遍存在。注意定向加速和注意解除困难在不同阶段对注意偏向产生影响。威胁刺激属性、呈现时间以及被试特征是重要的调节因素。以杏仁核为核心的杏仁核?前扣带回网络可能是注意定向加速的神经基础, 而以眶额叶为中心的前额叶皮层可能是注意解除的神经基础。未来还需要就注意定向加速与注意解除困难的关系、注意偏向的调节机制以及其神经基础做更深入的研究。     

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。     

大脑视知觉调控的神经机制

大脑的知觉加工并非单纯由外部刺激驱动,而是存在自上而下的知觉调控。尽管这一现象被大量实验研究证实,但其神经机制仍然是认知神经科学研究的重要问题。本研究系统介绍了知觉调控的神经基础、实现形式、研究范式,及其理论模型,分析指出了当前研究面临的主要问题,并对未来的研究进行了展望,以期促进该问题研究的进一步开展。     

早期应激对情绪调节的影响及其神经机制

在个体生命早期遭遇的长期或重大的应激经历会显著增加个体罹患抑郁、焦虑等心理疾患的风险, 而情绪调节能力的损伤是引发这些心理疾患的重要因素之一。以人类为对象的行为实验和调查研究表明, 早期应激不仅会影响日常生活中情绪调节策略的使用, 还会对情绪调节能力造成影响, 其影响方向可能与早期应激的严重程度有关。目前, 大部分研究表明严重的早期应激会损伤情绪调节能力, 但中度的早期应激也可能提高情绪调节能力。更为整合性的研究表明情绪调节能力中介了早期应激和各类疾患之间的关系。进一步, 我们从神经层面上阐述了早期应激对情绪调节相关脑区和神经环路的影响。未来研究应当注意控制无关变量, 进一步探究不同早期应激对于情绪调节的影响。     

前额叶在老年阶段的可塑性及相关机制

大量研究表明, 前额叶的结构和功能更容易受年老化影响; 然而, 近年来的研究发现, 前额叶的结构和功能在老年阶段具有一定的可塑性。对老年人进行认知训练, 能够延缓前额叶皮层厚度的萎缩, 提高白质完整性, 改善神经网络的功能连接和分化, 并可能通过调节多巴胺系统的活动改变前额叶皮质和皮质下结构的功能激活模式。有氧锻炼能够改善心脑血管功能, 保护和促进神经元的存活和生长, 引起前额叶灰质、白质体积的增加及功能激活的变化。认知训练与有氧锻炼等相结合的整合性训练不仅引起前额叶及相关认知功能的改变, 而且具有更好的生态学效度, 使老年人日常认知能力和生活质量得到提高。未来研究应采用多种技术手段, 从多个层面理解老年阶段前额叶的可塑性及相关机制; 加强对与前额叶关系密切的多种认知功能可塑性神经机制的研究; 并重视与整合性训练有关的前额叶可塑性。     

双价效应及其认知机制

任务转换时, 如果一个刺激不仅包含当前任务的特征还包含另一任务的关联特征, 这样的刺激被称为双价刺激。双价刺激能影响个体对单价刺激的加工, 使个体对后续所有单价刺激的反应减慢, 这种现象被称为双价效应(bivalency effect)。研究者发现双价效应具有一定的普遍性和稳定性。对双价效应的理论解释主要有情境捆绑说和基于经验的预测模型。双价效应的产生与额外视觉特征的提取及自上而下的认知控制调整有关, 前者主要与颞-顶联合区的激活有关, 后者主要与背侧前扣带回以及前辅助运动区的激活相关。     

The adolescent brain

Adolescence is a developmental period characterized by suboptimal decisions and actions that give rise to an increased incidence of unintentional injuries and violence, alcohol and drug abuse, unintended pregnancy and sexually transmitted diseases. Traditional neurobiological and cognitive explanations for adolescent behavior have failed to account for the nonlinear changes in behavior observed during adolescence, relative to childhood and adulthood. This review provides a biologically plausible conceptualization of the neural mechanisms underlying these nonlinear changes in behavior, as a heightened responsiveness to incentives while impulse control is still relatively immature during this period. Recent human imaging and animal studies provide a biological basis for this view, suggesting differential development of limbic reward systems relative to top-down control systems during adolescence relative to childhood and adulthood. This developmental pattern may be exacerbated in those adolescents with a predisposition toward risk-taking, increasing the risk for poor outcomes.