Resting Frontal EEG Asymmetry and Personality Traits: A Meta‐analysis

Frontal asymmetry has been widely used as a marker of emotion, motivation, and psychopathology. When assessed during the resting state, it is regarded as an index of trait approach and withdrawal motivation. However, the replicability of these associations with personality is currently unclear. The present meta‐analysis seeks to provide a comprehensive quantitative review of the relationship between personality traits and resting electroencephalographic (EEG) frontal asymmetry. We distinguished five personality clusters: extraversion, neuroticism, impulsivity, anger, and defensiveness. Data from 79 independent samples with overall 5700 participants were included in the meta‐analysis. The results revealed that less than 0.4% of the variance in extraversion and neuroticism could be explained by resting frontal asymmetry. Similarly, a small effect was observed for trait anger, and a small‐sized to medium‐sized effect was observed for defensiveness, although the number of studies was very low. No significant effect emerged for impulsivity. The effects were further reduced after adjustment for publication bias. Given some evidence for heterogeneity, sub‐traits were analysed, and methodological moderators were investigated. Based on the results, we conclude that the validity of resting frontal asymmetry as a marker for personality is not supported. Finally, recommendations are given to increase the replicability of frontal asymmetry research. © 2019 European Association of Personality Psychology     

Extraversion modulates functional connectivity hubs of resting‐state brain networks

Personality dimension extraversion describes individual differences in social behaviour and socio‐emotional functioning. The intrinsic functional connectivity patterns of the brain are reportedly associated with extraversion. However, whether or not extraversion is associated with functional hubs warrants clarification. Functional hubs are involved in the rapid integration of neural processing, and their dysfunction contributes to the development of neuropsychiatric disorders. In this study, we employed the functional connectivity density (FCD) method for the first time to distinguish the energy‐efficient hubs associated with extraversion. The resting‐state functional magnetic resonance imaging data of 71 healthy subjects were used in the analysis. Short‐range FCD was positively correlated with extraversion in the left cuneus, revealing a link between the local functional activity of this region and extraversion in risk‐taking. Long‐range FCD was negatively correlated with extraversion in the right superior frontal gyrus and the inferior frontal gyrus. Seed‐based resting‐state functional connectivity (RSFC) analyses revealed that a decreased long‐range FCD in individuals with high extraversion scores showed a low long‐range functional connectivity pattern between the medial and dorsolateral prefrontal cortex, middle temporal gyrus, and anterior cingulate cortex. This result suggests that decreased RSFC patterns are responsible for self‐esteem, self‐evaluation, and inhibitory behaviour system that account for the modulation and shaping of extraversion. Overall, our results emphasize specific brain hubs, and reveal long‐range functional connections in relation to extraversion, thereby providing a neurobiological basis of extraversion.     

Effects of post-encoding wakeful rest and study time on long-term memory performance

Recent work shows that post-encoding wakeful rest, in contrast to a cognitive task delay period, supports memory performance. The present study aimed at investigating whether study time modulates the impact of post-encoding rest on delayed memory performance. Healthy young adults were allocated to one of two “study time” groups (fixed-paced vs. self-paced). Participants encoded two word lists. After immediate recall of one word list, participants wakefully rested for 8?min, after the other, they performed a visual problem solving task. A delayed recall took place at the end of the experimental session (Experiment 1) and again after 7 days (Experiment 1?+?2). We found that participants in the self-paced group outperformed those in the fixed-paced group. In Experiment 1, participants showed higher memory performances after 7 days in the resting condition independent of study time. No significant differences between post-encoding (rest vs. problem solving) and study time conditions were found in Experiment 2. Combined analyses of both experiments revealed that an additional recall (Experiment 1) supported memory retention in both post-encoding conditions. Our findings suggest that resting is beneficial over the long term, but only when the encoded information is repeatedly retrieved at the end of a learning session.     

语言功能偏侧化及其与利手、功能连接的关系

对大脑语言功能偏侧化的探索起始于早期对脑损伤病人的研究。现代脑影像学研究发现, 语言功能偏侧化涉及额叶、颞叶、扣带回、梭状回和辅助运动区等脑区。语言偏侧化与利手和静息态功能连接之间的关系表现为：右利手的语言优势位于左半球, 而左利手的则分布在左半球、右半球或两个半球; 语言功能偏侧化与利手系数、静息态半球内功能连接之间具有正相关关系, 与半球间功能连接呈负相关, 并且语言功能偏侧化与静息态功能连接之间的关系在左右利手个体之间存在差异。总之, 大脑语言功能偏侧化、利手和静息态功能连接三者之间存在相互影响, 基于脑连接和遗传机制的研究将有望揭示出其底层的神经生理机制。     

无意识活动与静息态脑能量消耗

静息态脑活动的研究关注个体在清醒、静卧、闭眼时脑的活动情况,大量实验证明静息状态下大脑仍进行着持续不断的信息加工活动,并且消耗大量能量。本文在阐述无意识活动特性以及总结静息态脑能量消耗研究的基础上,提出用无意识活动解释静息态脑能量消耗的观点,强调在研究无意识活动的心理意义的同时,还要研究无意识活动的神经机制及其生理表现。     

Brief wakeful resting can eliminate directed forgetting

When cued to intentionally forget previously encoded memories, participants typically show reduced recall of the memories on a later recall test. We examined how such directed forgetting is affected by a brief period of wakeful resting between encoding and test. Encoding was followed by a “passive” wakeful resting period in which subjects heard emotionally neutral music or perceived neutral pictures, or it was followed by an “active” distraction period in which subjects were engaged in counting or calculation tasks. Whereas typical directed forgetting was present after active distraction, the forgetting was absent after wakeful resting. The findings indicate that the degree to which people can intentionally forget memories is influenced by the cognitive activity that people engage in shortly after learning takes place. The results provide first evidence on the interplay between wakeful resting and intentional forgetting.     

低静息心率与反社会行为的关系

由于静息心率易测性, 对静息心率的研究成为研究攻击和犯罪行为生理机制的重要手段之一。研究发现低静息心率与多种反社会行为存有关, 无论是动物研究, 人类研究还是跨文化的研究都表明了这种关系的存在。但元分析的结果表明低静息心率与反社会行为之间关系的效应量只是中等水平。同时, 社会经济因素和人格因素对低静息心率与反社会行为之间的关系有影响。低静息心率可能与低恐惧或低唤醒的特质、去甲肾上腺素功能减弱、大脑右半球功能减弱等因素有关。     

阿尔兹海默症及轻度认知障碍静息态大尺度脑网络功能连接的改变

静息态功能磁共振成像作为非侵入性可视化成像方法, 且数据采集简便易行, 已成为探索阿尔兹海默症及轻度认知障碍脑功能变异的主要成像手段。近年来静息态研究显示在其前驱症状期轻度认知障碍阶段患者已显现出静息态脑网络的变异, 而阿尔兹海默症患者的网络改变更加弥散。研究发现随着病程推进, 患者显示出默认网络连接逐渐减弱以及额叶认知网络连接先增强后减弱的整体趋势。此外, 脑结构和功能网络的改变并非单向因果关系, 二者在病程进展中存在交互作用。未来研究可以从诊断的标志性神经通路、疗效的大尺度脑网络标记, 以及疾病的异质性等角度入手, 进一步探索静息态脑网络作为阿尔兹海默症诊断和病程监控指标的可能性。