On Stage with Gunk

A structure is temporally gunky just in case all of its temporal parts have proper temporal parts. Joshua Stuchlik [2003] objects to the stage theory of persistence from temporal gunk by arguing that the former requires instantaneous entities while the latter precludes them. It is argued here that stage theory can accommodate temporal gunk by invoking short-lived persisting stages. However, a new and more serious problem for stage theory is not far to seek. The short-lived stages that are needed to accommodate gunk accord with stage theory only if they are appropriately qualitatively static. The problem is that, unless stage theory abandons much of its dialectical force, some of the required stages fail this condition. Thus, Stuchlik is right that gunk shows a large class of worlds not to be stages, but wrong about which worlds these are.     

Neural correlates of intertemporal choice in aggressive behavior

People often have to make decisions between immediate rewards and more long-term goals. Such intertemporal judgments are often investigated in the context of monetary choice or drug use, yet not in regard to aggressive behavior. We combined a novel intertemporal aggression paradigm with functional neuroimaging to examine the role of temporal delay in aggressive behavior and the neural correlates thereof. Sixty-one participants (aged 18–22 years; 37 females) exhibited substantial variability in the extent to which they selected immediate acts of lesser aggression versus delayed acts of greater aggression against a same-sex opponent. Choosing delayed-yet-more-severe aggression was increased by provocation and associated with greater self-control. Preferences for delayed aggression were associated with greater activity in the ventromedial prefrontal cortex (VMPFC) during such choices, and reduced functional connectivity between the VMPFC and brain regions implicated in motor impulsivity. Preferences for immediate aggression were associated with reduced functional connectivity between the VMPFC and the frontoparietal control network. Dispositionally aggressive participants exhibited reduced VMPFC activity, which partially explained and suppressed their preferences for delayed aggression. Blunted VMPFC activity may thus be a neural mechanism that promotes reactive aggression towards provocateurs among dispositionally aggressive individuals. These findings demonstrate the utility of an intertemporal framework for investigating aggression and provide further evidence for the similar underlying neurobiology between aggression and other rewarding behaviors.     

Culture,psychological proximity to the past and future,and self-continuity

The present research explores how culture influences individuals’ psychological proximity to the past and future, which may predict differences in perceived self-continuity across time. In Studies 1 and 2, we hypothesized and found that Chinese participants saw the past and future as more connected and subjectively closer to the present compared to Euro-Canadians. Following this, we expected and found in Studies 3 and 4 that Chinese participants perceived greater self-continuity over time than Euro-Canadians. Additionally, perceived closeness to the past mediated the effect of culture on past–present self-continuity, which subsequently predicted present–future self-continuity. Study 5 further documented a causal effect of perceived distance to the past on self-continuity. These results suggest that cultural differences in temporal attention to the past and future play a pivotal role in people's sense of self-continuity across time. This has important implications for temporal focalism, intertemporal discounting, and social interactions between Chinese and Euro-Canadians.     

第三方惩罚的神经机制：来自经颅直流电刺激的证据

第三方惩罚既是社会规范在群体得以维系的基石, 也是个体维护社会规范的体现。当前关注社会规范的神经研究大多基于第二方惩罚的独裁者或最后通牒实验框架, 缺乏对第三方维护社会规范过程中相关脑区活动的探索, 对这一过程的内在神经机制也不清楚。本文基于第三方惩罚的独裁者博弈框架, 对右侧背外侧前额叶区域(DLPFC)进行不同极性的经颅直流电刺激(tDCS), 同时依据第三方是否需要为其惩罚付出成本设计了零成本和有成本两个实验任务。结果发现, 第三方在零成本任务的情绪反应和惩罚显著受到tDCS设置的影响, 且阴极刺激显著提升了第三方的惩罚值, 这表明情绪机制对第三方惩罚有着重要影响。另外, 第三方在零成本和有成本任务中的惩罚差异在不同tDCS设置之间也存在显著差异, 这与第三方惩罚还受到自利机制影响的观点相符。本文率先为右侧DLPFC活动影响第三方惩罚提供了神经层面的证据, 且支持了第三方对社会规范的遵从与其负性情绪反应和自利加工密切相关的机制解释。     

Noninvasive brain stimulation over M1 and DLPFC cortex enhances the learning of bimanual isometric force control

Motor learning plays an important role in upper-limb function and the recovery of lost functionality. This study aimed to investigate the relative impact of transcranial direct current stimulation (tDCS) on learning in relation to the left primary motor cortex (M1) and left dorsolateral prefrontal cortex (DLPFC) during bimanual isometric force-control tasks performed with both hands under different task constraints. In a single-blind cross-over design, 20 right-handed participants were randomly assigned to either the M1 group (n = 10; mean age, 22.90 ± 1.66 years, mean ± standard deviation) or the DLPFC group (n = 10; mean age, 23.20 ± 1.54 years). Each participant received 30 min of tDCS (anodal or sham, applied randomly in two experiments) while performing the bimanual force control tasks. Anodal tDCS of the M1 improved the accuracy of maintenance and rhythmic alteration of force tasks, while anodal tDCS of the DLPFC improved only the maintenance of the force control tasks compared with sham tDCS. Hence, tDCS over the left M1 and DLPFC has a beneficial effect on the learning of bimanual force control.     

Testing the role of cognitive inhibition in physical endurance using high-definition transcranial direct current stimulation over the prefrontal cortex

The aim of this study was to clarify the role of the prefrontal cortex (PFC) in physical effort regulation. We hypothesized that the PFC would be progressively involved in physical endurance through the engagement of cognitive inhibition, which would be necessary to maintain effort by inhibiting fatigue-related cues. This hypothesis was examined using a double-blind, sham-controlled, within-subjects study (N = 20) using high-definition (HD) transcranial direct current stimulation (tDCS) over the right dorsolateral prefrontal cortex (dlPFC). Participants had to maintain a knee extensor contraction at 30% of their maximal force while simultaneously performing an Eriksen flanker task to evaluate their inhibition performance during the task. Anodal stimulation of the dlPFC influenced response to the cognitive task during exercise, as seen by slower response times and better accuracy. However, it did not lead to any measureable improvement in cognitive inhibition and did not influence endurance time. There was no correlation between cognitive inhibition and the maintenance of physical effort. This result does not indicate a relationship between cognitive inhibition and endurance performance. The contribution of the PFC in physical endurance could be explained through its involvement on decisional processes.     

社会排斥的心理行为特征及其脑机制

社会排斥损害个体基本的归属需要, 对个体的心理和生理会造成严重影响。根据需要威胁时间模型, 社会排斥后的心理和行为特征可以分为三个阶段。社交媒体的发展使社会排斥出现了新的心理和行为特征。近年来功能性磁共振成像研究发现, 突显网络和默认网络等网络中的一些核心脑区都参与了社会排斥各阶段的情绪和认知加工过程。未来研究应以需要威胁时间模型为基础, 以脑网络方法为手段, 探索社会排斥神经机制, 预测排斥后的心理和行为反应模式。