Does frontal brain activity mediate the effect of depression prevention in adolescents? A pilot study

We investigated whether (a) depression prevention was associated with depressive symptoms and medial-frontal alpha asymmetry in adolescents; (b) alpha asymmetry mediated the association between participation in a prevention program and depressive symptoms; and (c) gender affects these associations. In our randomised control group study, we compared a universal prevention program (n = 40 adolescents, 14 females) with a non-intervention control condition (n = 39 adolescents, 20 females) in German secondary school students (mean age: 13.53 years, SD = 0.53). We collected data at baseline, post-intervention, 6-month, and 12-month follow-up using the Self-Rating Questionnaire for Depressive Disorders (SBB-DES) and resting medial-frontal alpha activity on F3 and F4. We found that girls benefitted from participating in the prevention program in regards to their depressive symptoms at 12-month follow-up but not alpha asymmetry. In boys, participation in the prevention program was associated with their alpha asymmetry at 6-month follow-up but not their depressive symptoms. Alpha asymmetry did not mediate the effects of the prevention program on depressive symptoms in either gender. Although participation in the prevention program was associated with both depressive symptoms and alpha asymmetry, those associations seem independent from each other. Possible explanations for this result pattern are discussed.     

医管、医患双重博弈研究

在中国,老百姓"看病难,看病贵"问题已饱受各方诟病多时,政府不断出台的政策却收效甚微。通过分析医疗机构、管制者和患者所面临的风险与收益、行为与选择、医疗机构与管制者之间的重复博弈,医疗机构与患者之间的一次性博弈,提出医疗机构与管制者、医疗机构与患者的双重博弈假说。指出了"药价虚高"的根源以及解决的可能途径。     

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。     

关于上下视野不对称性的研究

该研究就国内外对上下视野不对称性的研究成果做了详细的阐述,主要包括上下视野的定义、上下视野不对称性的行为和神经机制方面的研究成果及当前所面临的问题,并在文章的最后提出自己的观点。     

European starlings are capable of discriminating subtle size asymmetries in paired stimuli

Small deviations from bilateral symmetry (fluctuating asymmetries) are cues to fitness differences in some animals. Therefore, researchers have considered whether animals use these small asymmetries as visual cues to determine appropriate behavioral responses (e.g., mate preferences). However, there have been few systematic studies of animals' abilities to visually discriminate such minor asymmetries. If the asymmetries cannot be discriminated, fluctuating asymmetry can not be a visual cue. Here, we report an investigation of European starlings' (Sturnus vulgaris) abilities to discriminate small size asymmetries. We trained starlings, through operant conditioning in a free-flight aviary, to discriminate achromatic, symmetric paired stimuli from size-matched asymmetric stimuli. By starting the learning process with a large asymmetry and progressing through sequential trials of decreasing asymmetry, we elucidated a behavioral limit to asymmetry discrimination. We found that starlings are capable of discriminating a 10% size asymmetry. There was weaker evidence for discrimination of 5% asymmetry but no evidence for signal discrimination at 2.5% size asymmetry. This level of asymmetry discrimination suggests that many size asymmetry cues in nature can be discriminated by birds. At each level of asymmetry discrimination, we also tested whether starlings could generalize their learned symmetry preference to unreinforced novel images. Consistent with previous findings, we found that starlings could generalize their symmetry preferences.     

Frontal and parietal EEG asymmetries interact to predict attentional bias to threat

Frontal and parietal electroencephalographic (EEG) asymmetries mark vulnerability to depression and anxiety. Drawing on cognitive theories of vulnerability, we hypothesise that cortical asymmetries predict attention to threat. Participants completed a dot-probe task in which bilateral face displays were followed by lateralised targets at either short (300 ms) or long (1050 ms) SOA. We also measured N2pc to face onset as an index of early attentional capture. At long SOA only, frontal and parietal asymmetry interacted to predict attentional bias to angry faces. Those with leftward frontal asymmetry showed no attentional bias. Among those with rightward frontal asymmetry those with low right parietal activity showed vigilance for threat, and those with high right parietal activity showed avoidance. Asymmetry was not related to the N2pc or to attentional bias at the short SOA. Findings suggest that trait asymmetries reflect function in a fronto-parietal network that controls attention to threat.     

Visual asymmetry revisited: Mind wandering preferentially disrupts processing in the left visual field

An emerging theory proposes that visual attention operates in parallel at two distinct time scales – a shorter one (<1 s) associated with moment-to-moment orienting of selective visuospatial attention, and a longer one (>10 s) associated with more global aspects of attention-to-task. Given their parallel nature, here we examined whether these comparatively slower fluctuations in task-related attention show the same visual field asymmetry – namely, a right visual field bias – as often reported for selective visual–spatial attention. Participants performed a target detection task at fixation while event-related potentials (ERP) time-locked to task-irrelevant visual probes presented in the left and right visual fields were recorded. At random intervals, participants were asked to report whether they were “on-task” or “mind wandering”. Our results demonstrated that sensory attenuation during periods of “mind wandering” relative to “on-task”, as measured by the visual P1 ERP component at electrodes sites contralateral to the stimulus, was only observed for probes presented in the left visual field. In contrast, the magnitude of sensory gain in the right visual field was insensitive to whether participants were “on-task” or “mind wandering”. Taken together, our results support the notion that task-related attention at longer time scales and spatial attention at shorter time scales affect the same underlying mechanism in visual cortex.     

Functional mapping of left parietal areas involved in simple addition and multiplication. A single‐case study of qualitative analysis of errors

All electrostimulation studies on arithmetic have so far solely reported general errors. Nonetheless, a classification of the errors during stimulation can inform us about underlying arithmetic processes. The present electrostimulation study was performed in a case of left parietal glioma. The patient's erroneous responses suggested that calculation was mainly applied for addition and a combination of retrieval and calculation was mainly applied for multiplication. The findings of the present single‐case study encourage follow up with further data collection with the same paradigm.     

Reduced asymmetry in motor skill learning in left-handed compared to right-handed individuals

Hemispheric specialization for motor control influences how individuals perform and adapt to goal-directed movements. In contrast to adaptation, motor skill learning involves a process wherein one learns to synthesize novel movement capabilities in absence of perturbation such that they are performed with greater accuracy, consistency and efficiency. Here, we investigated manual asymmetry in acquisition and retention of a complex motor skill that requires speed and accuracy for optimal performance in right-handed and left-handed individuals. We further determined if degree of handedness influences motor skill learning. Ten right-handed (RH) and 10 left-handed (LH) adults practiced two distinct motor skills with their dominant or nondominant arms during separate sessions two–four weeks apart. Learning was quantified by changes in the speed–accuracy tradeoff function measured at baseline and one-day retention. Manual asymmetry was evident in the RH group but not the LH group. RH group demonstrated significantly greater skill improvement for their dominant-right hand than their nondominant-left hand. In contrast, for the LH group, both dominant and nondominant hands demonstrated comparable learning. Less strongly-LH individuals (lower EHI scores) exhibited more learning of their dominant hand. These results suggest that while hemispheric specialization influences motor skill learning, these effects may be influenced by handedness.