阻断内侧前额叶皮质TrkB受体对大鼠认知和海马BDNF表达的影响

脑源性神经营养因子(brain-derived neurotrophic factor, BDNF)广泛参与了个体学习和记忆等认知功能, 通过与其酪氨酸激酶受体(tyrosine kinase, TrkB)特异性结合, 实现其多种神经生化功能。本研究观察了TrkB受体阻断剂ANA-12的慢性内侧前额叶皮质(medial prefrontal cortex, mPFC)注射对大鼠旷场行为、Morris水迷宫空间学习和逆反学习的影响。研究结果表明, mPFC的慢性BDNF阻断显著降低了大鼠在逆反学习测试中的逃离潜伏期和运动距离即增强了大鼠的逆反学习能力, 但不影响其旷场行为和水迷宫空间学习能力。同时, 慢性阻断mPFC-TrkB受体也并未导致大鼠海马BDNF蛋白含量的显著改变。这些结果提示, 对于大鼠的Morris水迷宫空间学习和逆反学习, mPFC-BDNF主要在逆反学习调节中发挥重要作用。这对于进一步探索海马和mPFC在调节个体认知功能中各自的作用及其潜在的相互关系提供了有力的证据和支持。     

自我控制资源与认知资源相互影响的机制:整合模型

尽管有学者认为自我控制资源和认知资源应该是两种独立的资源,但近期的研究却表明两种资源是互相影响的.以往研究从执行控制的角度解释两种资源为什么相互影响,但却没有指出两种资源如何影响执行控制,以及缺乏考虑神经机制和自我控制资源调节变量在其中的作用.为更系统地解释两种资源相互影响的机制,作者提出了一个整合模型,该模型指出:(1)两种资源相互影响的主要原因是两者都受到执行控制和前额叶皮层的影响;(2)个体进行自我控制或认知加工会消耗能量,产生心理疲劳,降低执行任务的动机,表现为前额叶皮层激活水平下降;(3)前额叶皮层激活不足进一步限制了执行控制在随后的自我控制和认知加工任务中的作用,因而影响后续自我控制或认知加工任务的表现;(4)自我控制资源调节变量通过提高个体对疲劳的耐受性、补充能量和提高动机等方法,使前额叶皮层和执行控制在完成前一阶段任务后仍然能够正常发挥作用,从而维持个体在后续自我控制或认知加工任务上的表现.未来的研究可考察自我控制资源与其他认知加工的关系;用动态的认知神经研究方法,建立前额叶皮层激活水平在前后两阶段任务之间的中介作用模型,以及研究自我控制资源调节变量的神经机制.     

认知灵活性对概率类别学习的影响

本研究采用“数字-字母转换任务”区分高低认知灵活性者, 构建概率配对模式相同但形式不同的两个概率类别学习任务, 借助ERP技术探讨认知灵活性对概率类别学习任务的作用特点与机制。结果发现, 本研究的两个任务中, 高认知灵活性组的规则习得水平均优于低认知灵活性组, 认知灵活性能促进概率类别的学习。同时, 对不同学习阶段的ERPs分析结果显示, 高认知灵活性者在概率类别学习中的优势源于反馈加工过程。     

熟练和非熟练中英双语者不同认知控制成分的比较

使用面孔任务考察熟练中英双语者和非熟练中英双语者在不同认知控制成分上的差异。被试为60名大学生。结果表明,熟练中英双语者在抑制控制和转换上的反应时消耗量均显著小于非熟练中英双语者,但在反应抑制上的反应时消耗量与非熟练中英双语者没有显著差异。该结果说明,二语熟练程度越高,中英双语者的认知灵活性(转换)和抑制控制(干扰控制)能力就越强;但是二语熟练程度对反应抑制能力没有明显的影响。由此可以推测,二语学习能促进中英双语者的认知灵活性(转换)和抑制控制(干扰控制)能力,但是,二语学习对中英双语者的反应抑制能力没有明显的促进作用。     

情绪状态对不同年龄儿童定势转换的影响

采用情绪影片引发情绪的方法,考察64名8~12岁儿童在正负情绪状态下定势转换能力的表现。研究为4(年龄)×2(情绪)×3(重复转换条件:重复、短时转换、长时转换)3因素重复测量混合设计。结果表明,情绪状态对任务转换产生了影响,可能是积极情绪比消极情绪对任务定势的长时转换削弱更大。不同年龄的儿童在这两种任务转换条件中没有出现显著的年龄差异,说明8~12岁儿童均已具备在两个任务之间进行即时转换的能力。     

慢性应激损害大鼠学习记忆且抑制海马及额叶FGF2蛋白表达

慢性应激能够影响学习和记忆等认知功能。海马和额叶是与学习和记忆联系密切的脑区, 参与信息的获得、保持及提取。碱性成纤维生长因子(FGF2)对神经元发生、存活以及损伤修复具有重要促进作用, 目前成为神经系统退行性疾病相关研究的热点。本研究旨在探索慢性应激如何影响大鼠学习和记忆能力, 以及这一过程中FGF2蛋白在海马和额叶中表达的改变。实验中将16只雄性SD大鼠随机分为对照组和慢性应激组, 采用慢性不可预见温和刺激建立大鼠慢性应激模型, 通过Morris水迷宫实验及Y迷宫实验检测学习与记忆功能的改变, 并对海马及额叶中FGF2蛋白的表达情况进行Western blot及免疫组织化学检测。结果发现, 5周慢性应激导致大鼠学习和记忆能力受损, 海马及额叶FGF2蛋白表达下调。因此认为, FGF2蛋白可能参与慢性应激损害学习记忆能力的机制, 提示FGF2可能是诊断和治疗神经系统退行性病变的分子靶目标。     

权力感的无意识启动:方法研究*

情境性启动法是对权力感进行内隐社会认知研究的重要方法。本研究首先对权力情境性启动的两种启动方法(概念启动和定势启动)进行介绍,接着通过两个实验对两种启动方法在中文背景下的适用性和有效性进行了验证,认为中文材料的概念启动和定势启动是适用和有效的,可以作为国内权力社会认知研究中启动权力的方法。最后对权力概念启动和定势启动的研究范式、方法差异和内在机制进行了讨论。     

不同趋近动机强度积极情绪对认知控制的影响

情绪的动机维度模型认为, 积极情绪对认知加工的影响受其趋近动机强度的调节, 高、低趋近动机积极情绪对认知加工的影响不同。本研究运用情绪图片诱发被试高、低趋近动机积极情绪, 采用停止信号任务和任务转换作业考察了不同趋近动机强度积极情绪对认知控制的影响。结果发现：(1)与中性条件相比, 高趋近动机积极情绪促进了停止信号任务中Go任务和任务转换作业中重复任务的反应执行。(2)在停止信号任务中, 相对于中性条件, 低趋近动机积极情绪条件下的停止信号反应时显著缩短; 在任务转换作业中, 低趋近动机积极情绪条件下的反应时转换损失和错误率转换损失均显著降低, 而高趋近动机积极情绪条件下的反应时转换损失显著增加。因此, 积极情绪对认知控制的影响受其趋近动机强度的调节, 即低趋近动机积极情绪增强认知灵活性, 提高停止反应与任务转换的速度; 而高趋近动机积极情绪增强认知稳定性, 加快停止信号任务中Go任务和任务转换作业中重复任务的反应执行, 增加了反应时转换损失。     

梨状皮层或苍白球损毁对大鼠空间认知能力的影响

在Ｍｏｒｒｉｓ迷宫中,梨状皮层或苍白球损毁大鼠的空间认知作业成绩较显著低于控制组,搜索目标以趋向式策略为主,与正常大鼠搜索策略的差异提示：①梨状皮层和苍白球参与了空间认知加工;②在图认知系统中梨状皮层和苍白球居辅助层次。     

阶段转移事件对公平稳定性的影响

摘要：目前,组织公平的研究多集中于组织公平与组织结果变量之间关系,较少关注组织公平的稳定性。本文采取4（公平模式：公平控制/初始公平/不公平控制/初始不公平）×2（实验阶段：阶段1/阶段2）混合实验设计,探讨阶段转移事件对被试公平反应稳定性的影响。研究结果显示,公平对待导致积极的公平反应,不公平对待导致消极的公平反应;公平程序向不公平程序的转移导致对实验者信任和组织公民行为意向的评价显著降低;而不公平程序向公平程序的转移并没有导致对实验者信任和组织公民行为意向评价的显著增加,从而说明了公平反应的有限稳定性。     

The effect of striatal dopamine depletion and the adenosine A2A antagonist KW-6002 on reversal learning in rats

This study assessed whether dopamine in the dorsomedial striatum is necessary for flexible adaptation to changes in stimulus-response contingencies. As KW-6002 (Istradefylline), an adenosine A(2A) antagonist, improves motor deficits resulting from striatal dopamine depletion, we also tested for potential ameliorative effects of KW-6002 on dopamine depletion-induced cognitive deficits. Male Lister hooded rats were presented with two bowls, discriminable by either a textured covering on the outer surface, their scent or the bowl contents (digging media) in which bait was buried. Once they had learned in which bowl food was buried, the stimulus-response contingencies were reversed. In both phases (acquisition and reversal), the criterion for learning was defined a priori as six consecutive correct trials. Following depletion of dopamine in the dorsomedial striatum, acquisition of the discriminations was intact but there was an increase in the number of trials to attain criterion performance in the reversal phases, indicating an impairment in reversal learning. KW-6002 (1mg/kg bidaily for 10 days) non-specifically increased the number of trials to criterion at all stages of the test and in both controls (sham-operated) and dopamine-depleted rats. Chronic KW-6002 treatment did not improve the reversal deficits in dopamine-depleted rats. These findings suggest that dopamine transmission in the dorsomedial striatum is critical for the flexible shifting of response patterns and the ameliorative effects of KW-6002 following depletion of dopamine in the striatum may be restricted to motor functions without relieving deficits in response-shifting flexibility.     

Effects of acute restraint stress on set-shifting and reversal learning in male rats

Exposure to acute stress alters cognition; however, few studies have examined the effects of acute stress on executive functions such as behavioral flexibility. The goal of the present experiments was to determine the effects of acute periods of stress on two distinct forms of behavioral flexibility: set-shifting and reversal learning. Male Sprague-Dawley rats were trained and tested in an operant-chamber-based task. Some of the rats were exposed to acute restraint stress (30 min) immediately before either the set-shifting test day or the reversal learning test day. Acute stress had no effect on set-shifting, but it significantly facilitated reversal learning, as assessed by both trials to criterion and total errors. In a second experiment, the roles of glucocorticoid (GR) and mineralocorticoid receptors (MR) in the acute-stress-induced facilitation of reversal learning were examined. Systemic administration of the GR-selective antagonist RU38486 (10 mg/kg) or the MR-selective antagonist spironolactone (50 mg/kg) 30 min prior to acute stress failed to block the facilitation on reversal learning. The present results demonstrate a dissociable effect of acute stress on set-shifting and reversal learning and suggest that the facilitation of reversal learning by acute stress may be mediated by factors other than corticosterone.     

Differential effects of inactivation of the orbitofrontal cortex on strategy set-shifting and reversal learning

Different subregions of the rodent prefrontal cortex (PFC) mediate dissociable types of behavioral flexibility. For example, lesions of the medial or orbitofrontal (OFC) regions of the PFC impair extradimensional shifts and reversal learning, respectively, when novel stimuli are used during different phases of the task. In the present study, we assessed the effects of inactivation of the OFC on strategy set-shifting and reversal learning, using a maze based set-shifting task mediated by the medial PFC. Long–Evans rats were trained initially on a visual-cue discrimination to obtain food. On the subsequent day, rats had to shift to using a response strategy (e.g., always turn left). On Day 3 (reversal), rats were required to reverse the direction of their turn (e.g., always turn right). Infusions of the local anesthetic bupivacaine into the OFC did not impair initial visual discrimination learning, nor did it impair performance on the set-shift. In contrast, inactivation of the OFC did impair reversal learning; yet, these rats ceased using the previously acquired response rule as readily as controls. Instead, rats receiving OFC inactivations made a disproportionate number of erroneous arm entries towards the visual-cue, suggested that these animals reverted back to using the original visual-cue based strategy. These findings, in addition to previous data, further support the notion that the OFC and medial PFC play dissociable roles in reversal learning and set-shifting. Furthermore, the lack of effect of OFC inactivations on the set-shift indicates that this type of behavioral flexibility does not require cognitive operations related to reversal learning.     

Aged rats are impaired on an attentional set-shifting task sensitive to medial frontal cortex damage in young rats

Normal aging is associated with disruption of neural systems that subserve different aspects of cognitive function, particularly in the hippocampus and frontal cortex. Abnormalities in hippocampal function have been well investigated in rodent models of aging, but studies of frontal cortex function in aged rodents are few. We tested young (4–5 mo old) and aged (27–28 mo old) male Long-Evans rats on an attentional set-shifting task modified slightly from previous publication. After training on two problems in which the reward was consistently associated with the same stimulus dimension, and a reversal of one problem, a new problem was presented in which the reward was consistently associated with the previously irrelevant stimulus dimension (extradimensional shift [EDS]). Aged rats as a group were significantly impaired on the EDS, although some individual aged rats performed as well as young rats on this phase. In addition, some aged rats were impaired on the reversal, although a group effect did not reach significance in this phase. Impairment in neither reversal nor EDS was associated with impairments in spatial learning in the Morris water maze. Young rats with neurotoxic lesions of medial frontal cortex are also selectively impaired on the EDS. These results indicate that normal aging in rats is associated with impaired medial frontal cortex function. Furthermore, age-related declines in frontal cortex function are independent of those in hippocampal function. These results provide a possible basis for correlating age-related changes in neurobiological markers in frontal cortex with cognitive decline.     

Neuromagnetic correlates of intra- and extra-dimensional set-shifting

Set-shifting is essential to cognitive flexibility and relies on frontal lobe function. Previous studies have mostly focused on feedback processes following shifting rather than set-shifting itself. We designed an MEG paradigm without feedback to directly investigate the neural correlates of set-shifting. Adults (n = 16) matched one of two coloured images with a third stimulus, the target, by either the colour or shape dimension of the target. Half of the shift trials involved colour-to-colour or shape-to-shape (intra-dimensional: ID) shifting and the other half involved colour-to-shape or shape-to-colour (extra-dimensional: ED) shifting. MEG was continuously recorded on a 151 channel CTF system. We used beamforming to analyze responses to the first (shift) and the third (repeat) trials in each set. These trials were contrasted separately for ID and ED sets. Shift versus repeat trials showed larger MEG activations for intra-dimensional shifting in the right inferior frontal gyrus (BA 47), left medial frontal gyrus (BA 10) and right superior frontal gyrus (BA 9) as early as 100 ms, and in left middle frontal gyrus (BA 11) between 250–500 ms. Activations related to extra-dimensional shifting were detected in left inferior frontal gyrus (BA 44), left middle frontal gyrus (BA 11), and right middle frontal gyrus (BA 46) between 100 ms and 350 ms, followed by superior frontal gyrus (BA 8/BA 10) between 250–500 ms. Intra-dimensional and extra-dimensional shifting also activated bilateral and right parietal areas, respectively. This study establishes the location and timing of frontal and parietal activations during an intra-dimensional versus extra-dimensional shifting task.     

Serotonin transporter knockout rats show improved strategy set-shifting and reduced latent inhibition

Behavioral flexibility is a cognitive process depending on prefrontal areas allowing adaptive responses to environmental changes. Serotonin transporter knockout (5-HTT(-/-)) rodents show improved reversal learning in addition to orbitofrontal cortex changes. Another form of behavioral flexibility, extradimensional strategy set-shifting (EDSS), heavily depends on the medial prefrontal cortex. This region shows functional changes in 5-HTT(-/-) rodents as well. Here we subjected 5-HTT(-/-) rats and their wild-type counterparts to an EDSS paradigm and a supplementary latent inhibition task. Results indicate that 5-HTT(-/-) rats also show improved EDSS, and indicate that reduced latent inhibition may contribute as an underlying mechanism.     

Isolation rearing effects on probabilistic learning and cognitive flexibility in rats

Isolation rearing is a neurodevelopmental manipulation that produces neurochemical, structural, and behavioral alterations in rodents that in many ways are consistent with schizophrenia. Symptoms induced by isolation rearing that mirror clinically relevant aspects of schizophrenia, such as cognitive deficits, open up the possibility of testing putative therapeutics in isolation-reared animals prior to clinical development. We investigated what effect isolation rearing would have on cognitive flexibility, a cognitive function characteristically disrupted in schizophrenia. For this purpose, we assessed cognitive flexibility using between- and within-session probabilistic reversal-learning tasks based on clinical tests. Isolation-reared rats required more sessions, though not more task trials, to acquire criterion performance in the reversal phase of the task, and were slower to adjust their task strategy after reward contingencies were switched. Isolation-reared rats also completed fewer trials and exhibited lower levels of overall activity in the probabilistic reversal-learning task than did the socially reared rats. This finding contrasted with the elevated levels of unconditioned investigatory activity and reduced levels of locomotor habituation that isolation-reared rats displayed in the behavioral pattern monitor. Finally, isolation-reared rats also exhibited sensorimotor gating deficits, reflected by decreased prepulse inhibition of the startle response, consistent with previous studies. We concluded that isolation rearing constitutes a valuable, noninvasive manipulation for modeling schizophrenia-like cognitive deficits and assessing putative therapeutics.     

Switch detection in preschoolers' cognitive flexibility

The current study addressed the role of switch detection in cognitive flexibility by testing the effect of transition cues (i.e., cues that directly signal the need to switch or maintain a given task goal) in a cued set-shifting paradigm at 5 years of age. Children performed better, especially on switch trials, when transition cues were combined with traditional task cues (i.e., cues that directly signal the relevant task on a given trial) relative to conditions without transition cues. This effect was not influenced by explicit knowledge of transition cues or transition cue transparency, suggesting that transition cues did not need to be semantically processed to be beneficial. These findings reveal that young children’s difficulties in set-shifting situations stem partially from failures to monitor for the need to switch.     

Attentional set-shifting in fragile X syndrome

The ability to flexibly adapt to the changing demands of the environment is often reported as a core deficit in fragile X syndrome (FXS). However, the cognitive processes that determine this attentional set-shifting deficit remain elusive. The present study investigated attentional set-shifting ability in fragile X syndrome males with the well-validated intra/extra dimensional set-shifting paradigm (IED) which offers detailed assessment of rule learning, reversal learning, and attentional set-shifting ability within and between stimulus dimensions. A novel scoring method for IED stage errors was employed to interpret set-shifting failure in terms of repetitive decision-making, distraction to irrelevance, and set-maintenance failure. Performance of FXS males was compared to typically developing children matched on mental age, adults matched on chronological age, and individuals with Down syndrome matched on both mental and chronological age. Results revealed that a significant proportion of FXS males already failed prior to the intra-dimensional set-shift stage, whereas all control participants successfully completed the stages up to the crucial extra-dimensional set-shift. FXS males showed a specific weakness in reversal learning, which was characterized by repetitive decision-making during the reversal of newly acquired stimulus-response associations in the face of simple stimulus configurations. In contrast, when stimulus configurations became more complex, FXS males displayed increased distraction to irrelevant stimuli. These findings are interpreted in terms of the cognitive demands imposed by the stages of the IED in relation to the alleged neural deficits in FXS.     

Risky decision making and cognitive flexibility among online sports bettors in Nigeria

Online sports betting is a popular recreational activity in Nigeria. Like other forms of gambling, risk of pathological progression exists for gamblers who continue betting despite severe financial and psychosocial consequences. In the present study, we examined whether this population of gamblers shows deficits in decision making and cognitive flexibility that have been documented in Western gambling populations. Thirty-six online sports bettors and 42 non-gambling participants completed a version of the Iowa gambling task (IGT) and an established set-shifting task for the assessment of cognitive flexibility. The two groups did not differ significantly in the selection of disadvantageous decks on the IGT. In contrast, sports bettors committed significantly more errors on the set-shifting task than non-gambling control participants. As this performance deficit was not specific to trials requiring a set shift, it most likely resulted from gambling-related changes in general cognitive or motivational abilities that are required to successfully complete challenging mental tasks. While our results illustrate that findings from Western populations cannot automatically be generalised to other contexts, it should be noted that we focused on only one particular type of gambling and included mostly participants with mild gambling-related problems.