催产素影响条件化恐惧情绪加工的认知机制及神经基础

恐惧是一种与进化密切相关的情绪,对人类的生存与适应具有重要价值。过度的恐惧可能会导致恐惧症、焦虑症和创伤后应激障碍等病理性恐惧的产生。而催产素对各种病理性恐惧的干预和治疗具有重要的价值。因此,研究拟采用行为和fMRI技术,系统探究催产素影响条件化恐惧情绪加工的认知神经机制。重点关注:(1)催产素影响恐惧习得的认知神经机制;(2)催产素影响恐惧记忆巩固的认知神经机制;(3)催产素影响恐惧记忆再巩固的认知神经机制;(4)催产素影响恐惧消退的认知神经机制。这项研究的开展对于探究催产素影响条件化恐惧情绪加工的认知神经机制具有很高的科学价值,对于各种病理性恐惧的干预与治疗也具有重要的应用价值。     

催产素对社会决策行为的影响

大量的研究已经证明催产素对人类社会决策起着重要的调节作用。以往研究者采用多种实验范式用于探讨催产素对社会决策的影响, 研究内容主要包括合作与保护行为、道德行为、信任行为和慷慨行为。研究者已提出三种关于催产素的可能的作用机制用来解释观察到的实验结果, 三种理论各有侧重。未来的研究中应关注鼻喷催产素和受体基因多态性等生理机制、并考虑催产素影响社会决策行为的性别差异、建立更完善并可供检验的理论模型。     

催产素、孕激素和雌激素对厌恶的影响及其神经生理机制

厌恶是人和动物最基本的情绪之一, 起源于口腔对苦味(有毒)物质的排斥, 常伴有恶心呕吐和远离诱发刺激的强烈愿望, 具有回避潜在疾病威胁的功能。大量动物和人类研究表明, 催产素、孕激素和雌激素不同程度地影响核心厌恶刺激的感知、核心厌恶情绪的产生与表达、条件性厌恶习得和厌恶表情识别。三种激素主要通过作用于五羟色胺、γ-氨基丁酸、乙酰胆碱和谷氨酸等神经递质受体, 调节杏仁核、脑岛、前扣带回、壳核、梨状皮层、额中回等脑区活动, 影响厌恶加工。未来研究应当在准确测量激素水平和控制实验任务难度的基础上, 探究各激素对不同感觉通道厌恶加工的影响, 及其性别的调节作用; 同时结合脑成像技术和动物行为学, 明确各激素影响厌恶加工的神经内分泌机制。     

自我参照对情绪性记忆定向遗忘的影响

关于自我参照效应的研究大多从信息编码角度考察自我参照的加工优势, 但作为记忆过程的另一重要方面, 自我参照对遗忘影响的研究较少。遗忘自身经历的情绪性记忆是日常生活中的常见现象。研究采用项目法定向遗忘范式(item-method directed forgetting)考察了自我参照对情绪性记忆定向遗忘的影响。实验一和实验二的结果都表明参照方式会影响定向遗忘：自我参照条件下的材料会发生定向遗忘; 而他人参照条件下的材料不会发生定向遗忘, 两种参照方式下材料间区辨性的不同是导致这一现象的原因。此外, 实验二采用回忆测试发现：自我参照对不同效价的情绪性记忆定向遗忘产生了不同影响, 而自我提升(self-enhancement)动机在其中起着重要的调节作用。     

鸟类神经系统的长时程增强

揭示学习与记忆的神经机制已成为认知科学领域的一个重要研究方向。研究过程中需根据不同实验目的选用不同实验动物。LTP（long-term potentiation）是一种研究学习记忆突触基础的主要模型,其代表突触功能的可塑性。以往对LTP的研究主要集中于哺乳动物,但由于鸟类在生物进化上具有独特的地位及特有的学习记忆能力,因此通过某些鸟类行为模型将有利于对LTP特性及其与学习记忆相关性进行更深入的探索。     

学习和记忆的神经生物学

学习和记忆的神经生物学研究正处于非常令人振奋的阶段。人们以动物的行为研究来表明学习和记忆的特征和类别;用哺乳动物模型澄清和确定脑的基本记忆痕迹环路;根据人类记忆和脑研究的成果识别参与记忆的神经元系统;在无脊推动物和脊推动物中,对于记忆的神经元、神经化学、分子和生物物理的基础的了解已经有了良好的开端;基本的联想学习和神经元网络的理论研究和数学分析也进展迅速。因此,对于学习和记忆神经基础的这种新见解有可能在教育、治疗学习能力丧失和设计新的人工智能系统等方面都得到应用。     

项目特异性加工和关系加工对非熟练中-英双语者跨语言错误记忆的影响

采用DRM范式进行跨语言错误记忆的研究较为鲜见, 而且得出了许多不同的结果, 关于错误记忆跨语言产生的理论解释也是各执己见。研究以非熟练中-英双语大学生为被试, 采用DRM范式对非熟练中-英双语者的跨语言错误记忆进行了研究。在2个实验中, 分别探讨了项目特异性加工和关系加工条件下, 语义激活的不同水平对跨语言错误记忆的影响。结果发现：1)非熟练中-英双语者也存在跨语言的错误记忆; 2)在项目特异性加工和关系加工条件下, 相同语言内与不同语言间发生关键诱词的错误再认的结果是不同的; 3)只在项目特异性加工条件下, 长词表比短词表会诱发更多的对关键诱词的错误再认。研究结果支持了激活-监测理论。     

催产素及受体基因与社会适应行为

作为一种在哺乳动物分娩和泌乳中起神经调节作用的激素, 催产素(oxytocin, OT)在人类的母婴关系和社会关系中也发挥着重要作用。研究发现催产素及其受体基因与人类的社会适应行为关系密切。催产素会影响亲子依恋和父母教养行为, 也能促进人际信任及慷慨行为; 同时, 不同催产素受体(oxytocin receptor, OXTR)基因型的个体, 在亲子关系和一些亲社会行为方面都表现出了差异。来自于激素和基因水平的研究提示我们, 催产素及其受体基因可能是通过促进社会识别、调节共情以及降低恐惧、减缓焦虑来影响人类一系列的社会适应行为。未来的研究应考虑结合分子遗传学和神经科学的研究方法, 从基因－激素－行为三个层面系统的研究催产素影响社会行为的分子过程和认知神经过程。     

一致性、相关性对记忆生存优势效应的影响

对词语进行生存加工能提高记忆成绩,这种记忆的生存优势效应已得到不少研究的验证,且大多数研究表明生存优势是一种独特的编码方式(Nairne&Pandeirada,2011)。但是,Butler等人(2009)的研究结果表明实验中生存加工带来的记忆优势可能是一致性效应(即编码任务与编码的材料之间具有一致性)的作用。本文在2个实验中选用与生存和抢劫加工条件相关程度不同的词(高中低)为实验材料,采用生存加工、抢劫加工、愉悦度和有意学习为实验条件,研究一致性和相关性在记忆生存优势中的作用。结果发现:(1)生存条件下的记忆效果显著优于愉悦度条件和有意学习条件,这说明的确存在记忆的生存优势效应;(2)高生存相关词在生存加工条件下产生了记忆优势,而中、低生存相关词在2种加工条件下记忆成绩差异不显著,这说明加工条件的一致性只在一定程度上影响着记忆的生存优势效应;(3)词语自身的生存相关性没有表现出较强的记忆优势,当然这也可能与实验材料的词频有关。研究结果支持了Nairne和Pandeirada(2011)的观点。     

不同加工水平对内隐记忆和外显记忆中生存加工的影响

记忆的生存加工优势主要指生存情景下的记忆成绩好于其他情景下记忆成绩的一种优势效应。实验1采用生存加工研究范式,结合内隐记忆和外显记忆测试方法,考察了生存加工在内隐记忆和外显记忆中的表现。实验2结合不同的词语评估时间,进一步考察了不同加工水平对内隐记忆和外显记忆中生存加工的影响。结果发现,在内隐记忆中没有表现出生存加工优势,但是在外显记忆中出现了生存加工优势效应,并且外显记忆中的生存加工优势会受到加工水平的影响。     

Glucocorticoid-mediated effects of systemic oxytocin upon memory retrieval

During the last decade, a considerable amount of evidence has accumulated to show that oxytocin (OT) is involved with functions other than its classical roles in reproduction-associated processes, such as social recognition, maternal behavior and neuroendocrine regulation of the stress response. It has been shown, for instance, that post-training systemic administration of oxytocin in mice produces an amnestic effect on the step-through inhibitory avoidance. Since it is still unclear how systemic levels of OT may affect CNS memory processes, our aim here was to investigate the hypothesis that systemic OT effects on memory retrieval might be mediated through an oxytocin-induced decrease in glucocorticoid release. In our first experiment, we have found an amnestic effect of i.p. pre-test 0.4 microg/kg of OT upon memory retrieval in the inhibitory avoidance task (IA); this OT dose was shown to (a) significantly decrease plasma corticosterone levels when compared to the saline group, and (b) not to cause any anxiety effects by itself in a plus-maze task. At last, an ineffective-by-itself dose of dexamethasone was able to reverse the amnestic effect of this OT dose. Our results suggest that the amnestic effect of systemically administered oxytocin upon memory retrieval in the inhibitory avoidance task was probably caused by an oxytocin-induced decrease in glucocorticoid release from the adrenal gland.     

Time-dependent modulation of inhibitory avoidance memory by spermidine in rats

The polyamines, spermine, spermidine, and putrescine, are a group of aliphatic amines that may act as physiological modulators of N-methyl-D-aspartate (NMDA) receptors. Although the modulatory role of polyamines in NMDA receptor function has long been known, the effects of polyamines on learning and memory only recently began to be unraveled. In the present study, we investigated the effect of bilateral infusions of spermidine (0.02-2 nmol), a polyamine agonist, into the CA1 region of the rat dorsal hippocampus on inhibitory avoidance learning 30 min pre-training, immediately post-training, 6 h post-training, or 10 min pre-test. Bilateral microinjections of 0.2 nmol spermidine prolonged step-down latencies compared to the respective control group when administered 30 min pre-training or immediately post-training. These results provide evidence that the modulatory effects of spermidine on the acquisition and/or early consolidation of memory of inhibitory avoidance tasks in the hippocampus occur within a limited time window.     

Learning and memory in conditioned fear extinction: effects of D-cycloserine

This review addresses the effects of the cognitive enhancer D-cycloserine (DCS) on the memory processes that occur in conditioned fear extinction, which is the experimental model for exposure techniques to reduce clinical anxiety. All reported rat studies show an enhanced fear extinction effect when DCS is administered acutely before or shortly after extinction training. DCS also promotes the generalization of this fear extinction effect. In addition, DCS reduces some forms of relapse (reduced reinstatement, reduced spontaneous recovery), but not others (contextual renewal, rapid reacquisition). It is argued that this pattern of results is best explained by assuming that DCS promotes extinction learning to the background context, resulting in enhanced contextual inhibition. Four human studies have produced mixed results, but some methodological issues complicate the reported failures. It is concluded that DCS is a promising tool as an adjunct to extinction techniques in exposure treatment, but that more pre-clinical and clinical research is needed to fully characterize its behavioral consequences.     

Why do the effects of delaying reinforcement in animals and delaying feedback in humans differ? A working-memory analysis

Animal research has shown that reinforcement is substantially less effective when it is delayed, but in studies of human motor learning delays in providing feedback typically have much less effect. One possible explanation is that in human research participants know the response to be learned and can thus focus on it during the delay; that is not the case in experiments on animals. We tested this hypothesis using a task in which participants had minimal information on what movement was correct and found that, as in animal experiments, participants learned only when feedback was immediate. A second experiment confirmed that the effects of the delay depended on how many responses had to be held in working memory: the greater the memory load, the poorer the learning. The results point to the importance of activity during a delay on learning; implications for the teaching of motor skills are discussed.     

Intra-amygdala anxiogenic drug infusion prior to retrieval biases rats towards the use of habit memory

In a dual-solution plus-maze task that can be acquired using either hippocampus-dependent "cognitive/place" learning or dorsal striatal-dependent "habit/response" learning, pre-acquisition peripheral or intra-basolateral amygdala (BLA) injections of anxiogenic drugs result in the predominant use of response learning. The present experiments examined the effect of anxiogenic drug treatment on the relative use of multiple memory systems when administered prior to memory retrieval. Adult male Long-Evans rats were trained for two days (6 trials/day, 30s ITI) in a dual-solution plus-maze task to swim from the same start point (south) to an escape platform that was located in a consistent goal arm (west). On day three, prior to a memory retrieval probe trial from a novel start point (north), rats received a peripheral (0.03, 0.1 or 0.3 mg/kg), or intra-BLA (0.1 microg/0.5 microl) injection of the anxiogenic alpha(2)-adrenoreceptor antagonist RS 79948-197, or saline. Relative to saline controls, rats receiving either peripheral or intra-BLA infusions of RS 79948-197 predominantly displayed response learning on the probe trial. In an additional experiment peripheral (0.1 mg/kg) or intra-BLA (0.1 microg) drug injections administered prior to both acquisition and retrieval also resulted in the predominant use of response learning. The findings indicate that (1) similar to acquisition, peripheral injection of an anxiogenic drug prior to memory retrieval biases rats towards the use of habit/response memory, (2) intra-BLA infusions of an anxiogenic drug is sufficient to produce this modulatory effect of emotional state on memory retrieval, and (3) state-dependency does not appear to play a role in the effects of anxiogenic drug treatment on multiple memory system use. The findings may have implications for understanding the interaction between brain function, emotion, and the relative use of multiple memory systems in human psychopathology.     

On the relationship between autobiographical memory and perceptual learning

Although the majority of research on human memory has concentrated on a person's ability to recall or recognize items as having been presented in a particular situation, the effects of memory are also revealed in a person's performance of a perceptual task. Prior experience with material can make that material more easily identified or comprehended in perceptually difficult situations. Unlike with standard retention tests, effects of prior experience on a perceptual task do not logically require that a person be aware that he or she is remembering. Indeed, amnesic patients purportedly show effects of practice in their subsequent performance of a perceptual or motor task even though they profess that they do not remember having engaged in that prior experience. The experiments that are reported were designed to explore the relationship between the more aware autobiographical form of memory that is measured by a recognition memory test and the less aware form of memory that is expressed in perceptual learning. Comparisons of effects on perceptual learning and recognition memory reveal two classes of variables. Variables such as the level of processing of words during study influenced recognition memory, although they had no effect on subsequent perceptual recognition. A study presentation of a word had as large an effect on its later perceptual recognition when recognition memory performance was very poor as it did when recognition memory performance was near perfect. In contrast, variables such as the number and the spacing of repetitions produced parallel effects on perceptual recognition and recognition memory. Following Mandler and others, it is suggested that there are two bases for recognition memory. If an item is readily perceived so that it seems to "jump out" from the page, a person is likely to judge that he or she has previously seen the item in the experimental situation. Variables that influence ease of perceptual recognition, then, can also have an effect on recognition memory, so parallel effects are found. The second basis for recognition memory involves elaboration of a word's study context and depends on such factors as level of processing during study--factors that are not important for perceptual recognition of isolated words. Comparisons of perceptual recognition and recognition memory are shown to be useful for determining how a variable has its effect. Effects of study on perceptual recognition appear to be totally due to memory for physical or graphemic information. Results reported are also relevant to theories of perceptual learning. A single presentation of an item is shown to have large and long-lasting effects on its later perceptual recognition. At least partially, effects of study on perceptual recognition depend on the same variables as do effects on more standard memory tests.     

Why do the effects of delaying reinforcement in animals and delaying feedback in humans differ? A working-memory analysis

Animal research has shown that reinforcement is substantially less effective when it is delayed, but in studies of human motor learning delays in providing feedback typically have much less effect. One possible explanation is that in human research participants know the response to be learned and can thus focus on it during the delay; that is not the case in experiments on animals. We tested this hypothesis using a task in which participants had minimal information on what movement was correct and found that, as in animal experiments, participants learned only when feedback was immediate. A second experiment confirmed that the effects of the delay depended on how many responses had to be held in working memory: the greater the memory load, the poorer the learning. The results point to the importance of activity during a delay on learning; implications for the teaching of motor skills are discussed.     

Post-training glucose administration attenuates forgetting of passive-avoidance conditioning in 18-day-old rats.

The study of memory modulation in infant rats has typically focused on reminder/retrieval treatments involving reexposure to components of the internal or external training context. Rarely have studies employed pharmacological treatments to investigate the neurochemical substrates of memory storage in preweanling rats. The present study investigated the effect of 100 mg/kg of glucose, a common memory modulator in adult mammals, on memory for passive-avoidance conditioning in 18-day-old Sprague-Dawley rats. Subjects that were administered an immediate post-training injection of glucose performed significantly better, on a retention test 24 h following training, than those animals that received saline. The glucose group also performed comparably to a control group that was tested 10 min following training. These results are consistent with those of the memory modulation literature in adults and suggest that the rapid rate of forgetting in immature organisms may be the result of a deficiency in a general memory modulatory system.     

记忆编码策略对心境一致性记忆的调节作用

情绪对记忆的影响会受记忆编码策略的调节。本研究通过2个实验探讨编码策略对心境一致性记忆的调节作用。实验1和实验2均采用2（编码策略：提取练习策略、重复学习策略）×2（词性：消极词、中性词）的实验设计,分别探讨了不同记忆编码策略对普通大学生（实验1）和非临床抑郁大学生（实验2）心境一致性记忆的影响。结果发现：无论是被成功诱导出抑郁情绪的普通大学生,还是非临床抑郁倾向大学生,使用重复学习策略时回忆出的消极词均显著多于中性词,表现出显著的心境一致性记忆,而使用提取练习策略时回忆出的消极词和中性词没有显著性差异,未表现出心境一致性记忆。实验结果表明,记忆编码策略对心境一致性记忆具有调节作用,提取练习策略能够抑制心境一致性记忆。研究结果指明了心境一致性记忆的边界条件,并对非临床抑郁个体的学习与记忆具有重要的启示。