Caudate nucleus-dependent response strategies in a virtual navigation task are associated with lower basal cortisol and impaired episodic memory

The present research examined the relationship between endogenous glucocorticoids, navigational strategies in a virtual navigation task, and performance on standard neuropsychological assessments of memory. Healthy young adult participants (N = 66, mean age: 21.7) were tested on the 4 on 8 virtual maze (4/8 VM) and standard neuropsychological tests such as the Rey-Osterrieth Complex Figure (RO) and the Rey Auditory Verbal Learning Task (RAVLT), which measure episodic memory. The 4/8 VM differentiates between navigational strategies, where participants either use a hippocampal-dependent spatial strategy by building relationships between landmarks, or a caudate nucleus-dependent stimulus–response strategy by automatizing a pattern of open and closed arms to learn the location of objects within the maze. Degree of stress was assessed by administering the Perceived Stress Scale (PSS) questionnaire. Cortisol samples were taken on two consecutive days upon waking, 30 min after waking, at 11 am, 4 pm, and 9 pm. There was a significant difference in basal levels of cortisol between spatial and response learners. Interestingly, response learners had significantly lower cortisol levels throughout the day. The two groups did not differ in terms of perceived stress as measured with the PSS questionnaire. Moreover, there was no significant correlation between PSS scores and salivary cortisol levels, indicating that the higher cortisol levels in the spatial group were not associated with greater perceived stress. In addition, participants who spontaneously used a spatial strategy performed significantly better on the RAVLT and RO. These data indicate that the cortisol levels in the spatial group may be optimal in terms of episodic memory performance whereas the cortisol levels in the response group may be associated with poorer memory. These results are suggestive of an inverted U-shaped curve describing the effects of basal levels of circulating cortisol on memory in young adults.     

‘I Remember When I Learned That!’ developmental and gender differences in children's memories of learning episodes

Eighty 4‐ to 9‐year‐old children answered factual knowledge questions in math, science and social studies during one‐on‐one interviews. Children indicated whether they had known or guessed each answer, and whether they (a) remembered the moment they learned the answer (episodic response) or (b) did not remember. For episodic responses, children provided memory narratives of learning episodes. One third of children's responses identified a learning episode. There was a developmental trend in which older children were more episodic than younger children, and when children knew and provided correct answers, there was a gender difference in which females were more episodic than males. Developmental and gender differences in the characteristics of memory narratives were also apparent. Copyright © 2010 John Wiley & Sons, Ltd.     

工作记忆负荷对注意捕获的影响研究

注意捕获研究对于探讨两种控制过程:自上而下的加工与自下而上的加工之间的关系具有重要的意义。本文通过检验不同工作记忆负荷对注意捕获的影响,探讨自上而下的认知控制对注意捕获的影响机制。本研究共包括二个实验:实验一比较了单、双任务条件对颜色干扰子注意捕获的影响;实验二探讨了不同工作记忆负荷对颜色干扰子注意捕获的影响。实验结果表明:工作记忆不仅在选择性注意任务中具有认知控制作用,而且这种作用能扩展到注意捕获现象中。注意捕获不是纯粹的刺激驱动的加工过程,它还受到自上而下的认知控制的调节。具体表现为,随着工作记忆负荷水平的增加,无关干扰子产生的注意捕获的程度增大。     

空间及言语工作记忆任务的情绪效应：来自ERP/ fMRI的证据

情绪与工作记忆的关系问题是情绪和认知研究领域中的子课题。根据加工效能理论, 负性情绪, 特别是焦虑对认知的影响通常被看作是通过影响工作记忆来完成的。因此, 探讨负性情绪是如何作用于工作记忆, 将有助于完善和发展情绪与认知的理论, 为心境障碍疾病的诊断、治疗及干预提供依据, 既具有学术价值又具有一定的临床意义。本论文在前人研究的基础上, 采用事件相关电位(ERP)和功能磁共振技术(fMRI), 系统地考察了情绪和工作记忆三个子成分(语音环路、视空间模板及中央执行器)间的关系。本论文抓住了当前的热点问题, 从情绪和认知的关系入手, 将脑成像、电生理和行为方面的研究有机结合, 将时间动态研究与空间定位研究相结合, 为情绪和工作记忆相互作用的神经机制提供独到的证据, 验证且发展了情绪和认知关系的奠基理论—— 加工效能理论。     

阿尔兹海默病患者中的范畴特异性语义记忆损伤

脑损伤可导致范畴特异性语义损伤, 即某一范畴的语义记忆选择性损伤或损伤更严重。阿尔兹海默病患者中的范畴特异性语义损伤可能来自不同范畴之间在熟悉度、词频、获得年龄、视觉复杂度、语义距离、加工要求以及所涉及的主要语义特征等方面的差别。然而, 有无生命范畴本身是否也是一个来源, 尚不清楚。进一步的研究不仅需要整合范畴途径和特征途径, 并区分语义记忆的存储和通达, 而且需要考查疾病严重程度如何影响语义记忆损伤模式。     

情绪记忆权衡效应:对复杂情绪刺激的记忆

情绪记忆研究最近一致发现了情绪记忆权衡效应,即人们对情绪事件的中心或核心特征的记忆增强,而对情绪事件的周围或背景特征的记忆受损.该效应证明情绪记忆具有选择性,情绪唤醒可以诱发出多种记忆选择性效应,并具有相当强的普遍性和稳定性,同时受较多主、客观因素的影响.相关理论逐步深入地阐述了该效应发生的可能机制,该效应在注意分配、编码以及编码后加工上的行为证据不断积累,但相关神经机制研究十分缺乏.未来研究应重视该效应的神经与遗传机制以及探讨面孔情绪诱发的记忆权衡效应等.     

Taking care of business? Grateful processing of unpleasant memories

In this study we investigated the impact of grateful processing on bringing closure to unpleasant emotional memories. After recalling an open memory, participants were randomly assigned to one of three writing conditions. For three sessions, participants wrote about neutral topics, the unpleasant event itself, or positive consequences from the event from their open memory that they felt they could now be grateful for. Results showed a significant effect of writing condition, and the pattern of means were as predicted: those in the grateful condition showed more memory closure, less unpleasant emotional impact, and less intrusiveness of the open memory than the other writing conditions. Grateful reappraisal of unpleasant memories may help individuals emotionally process these events, thus bringing emotional closure to these incidents. This might be one reason that grateful people tend to be happy people.     

The phonological store abandoned

Baddeley and Larsen (2007) argue that a number of key findings reported by Jones, Macken, and Nicholls (2004) and Jones, Hughes, and Macken (2006) pointing to shortcomings of the phonological store construct arise from the store being abandoned with long lists. In our rejoinder we point out that Baddeley and Larsen use a procedure in which retrieval from the supposed phonological storage would not—according to their own theory—have been possible, and we present theoretical, empirical, and logical problems with their “store abandonment” argument and highlight a number of difficulties associated with the interpretation of suffix and prefix effects. We conclude that our data are still problematic for the phonological store construct and suggest that a reformulation of short-term memory theory needs to embody (or indeed focus exclusively upon) perceptual and effector systems rather than bespoke storage modules.     

Applying an exemplar model to the artificial-grammar task: Inferring grammaticality from similarity

We present three artificial-grammar experiments. The first used position constraints, and the second used sequential constraints. The third varied both the amount of training and the degree of sequential constraint. Increasing both the amount of training and the redundancy of the grammar benefited participants' ability to infer grammatical status; nevertheless, they were unable to describe the grammar. We applied a multitrace model of memory to the task. The model used a global measure of similarity to assess the grammatical status of the probe and captured performance both in our experiments and in three classic studies from the literature. The model shows that retrieval is sensitive to structure in memory, even when individual exemplars are encoded sparsely. The work ties an understanding of performance in the artificial-grammar task to the principles used to understand performance in episodic-memory tasks.     

Forgotten but not gone: Context effects on recognition do not require explicit memory for context

Context effects on recognition memory provide an important indirect assay of associative learning and source memory. Neuropsychological studies have indicated that such context effects may obtain even if the contexts themselves are not remembered—for example, in individuals impaired on direct tests of memory for contextual information. In contrast, a recent study indicated that the effects of temporal context reinstatement on visual recognition obtain only when the contextual information itself was explicitly recollected. Here we report that the effects of reinstatement of spatial-simultaneous context on visual object recognition memory obtain irrespective of whether those context stimuli are explicitly recognized. We suggest that spatial-simultaneous context effects might be based on ensemble unitization of target and context stimuli at encoding, whereas temporal context effects may require recollective processes.