Same face,same place,different memory: manner of presentation modulates the associative deficit in older adults

One of the more severe and consequential memory impairments experienced by older adults is the loss of the ability to form and remember associations. Although the associative deficit is often assumed to be unitary, memory episodes may contain different types of associations (e.g., item–item, item–context). Research in younger adults suggests that these different association types may involve different neural mechanisms. This raises the possibility that different association types are not equally affected by aging. In order to investigate this, the current study directly compared memory across item–item and item–context associations in younger and older adults by manipulating the manner of presentation of the associations. Results indicate that the associative deficit in aging is not uniform and that aging has a greater impact on item–context compared to item–item associations. The results have implications for theories of associative memory, age-related cognitive decline, and the functional organization of the medial temporal lobe in aging.     

阅读障碍儿童的形音捆绑缺陷及其脑神经机制

形音捆绑缺陷研究是国内外阅读障碍研究领域的一个新方向。本文阐述了形音捆绑加工的理论与定义,综述了国内外研究者经常采用的三种形音捆绑的研究范式:配对联想学习、变化检测范式和线索回忆任务,介绍并分析了各研究范式的优缺点、适用范围及主要研究发现。同时,综述与评价了国内外有关阅读障碍形音捆绑缺陷的脑机制研究的主要结论及不足。最后,本文讨论了现有研究在实验设计和理论上的贡献与不足,提出了今后的研究方向和改进建议。     

Brain regions involved in subprocesses of small-space episodic object-location memory: a systematic review of lesion and functional neuroimaging studies

Object-location memory (OLM) enables us to keep track of the locations of objects in our environment. The neurocognitive model of OLM (Postma, A., Kessels, R. P. C., & Van Asselen, M. (2004). The neuropsychology of object-location memory. In G. L. Allen (Ed.), Human spatial memory: Remembering where (pp. 143–160). Mahwah, NJ: Lawrence Erlbaum, Postma, A., Kessels, R. P. C., & Van Asselen, M. (2008). How the brain remembers and forgets where things are: The neurocognition of object-location memory. Neuroscience & Biobehavioral Reviews, 32, 1339–1345. doi:10.1016/j.neubiorev.2008.05.001) proposes that distinct brain regions are specialised for different subprocesses of OLM (object processing, location processing, and object-location binding; categorical and coordinate OLM; egocentric and allocentric OLM). It was based mainly on findings from lesion studies. However, recent episodic memory studies point to a contribution of additional or different brain regions to object and location processing within episodic OLM. To evaluate and update the neurocognitive model of OLM, we therefore conducted a systematic literature search for lesion as well as functional neuroimaging studies contrasting small-space episodic OLM with object memory or location memory. We identified 10 relevant lesion studies and 8 relevant functional neuroimaging studies. We could confirm some of the proposals of the neurocognitive model of OLM, but also differing hypotheses from episodic memory research, about which brain regions are involved in the different subprocesses of small-space episodic OLM. In addition, we were able to identify new brain regions as well as important research gaps.     

The influence of performance on action-effect integration in sense of agency

Sense of agency refers to the subjective feeling of being able to control an outcome through one’s own actions or will. Prior studies have shown that both sensory processing (e.g., comparisons between sensory feedbacks and predictions basing on one’s motor intentions) and high-level cognitive/constructive processes (e.g., inferences based on one’s performance or the consequences of one’s actions) contribute to judgments of sense of agency. However, it remains unclear how these two types of processes interact, which is important for clarifying the mechanisms underlying sense of agency. Thus, we examined whether performance-based inferences influence action-effect integration in sense of agency using a delay detection paradigm in two experiments. In both experiments, participants pressed left and right arrow keys to control the direction in which a moving dot was travelling. The dot’s response delay was manipulated randomly on 7 levels (0–480 ms) between the trials; for each trial, participants were asked to judge whether the dot response was delayed and to rate their level of agency over the dot. In Experiment 1, participants tried to direct the dot to reach a destination on the screen as quickly as possible. Furthermore, the computer assisted participants by ignoring erroneous commands for half of the trials (assisted condition), while in the other half, all of the participants’ commands were executed (self-control condition). In Experiment 2, participants directed the dot as they pleased (without a specific goal), but, in half of the trials, the computer randomly ignored 32% of their commands (disturbed condition) rather than assisted them. The results from the two experiments showed that performance enhanced action-effect integration. Specifically, when task performance was improved through the computer’s assistance in Experiment 1, delay detection was reduced in the 480-ms delay condition, despite the fact that 32% of participants’ commands were ignored. Conversely, when no feedback on task performance was given (as in Experiment 2), the participants reported greater delay when some of their commands were randomly ignored. Furthermore, the results of a logistic regression analysis showed that the threshold of delay detection was greater in the assisted condition than in the self-control condition in Experiment 1, which suggests a wider time window for action-effect integration. A multivariate analysis also revealed that assistance was related to reduced delay detection via task performance, while reduced delay detection was directly correlated with a better sense of agency. These results indicate an association between the implicit and explicit aspects of sense of agency.     

Multi-scale control influences sense of agency: Investigating intentional binding using event-control approach

Control exercised by humans through interactions with the environment is critical for sense of agency. Here, we investigate how control at multiple levels influence implicit sense of agency measured using intentional binding. Participants are asked to hit a moving target using a joystick with noisy control followed by an intentional binding task initiated by the target hitting action. Perceptual-motor level control was manipulated through noise in the joystick controller (experiment 1) and goal-level control in terms of feedback about successful hit (experiments 2a and 2b). In the first experiment, intentional binding increased with amount of joystick control only when goal was not achieved and independent otherwise suggesting that the two levels interact hierarchically. In the second experiment, the estimated duration was dependent on when participants knew about goal completion. The results are similar to those obtained with explicit measures of sense of agency indicating that multi-scale event control influences agency.     

Distortions of temporal integration and perceived order caused by the interplay between stimulus contrast and duration

Stimulus contrast and duration effects on visual temporal integration and order judgment were examined in a unified paradigm. Stimulus onset asynchrony was governed by the duration of the first stimulus in Experiment 1, and by the interstimulus interval in Experiment 2. In Experiment 1, integration and order uncertainty increased when a low contrast stimulus followed a high contrast stimulus, but only when the second stimulus was 20 or 30 ms. At 10 ms duration of the second stimulus, integration and uncertainty decreased. Temporal order judgments at all durations of the second stimulus were better for a low contrast stimulus following a high contrast one. By contrast, in Experiment 2, a low contrast stimulus following a high contrast stimulus consistently produced higher integration rates, order uncertainty, and lower order accuracy. Contrast and duration thus interacted, breaking correspondence between integration and order perception. The results are interpreted in a tentative conceptual framework.     

认知过程中的捆绑问题--认知神经科学的研究

捆绑问题是当前脑科学研究中的主要问题之一,近来已成为意识争论的焦点。该文结合国外对捆绑问题研究的最新成果,在概括介绍关于捆绑机制的主要理论的基础上,综述了捆绑问题与主要认知功能关系的研究,并指出不同认知过程中捆绑脑机制的精细化研究和一般性捆绑脑机制的系统化研究可能是今后这方面研究的重点。     

Contribution of temporal preparation and processing speed to simple reaction time in persons with Alzheimer’s disease and mild cognitive impairment

Temporal preparation was assessed in 15 Alzheimer’s disease (AD) patients, 20 persons with mild cognitive impairment (MCI) and 28 healthy older adults. Participants completed a simple reaction time task in which the preparatory interval duration varied randomly within two blocks (short versus long temporal window). Results indicated that AD and MCI patients had difficulty preparing for the shortest preparatory interval of the short temporal window. AD and MCI patients also had difficulty maintaining an optimal level of preparation up to 5 s within the short temporal window. These results suggest that AD and MCI patients might show difficulty preparing for rapidly occurring events and maintaining preparation over time. This phenomenon should be considered when using reaction time measures with such patients.     

前瞻记忆的神经机制：来自临床研究的证据

前瞻记忆是指对预定事件或行为的记忆。本文总结了前瞻记忆脑机制相关的文献,介绍了前额皮层、丘脑,内侧颞叶等脑区域在前瞻记忆中的作用,并通过分析注意缺陷多动障碍儿童、老年痴呆症患者、酒精依赖症和内侧颞叶癫痫患者前瞻记忆的表现,从临床角度深入探讨了前瞻记忆神经机制的问题。证据表明,前额皮层参与前瞻记忆的编码、提取和监控过程,与意向保持也有密切的关系;丘脑与意向的执行有关,并且与前额叶互动在前瞻记忆监控中起着重要的作用;内侧颞叶与编码来源的提取和意向的激活都有密切的关系。研究认为前额皮层在前瞻记忆加工过程中起着核心的作用,同时与丘脑、内侧颞叶等区域相互作用,共同成为前瞻记忆编码、保持、提取、执行的神经基础。     

视觉工作记忆中特征绑定关系的记忆机制

弱客体理论认为, 视觉工作记忆系统是由众多特征存储的子系统组成, 不同纬度的特征独立存储在相应的有限容量的子系统中, 相互之间不会竞争记忆资源。而对于特征之间绑定关系的记忆存在不同的观点。一种观点认为绑定关系的记忆需要注意维持, 因此绑定关系的记忆会占用到特征记忆的资源; 另一种观点认为绑定关系的记忆是自动发生的, 不需要注意的维持。本实验的目的是探究特征绑定关系的记忆是否是自动发生的。在实验中, 我们设计了两种任务, 一种任务是只记忆颜色, 另一种任务是记忆颜色跟位置及其之间的绑定关系, 并测试分析视觉工作记忆相关的ERP成分CDA。结果发现两种任务条件下的CDA波幅之间没有显著差异, 说明视觉工作记忆中的特征绑定是自动发生的。