Age-related declines in general cognitive abilities of Balb/C mice are associated with disparities in working memory, body weight, and general activity

A defining characteristic of age-related cognitive decline is a deficit in general cognitive performance. Here we use a testing and analysis regimen that allows us to characterize the general learning abilities of young (3-5 mo old) and aged (19-21 mo old) male and female Balb/C mice. Animals' performance was assessed on a battery of seven diverse learning tasks. Aged animals exhibited deficits in five of the seven tasks and ranked significantly lower than their young counterparts in general learning abilities (aggregate performance across the battery of tasks). Aging added variability to common core performance (i.e., general learning ability), which translated into increased variability on the individual cognitive tasks. Relatedly, general learning abilities did not differ between the two ages among the best quartile of learners (i.e., cognitive abilities were spared in a subsample of the aged animals). Additionally, working memory capacity (resistance to interference) and duration (resistance to decay) accounted for significantly more of the variability in general learning abilities in aged relative to young animals. Tests of 15 noncognitive performance variables indicated that an increase in body weight (and an associated decrease in general activity) was characteristic of those aged animals which exhibited deficient general learning abilities. These results suggest the possibility that general cognitive deficits in aged animals reflect a failure of specific components of the working memory system, and may be related to variations in body weight and an associated decrease in activity.     

Variations in working memory capacity predict individual differences in general learning abilities among genetically diverse mice

Up to 50% of an individuals' performance across a wide variety of distinct cognitive tests can be accounted for by a single factor (i.e., "general intelligence"). Despite its ubiquity, the processes or mechanisms regulating this factor are a matter of considerable debate. Although it has been hypothesized that working memory may impact cognitive performance across various domains, tests have been inconclusive due to the difficulty in isolating working memory from its overlapping operations, such as verbal ability. We address this problem using genetically diverse mice, which exhibit a trait analogous to general intelligence. The general cognitive abilities of CD-1 mice were found to covary with individuals' working memory capacity, but not with variations in long-term retention. These results provide evidence that independent of verbal abilities, variations in working memory are associated with general cognitive abilities, and further, suggest a conservation across species of mechanisms and/or processes that regulate cognitive abilities.     

Effects and mechanisms of working memory training: a review

Can cognitive abilities such as reasoning be improved through working memory training? This question is still highly controversial, with prior studies providing contradictory findings. The lack of theory-driven, systematic approaches and (occasionally serious) methodological shortcomings complicates this debate even more. This review suggests two general mechanisms mediating transfer effects that are (or are not) observed after working memory training: enhanced working memory capacity, enabling people to hold more items in working memory than before training, or enhanced efficiency using the working memory capacity available (e.g., using chunking strategies to remember more items correctly). We then highlight multiple factors that could influence these mechanisms of transfer and thus the success of training interventions. These factors include (1) the nature of the training regime (i.e., intensity, duration, and adaptivity of the training tasks) and, with it, the magnitude of improvements during training, and (2) individual differences in age, cognitive abilities, biological factors, and motivational and personality factors. Finally, we summarize the findings revealed by existing training studies for each of these factors, and thereby present a roadmap for accumulating further empirical evidence regarding the efficacy of working memory training in a systematic way.     

Longitudinal attentional engagement rescues mice from age-related cognitive declines and cognitive inflexibility

Learning, attentional, and perseverative deficits are characteristic of cognitive aging. In this study, genetically diverse CD-1 mice underwent longitudinal training in a task asserted to tax working memory capacity and its dependence on selective attention. Beginning at 3 mo of age, animals were trained for 12 d to perform in a dual radial-arm maze task that required the mice to remember and operate on two sets of overlapping guidance (spatial) cues. As previously reported, this training resulted in an immediate (at 4 mo of age) improvement in the animals' aggregate performance across a battery of five learning tasks. Subsequently, these animals received an additional 3 d of working memory training at 3-wk intervals for 15 mo (totaling 66 training sessions), and at 18 mo of age were assessed on a selective attention task, a second set of learning tasks, and variations of those tasks that required the animals to modify the previously learned response. Both attentional and learning abilities (on passive avoidance, active avoidance, and reinforced alternation tasks) were impaired in aged animals that had not received working memory training. Likewise, these aged animals exhibited consistent deficits when required to modify a previously instantiated learned response (in reinforced alternation, active avoidance, and spatial water maze). In contrast, these attentional, learning, and perseverative deficits were attenuated in aged animals that had undergone lifelong working memory exercise. These results suggest that general impairments of learning, attention, and cognitive flexibility may be mitigated by a cognitive exercise regimen that requires chronic attentional engagement.     

Implicit statistical learning in language processing: Word predictability is the key

Fundamental learning abilities related to the implicit encoding of sequential structure have been postulated to underlie language acquisition and processing. However, there is very little direct evidence to date supporting such a link between implicit statistical learning and language. In three experiments using novel methods of assessing implicit learning and language abilities, we show that sensitivity to sequential structure – as measured by improvements to immediate memory span for structurally-consistent input sequences – is significantly correlated with the ability to use knowledge of word predictability to aid speech perception under degraded listening conditions. Importantly, the association remained even after controlling for participant performance on other cognitive tasks, including short-term and working memory, intelligence, attention and inhibition, and vocabulary knowledge. Thus, the evidence suggests that implicit learning abilities are essential for acquiring long-term knowledge of the sequential structure of language – i.e., knowledge of word predictability – and that individual differences on such abilities impact speech perception in everyday situations. These findings provide a new theoretical rationale linking basic learning phenomena to specific aspects of spoken language processing in adults, and may furthermore indicate new fruitful directions for investigating both typical and atypical language development.     

工作记忆对知觉类别学习的影响:问题与构想

人们学习将感知到的客体按照不同的标准或规则分类存储,即类别学习。而工作记忆作为多种认知加工的基础,对类别学习具有重要作用。基于已有研究,分别梳理了言语工作记忆和视空工作记忆对基于规则和信息整合类别结构的影响。目前,执行功能是否影响内隐类别学习系统、工作记忆负荷对内隐外显类别学习系统的影响是否一致还存在争议。此外,工作记忆影响知觉类别学习的认知加工阶段尚不清晰。未来的研究还需明确工作记忆负荷对内隐和外显类别学习的影响,进一步验证工作记忆影响类别学习的认知加工阶段假设的合理性。     

Thoughtful Friends: Executive Function Relates to Social Problem Solving and Friendship Quality in Middle Childhood

Abstract

The present study examined links between best friendship quality, social problem solving in response to a transgression and conscious control of behavior (i.e., executive function or EF). Eighty-one 7- to 10-year-olds answered questions about their best friendship quality and responses to friendship transgressions (i.e., interpretations, goals, and strategies they would endorse). They also completed a battery of EF tasks measuring working memory, inhibition, and shifting. Results revealed few relations between social problem solving and best friendship quality. Social problem solving related to EF abilities, with inhibition relating to fewer revenge goals and cognitive flexibility relating to more neutral interpretations. Better working memory related to worse best friendship quality. Finally, verbal IQ was a strong predictor of several positive social problem-solving interpretations, goals, and strategies. Results suggest cognitive abilities in EF and language may be important to consider during middle childhood in this period of advancing social problem solving and friendships.     

What cognitive abilities are involved in trail-making performance?

The cognitive abilities involved in the Connections (Salthouse, et al., 2000) version of the trail making test were investigated by administering the test, along with a battery of cognitive tests and tests of complex span and updating conceptualizations of working memory, to a sample of over 3600 adults. The results indicate that this variant of the trail making test largely reflects individual differences in speed and fluid cognitive abilities, with the relative contributions of the two abilities varying according to particular measure of performance considered (e.g., difference, ratio, or residual). Relations of age on trail making performance were also examined. Although strong age differences were evident in the Connections and working memory measures, with both sets of variables there was nearly complete overlap of the age differences with individual differences in speed and fluid cognitive abilities.     

Cross-modal working memory binding and L1-L2 word learning

The ability to create temporary binding representations of information from different sources in working memory has recently been found to relate to the development of monolingual word recognition in children. The current study explored this possible relationship in an adult word-learning context. We assessed whether the relationship between cross-modal working memory binding and lexical development would be observed in the learning of associations between unfamiliar spoken words and their semantic referents, and whether it would vary across experimental conditions in first- and second-language word learning. A group of English monolinguals were recruited to learn 24 spoken disyllable Mandarin Chinese words in association with either familiar or novel objects as semantic referents. They also took a working memory task in which their ability to temporarily bind auditory-verbal and visual information was measured. Participants’ performance on this task was uniquely linked to their learning and retention of words for both novel objects and for familiar objects. This suggests that, at least for spoken language, cross-modal working memory binding might play a similar role in second language-like (i.e., learning new words for familiar objects) and in more native-like situations (i.e., learning new words for novel objects). Our findings provide new evidence for the role of cross-modal working memory binding in L1 word learning and further indicate that early stages of picture-based word learning in L2 might rely on similar cognitive processes as in L1.     

Effects of working memory training in young and old adults

Many cognitive abilities, including working memory and reasoning ability, decline with progressing age. In this study, we investigated whether four weeks of intensive working memory training would enhance working memory and reasoning performance in an age-comparative setting. Groups of 34 young (19–36 years) and 27 older (62–77 years) adults practiced tasks representing the three functional categories in the facet model of working memory capacity: storage and processing, relational integration, and supervision. The data were compared to those of a young and an old active control group who practiced tasks with low working memory demands. A cognitive test battery measuring near and far transfer was administered before and after training. Both age groups showed increased working memory performance in the trained tasks and in one structurally similar, but nontrained, task. Young adults also improved in a task measuring word-position binding in working memory. However, we found no far transfer to reasoning in either age group. The results provide evidence that working memory performance can be improved throughout the life span. However, in contrast to a previous study in which each facet of working memory capacity was trained separately, the present study showed that training multiple functional categories simultaneously induces less transfer.     

Visuospatial working memory in Turner's syndrome

Turner's syndrome is a genetic disorder, specific to women, in which one of the X chromosomes is partially or completely deleted. This syndrome is associated with physical features such as short stature or failure in primary and secondary sexual development, together with a specific pattern of cognitive functions. It has been suggested that women affected by Turner's syndrome perform poorly in tasks measuring visuospatial abilities and have a verbal IQ significantly higher than performance IQ. Although this result has received strong empirical support, the nature of the visuospatial deficit is still unclear. Recent studies on visuospatial processes have highlighted that the underlying cognitive structure is more complex than previously suggested and several dissociations have been reported (e.g., visual vs spatial, sequential vs simultaneous, or passive vs active processes). In the present study we analyze in detail the characteristics of the visuospatial deficit associated with Turner's syndrome by presenting four young women with a comprehensive battery of tasks designed to tap all aspects of visuospatial working memory. Results confirm that Turner's syndrome is associated with a general visuospatial working memory deficit, but the pattern of performance of different cases can be different, with a greater emphasis on active visuospatial processes. and on either sequential or simultaneous spatial processes.     

Predicting environmental learning from spatial abilities: An indirect route

Relationships among spatial abilities, as assessed by a battery of psychometric tests and experimental tasks, and environmental learning, as assessed by a series of macrospatial tasks, were examined in two studies using confirmatory factor analysis with directional paths. The initial study indicated the utility of a five-factor model, one (general spatial ability) derived from psychometric tests, two (spatial-sequential memory and spatial perspective-taking latency) from experimental tasks, and two (topological knowledge and Euclidean direction knowledge) from measures of environmental learning. The best fitting path model further indicated that the spatial-sequential memory factor mediated the relationship between general spatial ability and topological knowledge, and that perspective-taking latency mediated the relationship between general spatial ability and Euclidean direction knowledge. The second study confirmed the five-factor path model using a different participant sample and environmental setting. The only failure to replicate involved the path between perspective-taking latency in the lab and Euclidean direction knowledge in the environment. Results indicate that the relationship between basic spatial abilities and environmental learning is significantly mediated by cognitive processes that can be assessed using laboratory tasks.     

Complex span tasks, simple span tasks, and cognitive abilities: A reanalysis of key studies

There is great interest in the relationships between memory span tasks and cognitive abilities. However, the causes underlying their correlation remain unknown. In the present article, five key data sets were reanalyzed according to two criteria: They must consider complex span tasks (so-called working memory [WM] tasks) and simple span tasks (so-called short-term memory [STM] tasks), and they must comprise cognitive ability measures. The obtained results offer several points of interest. First, memory span tasks should be conceived from a hierarchical perspective: They comprise both general and specific components. Second, the general component explains about four times the variance explained by the specific components. Third, STM and WM measures are closely related. Fourth, STM and WM measures share the same common variance with cognitive abilities. Finally, the strong relationship usually found between memory span tasks and cognitive abilities could be tentatively interpreted by the component shared by STM and WM--namely, the capacity for temporarily preserving a reliable memory representation of any given information.     

Why Higher Working Memory Capacity May Help You Learn: Sampling,Search, and Degrees of Approximation

Algorithms for approximate Bayesian inference, such as those based on sampling (i.e., Monte Carlo methods), provide a natural source of models of how people may deal with uncertainty with limited cognitive resources. Here, we consider the idea that individual differences in working memory capacity (WMC) may be usefully modeled in terms of the number of samples, or “particles,” available to perform inference. To test this idea, we focus on two recent experiments that report positive associations between WMC and two distinct aspects of categorization performance: the ability to learn novel categories, and the ability to switch between different categorization strategies (“knowledge restructuring”). In favor of the idea of modeling WMC as a number of particles, we show that a single model can reproduce both experimental results by varying the number of particles—increasing the number of particles leads to both faster category learning and improved strategy‐switching. Furthermore, when we fit the model to individual participants, we found a positive association between WMC and best‐fit number of particles for strategy switching. However, no association between WMC and best‐fit number of particles was found for category learning. These results are discussed in the context of the general challenge of disentangling the contributions of different potential sources of behavioral variability.     

Up-regulation of exploratory tendencies does not enhance general learning abilities in juvenile or young-adult outbred mice

"General cognitive ability" describes a trait that transcends specific learning domains and impacts a wide range of cognitive skills. Individual animals (including humans) exhibit wide variations in their expression of this trait. We have previously determined that the propensity for exploration is highly correlated with the general cognitive abilities of individual outbred mice. Here, we asked if inducing an increase in exploratory behaviors would causally promote an increase in animals' general learning abilities. In three experiments, juvenile and young-adult male CD-1 outbred mice were exposed to 12 novel environments starting at post-natal days 39 (juvenile) and 61 (young adult), after which they underwent a series of cognitive and exploratory tests as adults (beginning at post-natal day 79). Exposure to novel environments promoted increases in exploration (across multiple measures) on two different tasks, including an elevated plus maze. However, a subsequent test of general learning abilities (aggregate performance across five distinct learning tasks) determined that exposure to novel environments as juveniles or young-adults had no effect on general learning abilities in adulthood. Therefore, while exposure to novel environments promotes long-lasting increases in mice's exploratory tendencies, these increases in exploration do not appear to causally impact general learning abilities.     

The Genetic and Environmental Relationship Between General and Specific Cognitive Abilities in Twins Age 80 and Older

In the first twin study of the old-old, individuals 80 years old and older, we examined the relationship between general and specific cognitive abilities from a genetic perspective. That is, we examined the extent to which genetic and environmental factors influence major group factors of cognitive abilities, independent of general cognitive ability. As part of the OctoTwin project in Sweden, general and specific cognitive abilities were assessed in 52 monozygotic and 65 same-sex dizygotic twin pairs 80 years old and older using a battery of seven tests that assess verbal, spatial, speed-of-processing, and memory performance. Results suggest that genetic effects associated with general cognitive ability ( g ) account for the correlation between g and verbal, spatial, and speed-of-processing abilities. No genetic influences were found for these specific cognitive abilities separate from g . In contrast, memory ability appears to be more distinct genetically from g than are other cognitive abilities. Comparison with younger samples suggests that cognitive abilities relating to speed of processing may be genetically dedifferentiated in the old-old.     

Selling points: What cognitive abilities are tapped by casual video games?

The idea that video games or computer-based applications can improve cognitive function has led to a proliferation of programs claiming to “train the brain.” However, there is often little scientific basis in the development of commercial training programs, and many research-based programs yield inconsistent or weak results. In this study, we sought to better understand the nature of cognitive abilities tapped by casual video games and thus reflect on their potential as a training tool. A moderately large sample of participants (n = 209) played 20 web-based casual games and performed a battery of cognitive tasks. We used cognitive task analysis and multivariate statistical techniques to characterize the relationships between performance metrics. We validated the cognitive abilities measured in the task battery, examined a task analysis-based categorization of the casual games, and then characterized the relationship between game and task performance. We found that games categorized to tap working memory and reasoning were robustly related to performance on working memory and fluid intelligence tasks, with fluid intelligence best predicting scores on working memory and reasoning games. We discuss these results in the context of overlap in cognitive processes engaged by the cognitive tasks and casual games, and within the context of assessing near and far transfer. While this is not a training study, these findings provide a methodology to assess the validity of using certain games as training and assessment devices for specific cognitive abilities, and shed light on the mixed transfer results in the computer-based training literature. Moreover, the results can inform design of a more theoretically-driven and methodologically-sound cognitive training program.     

工作记忆训练及对数学能力的迁移作用

工作记忆缺陷会影响个体数学能力发展。通过记忆策略、广度、刷新、转换等功能的工作记忆训练,可以改善个体认知功能。然而,工作记忆训练对个体的阅读、数学、流体智力等方面的远迁移效果并不一致。研究表明,工作记忆训练可以改善数感、视觉空间能力、推理能力等数学一般技能;也会通过改善语音工作记忆以及空间能力促进数学计算能力,或者通过改善中央执行系统,提升数学问题表征、模式识别、解题迁移、策略选择等复杂的过程,从而促进数学问题解决能力。因此,区分不同数学任务的认知过程,可以获得工作记忆训练对数学能力迁移效果的进一步证据。今后,神经影像学的证据或许也是未来工作记忆训练对数学能力提高的又一佐证。     

工作记忆训练及对数学能力的迁移作用

工作记忆缺陷会影响个体数学能力发展。通过记忆策略、广度、刷新、转换等功能的工作记忆训练,可以改善个体认知功能。然而,工作记忆训练对个体的阅读、数学、流体智力等方面的远迁移效果并不一致。研究表明,工作记忆训练可以改善数感、视觉空间能力、推理能力等数学一般技能;也会通过改善语音工作记忆以及空间能力促进数学计算能力,或者通过改善中央执行系统,提升数学问题表征、模式识别、解题迁移、策略选择等复杂的过程,从而促进数学问题解决能力。因此,区分不同数学任务的认知过程,可以获得工作记忆训练对数学能力迁移效果的进一步证据。今后,神经影像学的证据或许也是未来工作记忆训练对数学能力提高的又一佐证。