Differential effects of differing intensities of acute exercise on speed and accuracy of cognition: A meta-analytical investigation

The primary purpose of this study was to examine, using meta-analytical techniques, the differential effects of differing intensities of acute exercise on speed and accuracy of cognition. Overall, exercise demonstrated a small, significant mean effect size (g = 0.14, p < 0.01) on cognition. Examination of the comparison between speed and accuracy dependent variables showed that speed accounted for most of the effect. For speed, moderate intensity exercise demonstrated a significantly larger mean effect size than those for low and high intensities. For speed of processing during moderate intensity exercise, central executive tasks showed a larger effect size than recall and alertness/attention tasks; and mean effect size for counterbalanced or randomized studies was significantly greater than for studies in which a pre-exercise followed by during or post-exercise protocol was used. There was no significant difference between mean effect sizes when testing took place post-exercise compared to during exercise for speed but accuracy studies demonstrated a significantly larger mean effect size post-exercise. It was concluded that increased arousal during moderate intensity exercise resulted in faster speed of processing. The very limited effect on accuracy may be due to the failure to choose tests which are complex enough to measure exercise-induced changes in accuracy of performance.     

Neuroanatomical correlates of processing in visual and visuospatial working memory

Working memory is traditionally seen as being organised in a modular way with a central executive orchestrating at least two slave systems (phonological loop and visuospatial sketch pad). Neuroanatomical correlates of the visual and visuospatial subsystems and the central executive are discussed in this article. A series of experiments are presented yielding evidence for a differentiation into active and passive processing in working memory as well as their neuroanatomical correlates in the prefrontal cortex. Data, yielding evidence for an interaction and separation of visual and visuospatial working memory are presented and discussed. Further results are presented which suggest a convergence of these two systems with increasing working memory demands. The discussed findings will give new insight in the organisation of visual and visuospatial working memory on the anatomical level.     

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.     

不同强度短时有氧运动对执行功能的影响

探讨短时有氧运动对执行功能的影响是否与运动强度和性别有关, 为从运动强度和性别角度选择合理的有氧运动干预方案改善执行功能提供基础。研究采用混合设计, 选取30名大学生(男女人数各半), 使用功率自行车实施30分钟的不同强度有氧运动, 使用Flanker任务、2-back任务和数字More-odd shifting任务分别测查被试基线、小强度短时有氧运动、中强度短时有氧运动和大强度短时有氧运动后执行功能的抑制、刷新和转换三个子功能的变化, 结果表明：不同强度的短时有氧运动对执行功能产生选择性的积极影响, 且不随性别变化而改变。     

Using TD learning to simulate working memory performance in a model of the prefrontal cortex and basal ganglia

Delayed-response tasks (DRTs) have been used to assess working memory (WM) processes in human and nonhuman animals. Experiments have shown that the basal ganglia (BG) and dorsolateral prefrontal cortex (DLPFC) subserve DRT performance. Here, we report the results of simulation studies of a systems-level model of DRT performance. The model was trained using the temporal difference (TD) algorithm and uses an actor-critic architecture. The matrisomes of the BG represent the actor and the striosomes represent the critic. Unlike existing models, we hypothesize that the BG subserve the selection of both motor- and cognitive-related information in these tasks. We also assume that the learning of both processes is based on reward presentation. A novel feature of the model is the incorporation of delay-active neurons in the matrisomes, in addition to DLPFC. Another novel feature of the model is the subdivision of the matrisomal neurons into segregated winner-take-all (WTA) networks consisting of delay- versus transiently-active units.Our simulation model proposes a new neural mechanism to account for the occurrence of perseverative responses in WM tasks in striatal-, as well as in prefrontal damaged subjects. Simulation results also show that the model both accounts for the phenomenon of time shifting of dopamine phasic signals and the effects of partial reinforcement and reward magnitude on WM performance at both behavioral and neural levels. Our simulation results also found that the TD algorithm can subserve learning in delayed-reversal tasks.     

The effects of acute resistance exercise on young and older males' working memory

ObjectivesThe aim of the current study was two-fold: to examine the effects of acute, moderate intensity resistance exercise (RE) on working memory in young and older males, respectively.DesignA two-study approach with a within-subjects design.MethodsStudy 1 recruited 20 young males aged 21–30 years. Participants underwent two experimental sessions, the exercise session and reading session, in a counterbalanced order. The RE protocol included two sets of 10 repetitions at 70% of 10-repetition maximum of eight muscle exercises. The Sternberg working memory paradigm with two probe types (in-set probes and out-of-set probes) was used as the cognitive task where reaction times (RT) and response accuracy were identified. Study 2 recruited 20 older male adults aged 65–72 years. The methods and experimental procedures were the same as Study 1.ResultsIn Study 1, young males demonstrated shorter RTs after the exercise treatment as compared with the reading treatment for both probe types. In Study 2, older males showed shorter RTs after the exercise treatment as compared with the reading treatment in the out-of-set probes only.ConclusionsWhile acute RE benefited working memory in both young and older males, rather than general facilitation, it was shown to have a disproportionately larger effect on older males for tasks involving higher working memory demands.     

Systemic and local administration of estradiol into the prefrontal cortex or hippocampus differentially alters working memory

The influence of estradiol on learning and memory is dependent on a number of factors. The effects of physiological levels of estradiol on the acquisition of a spatial working memory task mediated by the prefrontal cortex (PFC) and the hippocampus were examined in Experiment 1. Ovariectomized Long-Evans rats received daily injections of estradiol or vehicle were tested on the win-shift version of the radial arm maze. A high dose of estradiol benzoate (5 microg) enhanced acquisition of the task, whereas a low dose of estradiol (0.3 microg) increased the number of errors committed over 17 days of testing. Experiment 2 was conducted to examine site-specific influences of estradiol on spatial working memory in well-trained rats. Saline and estradiol cyclodextrin (0.1 and 0.9 microg) were infused into the prelimbic region of the PFC or dorsal hippocampus 40 min prior to testing on the win-shift task. Infusions of estradiol into both brain areas attenuated saline-infusion disruptions in working memory. Specifically, the higher dose of estradiol facilitated working memory when infused into the PFC, whereas the lower dose of estradiol facilitated performance when infused into the dorsal hippocampus. Moreover, working memory was significantly impaired 24 h after infusions of estradiol into the dorsal hippocampus but not the PFC. These data provide further evidence for the notion that estradiol can dose-dependently alter memory processes and suggest that facilitation or disruptions of working memory by estradiol are site- and time-specific.     

Differential effects of scopolamine and lorazepam on working memory maintenance versus manipulation processes

Between-study comparisons of benzodiazepine and anticholinergic drugs on working memory suggest that anticholinergics may produce greater impairment in maintenance processes, whereas benzodiazepines may produce greater impairment in manipulation processes. This study directly compared acute effects of the benzodiazepine lorazepam (1.0 and 2.0 mg/70 kg, orally administered) and the anticholinergic scopolamine (0.25 and 0.50 mg/ 70 kg, subcutaneously administered) on working memory maintenance (storage and rehearsal) and manipulation processes in a placebo-controlled, double-dummy, double-blind, crossover design in 20 healthy volunteers. Using a modified Sternberg paradigm, storage, rehearsal, and manipulation processes were parametrically manipulated by varying memory load, delay between stimulus presentation and test, and number of operations performed on the letter strings, respectively, while controlling for drug effects on nonmemory processes. As predicted, the results suggested greater impairment in maintenance processes (rehearsal) with scopolamine than with lorazepam and greater impairment in manipulation processes with lorazepam than with scopolamine. In addition, the results suggested greater overall slowing of working memory processes with lorazepam.     

Cross‐sectional study on the relationship between music training and working memory in adults

Learning to play musical instruments has been shown to enhance a wide variety of cognitive domains. The present study investigated the specific aspects of working memory (WM) that differed between adult musicians and non‐musicians. Twenty‐four musicians and 30 non‐musicians matched for age, gender, years of formal education, and verbal intelligence performed several WM tasks. A multivariate analysis of covariance, wherein family income was controlled, revealed that musicians outperformed non‐musicians in tasks related to visual–motor coordination, visual scanning ability, visual processing speed, and spatial memory. However, no significant differences were found in phonological and visual memory capacity. This study supports the view that music training is associated to specific (and not general) WM skills.     

The effects of autobiographical memory and visual perspective on working memory

The present research aims to explore whether recalling and writing about autobiographical memory from different perspectives (first-person perspective vs. third-person perspective) could affect cognitive function. The participants first performed a working memory task to evaluate their working memory capacity as a baseline and then were instructed to recall (Study 1) or write about (Study 2) personal events (failures vs. successes) from the first-person perspective or the third-person perspective. Finally, they performed the working memory task again. The results suggested that autobiographical memory and perspective influence working memory interactively. When recalling a success, the participants who recalled from the third-person perspective performed better than those who recalled from the first-person perspective on the working memory capacity task; when recalling a failure, the opposite was true.     

The feasibility and acceptability of assessing inhibitory control and working memory among adolescents via an ecological momentary assessment approach

Early adolescence is a critical period for the development of executive function (EF). EF deficits are associated with increased engagement in multiple health risk behaviors and may be influenced by momentary factors, such as state mindfulness and physical activity. Ecological momentary assessment (EMA) leverages the increasing ubiquity of smart-phones to assess moment-to-moment changes in neurocognition and behavior with minimal recall bias and high ecological validity. As such, EMA is a promising method for delivering performance-based EF tasks and assessing the degree to which EF is influenced by momentary variation in its putative antecedents (e.g. state mindfulness and PA). This study adapts the (1) State Mindfulness Attention Awareness Scale, (2) physical activity/sedentary behavior recall items, (3) complex symmetry span working memory task, and (4) the child flanker inhibitory control task into an EMA tool delivered via iPhone using Inquisit Web. This tool was piloted with a sample of 32 seventh graders over a 72 h period. Participants’ posttest survey responses indicated that they found these study activities to be enjoyable, non-burdensome, not overly difficult, and preferable to pencil-and-paper instruments. Baseline correlations between flanker task performance and both BRIEF inhibitory control (σ = .23) and working memory subscales (σ = .34) were moderate. Correlations between symmetry span working memory task performance and BRIEF inhibitory control (σabsolute = .28; σpartial = .16) and working memory subscales (σabsolute = .19; σpartial = .15) were slightly lower, demonstrating associations consistent with previous studies. This study supports the feasibility and acceptability of administering two common performance-based EF tasks to adolescents via an EMA approach.     

Executive functioning by 18‐24‐month‐old children: effects of inhibition,working memory demands and narrative in a novel detour‐reaching task

Infants can inhibit a prepotent but wrong action towards a goal in order to perform a causal means‐action. It is not clear, however, whether infants can perform an arbitrary means‐action while inhibiting a prepotent response. In four experiments, we explore this executive functioning in 18–24‐month‐old children. The working memory and inhibition demands in a novel means‐end problem were systematically varied in terms of the type and combination of means‐action(s) (causal or arbitrary) contained within the task, the number of means‐actions (1 or 2), the goal visual availability and whether the task was accompanied by a narrative. Experiments 1 and 2 showed that children performed tasks that contained causal as opposed to arbitrary information more accurately; accuracy was also higher in tasks containing only one step. Experiment 2 also demonstrated that performance in the arbitrary task improved significantly when all sources of prepotency were removed. In Experiment 3, task performance improved when the two means‐actions were intelligibly linked to the task goal. Experiment 4 demonstrated that the use of a narrative that provided a meaningful (non‐causal) link between the two means‐actions also improved children's performance by assisting their working memory in the generation of a rationale. Findings provide an initial account of executive functioning in the months that bring the end of infancy. Copyright © 2006 John Wiley & Sons, Ltd.     

Identifying the nature of impairments in executive functioning and working memory of children with severe difficulties in arithmetic

An age-matched achievement-matched design was used to examine whether the executive functioning and working memory impairments exhibited by children with severe difficulties in arithmetic (SDA) are better viewed as developmental lags or as cognitive deficits. Three groups of children were included: 20 SDA children, 20 typically achieving children (CM) matched in chronological age with the SDA children, and 20 younger typically achieving children (AM) matched in achievement with the SDA group. While children with SDA did not exhibit impairments in color-word inhibition and verbal working memory, they did demonstrate impairments in shifting, quantity-digits inhibition, and visuospatial working memory. As children with SDA did not perform more poorly than their AM counterparts on any of these tasks, impairments in specific areas of executive functioning and working memory appear to reflect developmental lags rather than cognitive deficits.     

Written expression in boys with ADHD: The mediating roles of working memory and oral expression

The written expression difficulties experienced by children with ADHD are widely recognized; however, scant empirical evidence exists concerning the cognitive mechanisms and processes underlying these deficiencies. The current study investigated the independent and potentially interactive contributions of two developmentally antecedent cognitive processes – viz., working memory (WM) and oral expression – hypothesized to influence written expression ability in boys. Thirty-three boys with ADHD-Combined Presentation and 27 neurotypical (NT) boys 8–12 years of age were administered standardized measures of oral and written expression, and multiple counterbalanced tasks to assess WM central executive (CE) processes, WM phonological short-term memory (PH STM), and WM visuospatial short-term memory (VS STM). Bias-corrected bootstrapped mediation analyses revealed a significant mediation effect, wherein the independent and interactive effects of PH STM and oral expression collectively explained 76% of the diagnostic status to written expression relation. The implications of the obtained results for clinical practice suggest that children with ADHD may benefit by incorporating a blended approach that simultaneously strengthens PH STM capacity and oral expression abilities as antecedents to engaging in writing-related activities.     

The extent of working memory deficits associated with Williams syndrome: exploration of verbal and spatial domains and executively controlled processes

The present study investigated verbal and spatial working memory (WM) functioning in individuals with the neuro-developmental disorder Williams syndrome (WS) using WM component tasks. While there is strong evidence of WM impairments in WS, previous research has focused on short-term memory and has neglected assessment of executive components of WM. There is a particular lack of consensus concerning the profile of verbal WM functioning in WS. Here, WS participants were compared to typically developing participants matched for (1) verbal ability and (2) spatial ability (N = 14 in each of the 3 groups). Individuals with WS were impaired on verbal WM tasks, both those involving short-term maintenance of information and executive manipulation, in comparison to verbal-matched controls. Surprisingly, individuals with WS were not impaired on a spatial task assessing short-term maintenance of information in memory (remembering spatial locations) compared to spatial-matched controls. They were, however, impaired on a spatial executive WM task requiring the manipulation of spatial information in memory. The present study suggests that individuals with WS show WM impairments that extend to both verbal and spatial domains, although spatial deficits are selective to executive aspects of WM function.     

Fathers' views of the effects on their families of children with Down syndrome

This study examined fathers' views about the effects of children with Down syndrome on themselves and their families. Taped interviews were obtained from 90 fathers of children aged from 7 to 14 years. Qualitative analysis of the interview data revealed 28 categories of comments made by fathers. The most frequent comment, made by 46% of fathers, was about the cheerful personality of their child with Down syndrome. About 42% of fathers talked about the initial trauma they experienced following the diagnosis; 43% of them bemoaned the restrictions imposed on the family, and 30% commented that the child had minimal effects on family life. The greatest concern expressed by fathers was the long-term provision for their children. More fathers commented on the positive effects on their marriage than on negative effects. The results of this study provide a somewhat different view of fathers' experiences to that found in the existing literature.     

Differential constraints on the working memory and reading abilities of individuals with learning difficulties and typically developing children

This study examined the factors that constrain the working memory span performance and reading ability of individuals with generalized learning difficulties. In the study, 50 individuals with learning difficulties (LD) and 50 typically developing children (TD) matched for reading age completed two working memory span tasks. Participants also completed independent measures of the processing and storage operations involved in each working memory span task and Raven's Coloured Progressive Matrices. The results showed that despite an equivalent level of working memory span, the relative importance of the constraints on working memory differed between the groups. In addition, working memory span was not closely related to word recognition or sentence comprehension performance in the LD group. These results suggest that the working memory span performance of LD and TD individuals may reflect different working memory limitations and that individuals with generalized learning difficulties may approach cognitive tasks in a qualitatively different way from that of typically developing individuals.     

Working memory improvement with non-invasive brain stimulation of the dorsolateral prefrontal cortex: A systematic review and meta-analysis

Recent studies have used non-invasive brain stimulation (NIBS) techniques, such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), to increase dorsolateral prefrontal cortex (DLPFC) activity and, consequently, working memory (WM) performance. However, such experiments have yielded mixed results, possibly due to small sample sizes and heterogeneity of outcomes. Therefore, our aim was to perform a systematic review and meta-analyses on NIBS studies assessing the n-back task, which is a reliable index for WM. From the first data available to February 2013, we looked for sham-controlled, randomized studies that used NIBS over the DLPFC using the n-back task in PubMed/MEDLINE and other databases. Twelve studies (describing 33 experiments) matched our eligibility criteria. Active vs. sham NIBS was significantly associated with faster response times (RTs), higher percentage of correct responses and lower percentage of error responses. However, meta-regressions showed that tDCS (vs. rTMS) presented only an improvement in RT, and not in accuracy. This could have occurred in part because almost all tDCS studies employed a crossover design, possibly due to the reliable tDCS blinding. Study design was also associated with no improvement in correct responses in the active vs. sham groups. To conclude, rTMS of the DLPFC significantly improved all measures of WM performance whereas tDCS significantly improved RT, but not the percentage of correct and error responses. Mechanistic insights on the role of DLPFC in WM are further discussed, as well as how NIBS techniques could be used in neuropsychiatric samples presenting WM deficits, such as major depression, dementia and schizophrenia.     

Strategic and automatic effects of visual working memory on attention in visual search

Previous research indicates that visual attention can be automatically captured by sensory inputs that match the contents of visual working memory. However, Woodman and Luck (2007) showed that information in working memory can be used flexibly as a template for either selection or rejection according to task demands. We report two experiments that extend their work. Participants performed a visual search task while maintaining items in visual working memory. Memory items were presented for either a short or long exposure duration immediately prior to the search task. Memory was tested by a change-detection task immediately afterwards. On a random half of trials items in memory matched either one distractor in the search task (Experiment 1) or three (Experiment 2). The main result was that matching distractors speeded or slowed target detection depending on whether memory items were presented for a long or short duration. These effects were more in evidence with three matching distractors than one. We conclude that the influence of visual working memory on visual search is indeed flexible but is not solely a function of task demands. Our results suggest that attentional capture by perceptual inputs matching information in visual working memory involves a fast automatic process that can be overridden by a slower top-down process of attentional avoidance.     

The effects of categorical similarity and feature-space proximity on visual working memory processing

Two patterns of data predict that similarity has a positive effect and a negative effect on visual working memory (VWM) processing. We assume that these two empirical outcomes do not distinguish categorical similarity from feature-space proximity, resulting in this divergence. To investigate how categorical similarity and feature-space proximity modulate VWM, we tested memory for an array of pictures drawn from either mixed categories or a single category in which feature-space proximity varied along a morph continuum in a change-detection task. We found that memory under the mixed-category condition was better than that under the single-category condition, whereas memory under high feature-space proximity was superior to that under low feature-space proximity. These patterns were unaffected by manipulations of stimulus type (faces or scenes), encoding duration (limited or self-paced), and presentation format (simultaneous or sequential). These results are consistent with our hypotheses that categorical similarity inhibits VWM, whereas feature-space proximity facilitates VWM. We also found that memory for items with low feature-space proximity benefited more from mixed-category encoding than that for items with high feature-space proximity. Memory for faces benefited more from mixed-category encoding than scenes, whereas memory for scenes benefited more from feature-space proximity than faces. These results suggest that centre-surround inhibition organization might underlie similarity effects in VWM. Centre-surround inhibition organization for complex real-world objects could have both categorical level and feature-space level. The feature-space level might differ by category.