Performance Of Working Memory Task Research Articles

When Load is Low, Working Memory is Shielded From Long-Term Memory's Influence.

Previous studies found that episodic long-term memory (eLTM) enhances working memory (WM) performance when both novel and previously learnt word pairs must be retained on a short-term basis. However, there is uncertainty regarding how and when WM draws on eLTM. Three possibilities are (a) that people draw on eLTM only if WM capacity is exceeded; (b) that there is always a contribution of eLTM to WM performance, irrespective of whether prior knowledge is helpful or not; or (c) benefits of prior knowledge are specific to comparisons between conditions which are similarly ambiguous concerning whether LTM may be useful. We built on the assumption that under conditions of a contribution from LTM, these LTM traces of memoranda could benefit or hamper performance in WM tasks depending on the match between the traces stored in LTM and the ones to-be stored in WM in the current trial, yielding proactive facilitation (PF) and proactive interference (PI), respectively. Across four experiments, we familiarized participants with some items before they completed a separate WM task. In accordance with possibility (a) we show that there are indeed conditions in which only WM contributes to performance. Performance deteriorated with the addition of stimuli from eLTM when WM load was low, but not when it was high; and an exchange of information between LTM and WM occurred only when WM capacity was exceeded, with PI and PF effects affecting immediate memory performance in verbal and visual tasks only at higher set sizes.

Causal functional maps of brain rhythms in working memory

Human working memory is a key cognitive process that engages multiple functional anatomical nodes across the brain. Despite a plethora of correlative neuroimaging evidence regarding the working memory architecture, our understanding of critical hubs causally controlling overall performance is incomplete. Causal interpretation requires cognitive testing following safe, temporal, and controllable neuromodulation of specific functional anatomical nodes. Such experiments became available in healthy humans with the advance of transcranial alternating current stimulation (tACS). Here, we synthesize findings of 28 placebo-controlled studies (in total, 1,057 participants) that applied frequency-specific noninvasive stimulation of neural oscillations and examined working memory performance in neurotypical adults. We use a computational meta-modeling method to simulate each intervention in realistic virtual brains and test reported behavioral outcomes against the stimulation-induced electric fields in different brain nodes. Our results show that stimulating anterior frontal and medial temporal theta oscillations and occipitoparietal gamma rhythms leads to significant dose-dependent improvement in working memory task performance. Conversely, prefrontal gamma modulation is detrimental to performance. Moreover, we found distinct spatial expression of theta subbands, where working memory changes followed orbitofrontal high-theta modulation and medial temporal low-theta modulation. Finally, all these results are driven by changes in working memory accuracy rather than processing time measures. These findings provide a fresh view of the working memory mechanisms, complementary to neuroimaging research, and propose hypothesis-driven targets for the clinical treatment of working memory deficits.

Sex dimorphism controls dysbindin-related cognitive dysfunctions in mice and humans with the contribution of COMT.

Cognitive dysfunctions are core-enduring symptoms of schizophrenia, with important sex-related differences. Genetic variants of the DTBPN1 gene associated with reduced dysbindin-1 protein (Dys) expression negatively impact cognitive functions in schizophrenia through a functional epistatic interaction with Catechol-O-methyltransferase (COMT). Dys is involved in the trafficking of dopaminergic receptors, crucial for prefrontal cortex (PFC) signaling regulation. Moreover, dopamine signaling is modulated by estrogens via inhibition of COMT expression. We hypothesized a sex dimorphism in Dys-related cognitive functions dependent on COMT and estrogen levels. Our multidisciplinary approach combined behavioral-molecular findings on genetically modified mice, human postmortem Dys expression data, and in vivo fMRI during a working memory task performance. We found cognitive impairments in male mice related to genetic variants characterized by reduced Dys protein expression (pBonferroni = 0.0001), as well as in male humans through a COMT/Dys functional epistatic interaction involving PFC brain activity during working memory (t(23) = -3.21; pFDR = 0.004). Dorsolateral PFC activity was associated with lower working memory performance in males only (p = 0.04). Also, male humans showed decreased Dys expression in dorsolateral PFC during adulthood (pFDR = 0.05). Female Dys mice showed preserved cognitive performances with deficits only with a lack of estrogen tested in an ovariectomy model (pBonferroni = 0.0001), suggesting that genetic variants reducing Dys protein expression could probably become functional in females when the protective effect of estrogens is attenuated, i.e., during menopause. Overall, our results show the differential impact of functional variants of the DTBPN1 gene interacting with COMT on cognitive functions across sexes in mice and humans, underlying the importance of considering sex as a target for patient stratification and precision medicine in schizophrenia.

Task-irrelevant decorative pictures increase cognitive load during text processing but have no effects on learning or working memory performance: an EEG and eye-tracking study.

Decorative pictures (DP) are often used in multimedia task materials and are commonly considered so-called seductive details as they are commonly not task-relevant. Typically, DP result in mixed effects on behavioral performance measures. The current study focused on the effects of DP on the cognitive load during text reading and working memory task performance. The theta and alpha frequency band power of the electroencephalogram (EEG) and pupil dilation served as proxies of cognitive load. The number of fixations, mean fixation durations, and the number of transitions served as proxies of the attentional focus. For both, text reading and n-back working memory tasks, the presence and congruency of DP were manipulated in four task conditions. DP did neither affect behavioral performance nor subjective ratings of emotional-motivational factors. However, in both tasks, DP increased the cognitive load as revealed by the EEG alpha frequency band power and (at least to some extent) by subjective effort ratings. Notably, the EEG alpha frequency band power was a quite reliable and sensitive proxy of cognitive load. Analyzing the EEG data stimulus-locked and fixation-related, the EEG alpha frequency band power revealed a difference in global and local cognitive load. In sum, the current study underlines the feasibility and use of EEG for multimedia research, especially when combined with eye-tracking.

A preliminary study of dynamic neurochemical changes in the dorsolateral prefrontal cortex during working memory.

Working memory (WM) is one of the fundamental cognitive functions associated with the dorsolateral prefrontal cortex (DLPFC). However, the neurochemical mechanisms of WM, including the dynamic changes in neurometabolites such as glutamate and GABA in the DLPFC, remain unclear. Here, we investigated WM-related glutamate and GABA changes, alongside hemodynamic responses in the DLPFC, using a combination of functional magnetic resonance spectroscopy (fMRS) and functional magnetic resonance imaging (fMRI). During a WM task, we measured Glx (glutamate + glutamine) and GABA levels using GABA editing MEscher-GArwood Point REsolved Spectroscopy (MEGA-PRESS) sequence and blood-oxygen-level-dependent (BOLD) signal changes. In the DLPFC, we observed elevated Glx levels and increased BOLD signal changes during a 2-back task. Specifically, the Glx levels in the DLPFC were significantly higher during the 2-back task compared with fixation, although this difference was not significant when compared with a 0-back task. However, Glx levels during the 0-back task were higher than during fixation. Furthermore, there was a positive correlation between Glx levels in the DLPFC during the 2-back task and the corresponding BOLD signal changes. Notably, higher Glx increases were associated with increased DLPFC activation and lower WM task performance in individuals. No notable changes in DLPFC GABA levels were observed during WM processing. These findings suggest that the modulation of glutamatergic activity in the DLPFC may play a crucial role in both working memory processing and its associated performance outcomes.

Differences in brain activation during working memory tasks between badminton athletes and non-athletes: An fNIRS study

BackgroundWorking memory refers to our ability to temporarily store and process information, and it is crucial for efficient cognition and motor control. In the context of badminton matches, athletes need to make quick decisions and reactions in rapidly changing situations. Athletes with strong working memory capacity can better process this information and translate it into actual motor performance. Although previous research has demonstrated that exercise can improve brain function and structure, it remains unclear how the brain functions of athletes engaged in long-term professional training are specifically involved in performing working memory tasks. MethodIn this study, we assessed behavioral performance and cerebral oxygenation in the prefrontal lobe, using functional near-infrared spectroscopy, with 22 athletes and 30 non-athletes. Each participant was evaluated while performing 1-back, 2-back, and 3-back tasks. The area under the curve (AUC) of HbO (oxyhemoglobin) is used as an indicator of cortical brain oxygenation. ResultsThe behavioral performance results indicated no difference between badminton athletes and non-athletes in the n-back task. We observed significantly different activation in channels of left FPA, right DLPFC, and left VLPFC when performing 3-back tasks. Brain activation indicated that long-term training in badminton caused a better performance in high-load working memory tasks. ConclusionsLong-term professional training in badminton primarily activates the left frontal-parietal attention network (left FPA), right dorsolateral prefrontal cortex (right DLPFC), and left ventrolateral prefrontal cortex (left VLPFC) during working memory tasks.

What is it like to do a visuo-spatial working memory task: A qualitative phenomenological study of the visual span task

Working memory is typically measured with specifically designed psychological tasks. When evaluating the validity of working memory tasks, we commonly focus on the reliability of the outcome measurements. Only rarely do we focus on how participants experience these tasks. Accounting for lived experience of working memory task may help us better understand variability in working memory performance and conscious experience in general. We replicated recently established protocols for the phenomenological investigation of working memory using the visual span task. We collected subjective reports from eighteen healthy participants (10 women) aged 21 to 35 years. We observed that working memory can be phenomenologically characterized at three different time scales: background feelings, strategies, and tactics. On the level of tactics, we identified transmodality (i.e., how one modality of lived experience can be transformed into another one) as the central phenomenological dynamic at play during working memory task performance.

Scaling models of visual working memory to natural images

Over the last few decades, psychologists have developed precise quantitative models of human recall performance in visual working memory (VWM) tasks. However, these models are tailored to a particular class of artificial stimulus displays and simple feature reports from participants (e.g., the color or orientation of a simple object). Our work has two aims. The first is to build models that explain people’s memory errors in continuous report tasks with natural images. Here, we use image generation algorithms to generate continuously varying response alternatives that differ from the stimulus image in natural and complex ways, in order to capture the richness of people’s stored representations. The second aim is to determine whether models that do a good job of explaining memory errors with natural images also explain errors in the more heavily studied domain of artificial displays with simple items. We find that: (i) features taken from state-of-the-art deep encoders predict trial-level difficulty in natural images better than several reasonable baselines; and (ii) the same visual encoders can reproduce set-size effects and response bias curves in the artificial stimulus domains of orientation and color. Moving forward, our approach offers a scalable way to build a more generalized understanding of VWM representations by combining recent advances in both AI and cognitive modeling.

Theta-Alpha Connectivity in the Hippocampal-Entorhinal Circuit Predicts Working Memory Load.

Working memory (WM) maintenance relies on multiple brain regions and inter-regional communications. The hippocampus and entorhinal cortex (EC) are thought to support this operation. Besides, EC is the main gateway for information between the hippocampus and neocortex. However, the circuit-level mechanism of this interaction during WM maintenance remains unclear in humans. To address these questions, we recorded the intracranial electroencephalography from the hippocampus and EC while patients (N = 13, six females) performed WM tasks. We found that WM maintenance was accompanied by enhanced theta/alpha band (2-12 Hz) phase synchronization between the hippocampus to the EC. The Granger causality and phase slope index analyses consistently showed that WM maintenance was associated with theta/alpha band-coordinated unidirectional influence from the hippocampus to the EC. Besides, this unidirectional inter-regional communication increased with WM load and predicted WM load during memory maintenance. These findings demonstrate that WM maintenance in humans engages the hippocampal-entorhinal circuit, with the hippocampus influencing the EC in a load-dependent manner.

Working Memory Ability Evaluation Based on Fuzzy Support Vector Regression.

One's working memory process is a fundamental cognitive activity which often serves as an indicator of brain disease and cognitive impairment. In this research, the approach to evaluate working memory ability by means of electroencephalography (EEG) analysis was proposed. The result shows that the EEG signals of subjects share some characteristics when performing working memory tasks. Through correlation analysis, a working memory model describes the changes in EEG signals within alpha, beta and gamma waves, which shows an inverse tendency compared to Zen meditation. The working memory ability of subjects can be predicted using multi-linear support vector regression (SVR) with fuzzy C-mean (FCM) clustering and knowledge-based fuzzy support vector regression (FSVR), which reaches the mean square error of 0.6 in our collected data. The latter, designed based on the working memory model, achieves the best performance. The research provides the insight of the working memory process from the EEG aspect to become an example of cognitive function analysis and prediction.

Spontaneous emotional regulation under experimental emotional condition: The role of working memory.

The present research studied the bidirectional effects of working memory (WM) capacity and emotional regulation; that is, the effect of WM capacity on spontaneous emotional regulation and whether the emotional valence to be regulated has a differential impact on performance in a second WM task. Participants (79) first completed a WM span task (Digit Span), then a self-report emotional intelligence task, which was followed by randomly assigned mock Positive-feedback, Negative-feedback, or No-feedback. In the Negative-feedback and Positive-feedback conditions, a dummy report based on participants' responses to the Trait Meta Mood- 21 was shown on the screen. After that, participants completed another WM task (Running Span). An ordinary least squares multiple linear regression was used to evaluate the predictive power of WM span and experimental condition on post-feedback test performance. The model yielded a significant effect on post-feedback test performance for Negative-feedback and a marginal significant effect for the interaction of this parameter with WM span. The results showed that participants in the Negative-feedback condition performed worse than those assigned to other conditions, and individuals with a higher WM capacity were less susceptible to negative experimental stimuli.

Differences in Brain Functional Network Topology in High and Low Working Memory Performance

Nowadays the network approach in neuroscience provides a promising way of analyzing neurophysiological mechanisms that underlie psychological functions and is widely used to study working memory. To date, data obtained in neuroimaging studies links working memory with topological features of brain networks, such as increased connectivity between frontal, parietal, and temporal regions, as well as increased integration in brain networks as a whole. The present study examines the relationship between the topological characteristics of functional brain networks with the performance in the Sternberg item recognition paradigm based on electroencephalographic data. It is shown that the higher performance in Sternberg paradigm, implying a higher efficiency of the processes of encoding, storage, and retrieval of information from working memory, is associated with an increase in the integration of functional networks, expressed in differences in the clustering coefficient, participation coefficient, Wiener index and eigenvector centrality between the groups of high and low working memory task performance (p < .01). In addition, our data suggest the variability in the topological pattern of connectivity, which can be traced through changes in the magnitude of the standard deviation of the values of topological metrics during the task.

Aberrant oscillatory activity in neurofibromatosis type 1: an EEG study of resting state and working memory

BackgroundNeurofibromatosis type 1 (NF1) is a genetic neurodevelopmental disorder commonly associated with impaired cognitive function. Despite the well-explored functional roles of neural oscillations in neurotypical populations, only a limited number of studies have investigated oscillatory activity in the NF1 population.MethodsWe compared oscillatory spectral power and theta phase coherence in a paediatric sample with NF1 (N = 16; mean age: 13.03 years; female: n = 7) to an age/sex-matched typically developing control group (N = 16; mean age: 13.34 years; female: n = 7) using electroencephalography measured during rest and during working memory task performance.ResultsRelative to typically developing children, the NF1 group displayed higher resting state slow wave power and a lower peak alpha frequency. Moreover, higher theta power and frontoparietal theta phase coherence were observed in the NF1 group during working memory task performance, but these differences disappeared when controlling for baseline (resting state) activity.ConclusionsOverall, results suggest that NF1 is characterised by aberrant resting state oscillatory activity that may contribute towards the cognitive impairments experienced in this population.Trial registrationClinicalTrials.gov, NCT03310996 (first posted: October 16, 2017).

Influence of noninvasive brain stimulation on connectivity and local activation: a combined tDCS and fMRI study

The effect of transcranial direct current stimulation (tDCS) on neurobiological mechanisms underlying executive function in the human brain remains elusive. This study aims at examining the effect of anodal and cathodal tDCS over the left dorsolateral prefrontal cortex (DLPFC) in comparison with sham stimulation on resting-state connectivity as well as functional activation and working memory performance. We hypothesized perturbed fronto-parietal resting-state connectivity during stimulation and altered working memory performance combined with modified functional working memory-related activation. We applied tDCS with 1 mA for 21 min over the DLPFC inside an fMRI scanner. During stimulation, resting-state fMRI was acquired and task-dependent fMRI during working memory task performance was acquired directly after stimulation. N = 36 healthy subjects were studied in a within-subject design with three different experimental conditions (anodal, cathodal and sham) in a double-blind design. Seed-based functional connectivity analyses and dynamic causal modeling were conducted for the resting-state fMRI data. We found a significant stimulation by region interaction in the seed-based ROI-to-ROI resting-state connectivity, but no effect on effective connectivity. We also did not find an effect of stimulation on task-dependent signal alterations in working memory activation in our regions of interest and no effect on working memory performance parameters. We found effects on measures of seed-based resting-state connectivity, while measures of effective connectivity and task-based connectivity did not show any stimulation effect. We could not replicate previous findings of tDCS stimulation effects on behavioral outcomes. We critically discuss possible methodological limitations and implications for future studies.

Individual prefrontal neurons contribute to sensory-to-motor information transformation by rotating reference frames during spatial working memory performance.

Performing working memory tasks correctly requires not only the temporary maintenance of information but also the visual-to-motor transformation of information. Although sustained delay-period activity is known to be a mechanism for temporarily maintaining information, the mechanism for information transformation is not well known. An analysis using a population of delay-period activities recorded from prefrontal neurons visualized a gradual change of maintained information from sensory to motor as the delay period progressed. However, the contributions of individual prefrontal neurons to this process are not known. In the present study, we used a version of the delayed-response task, in which monkeys needed to make a saccade 90o clockwise from a visual cue after a 3-s delay, and examined the temporal change in the preferred directions of delay-period activity during the delay period for individual neurons. One group of prefrontal neurons encoded the cue direction by a retinotopic reference frame and either maintained it throughout the delay period or rotated it 90o counterclockwise to adjust visual information to saccade information, whereas other groups of neurons encoded the cue direction by a saccade-based reference frame and rotated it 90o clockwise. The results indicate that visual-to-motor information transformation is achieved by manipulating the reference frame to adjust visual coordinates to motor coordinates.

Effortfulness of visual working memory: Gauged by physical exertion.

Active maintenance of information in working memory (WM) is an essential but effortful cognitive process. Yet, the effortful nature of WM remains poorly understood. Here, we constructed a model to evaluate how perceived effort of WM is directly compared to that of physical exertion. In Experiment 1, participants freely chose to either remember a certain number of colors in a visual WM task or hold a hand dynamometer to a required percentage of maximal voluntary contraction (%MVC) to obtain a fixed task credit upon successful task completion. We found that participants discounted WM-related effort in the same way as they discounted handgrip-related effort based on a computation of expected choice outcomes (hence utility) associated with different task loads. This rationality in an observer's prospective choice in Experiment 1 was generalized to retrospective choice in Experiment 2 where participants reported which task was more effortful immediately after they had performed both tasks in a randomized order without any reward or feedback. Experiment 3 further probed this shared mechanism using a dual-task paradigm. As predicted by our model, we found that physical exertion could disrupt the performance in the concurrent WM task, proportional to the iso-effort relationship between WM and physical exertion when task loads were high for both tasks. Collectively, our findings converge on a shared computational principle connecting task load, perceived effort, and choice utility across physical and cognitive domains. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Visual mental imagery and verbal working memory: evidence from consecutive interpreting

ABSTRACT The link between the different types and components of mental imagery and efficiency in tasks involving memory storage and processing is not clear. The direction of the effect (facilitation/deterioration) usually depends on the task in question and the cognitive processes involved. Here, we investigate the possible contribution of visual and auditory imagery components to performance in a verbal working memory task (i.e. consecutive interpreting) in which accuracy is not dependent on mental imagery yet with high individual variability due to exacting memory and cognitive control demands. The mental imagery of 38 translation-interpreting undergraduates was measured on four self-reported scales with the vividness, control, and preference components and with a mental rotation test. Participants were then asked to consecutively interpret 10 speeches from English into Turkish. Mixed-effects models revealed that only control of visual mental imagery measured with Gordon’s Test of Visual Imagery Control predicts verbal transfer accuracy in consecutive interpreting.

Autistic traits are associated with enhanced working memory capacity for abstract visual stimuli

We tested whether the association between autistic traits and enhanced performance in visual-perceptual tasks extends to visual working memory capacity. We predicted that any positive effect of autistic traits on visual working memory performance would be greatest during domain-specific tasks, in which visual resources must be relied upon. We used a visual ‘matrix’ task, involving recall of black-and-white chequered patterns which increased in size, to establish participants' capacity (span). We assessed 144 young adults' (M = 22.0 years, SD = 2.5) performance on abstract, ‘low semantic’ versus ‘high semantic’ task versions. The latter offered multimodal coding due to the availability of long-term memory resources that could supplement visual working memory. Participants also completed measures of autistic traits and trait anxiety. Autistic traits, especially Attention to Detail, Attention Switching, and Communication, positively predicted visual working memory capacity, specifically in the low semantic task, which relies on visual working memory resources. Autistic traits are therefore associated with enhanced processing and recall of visual information. The benefit is removed, however, when multimodal coding may be incorporated, emphasising the visual nature of the benefit. Strengths in focused attention to detail therefore appear to benefit domain-specific visual working memory task performance.

Prefrontal oxygenation and working memory in patients with type 2 diabetes mellitus following integrated yoga: a randomized controlled trial.

Type 2 diabetes mellitus (T2DM) alters brain functional and structural connectivity leading to cognitive dysfunction. This study examined the effect of a 12-week yoga intervention on prefrontal cortex (PFC) oxygenation and working memory in patients with T2DM. Fifty participants were randomized into yoga and waitlist control groups. The yoga protocol specific to T2DM was followed. The pre- (day 1), mid- (6weeks) and post-intervention (12weeks) assessments included measurement of PFC oxygenation while performing working memory tasks (n-back) using functional near-infrared spectroscopy. Following a 12-week intervention, the yoga group showed improved performance in working memory [accuracy (geometric mean difference of 3.15%, 95% CI [2.33,3.96], p = 0.001) and reaction time (mean difference of 100.8 milliseconds,95% CI [- 166.6, - 35.1], p = 0.002] in the high task load (2-back) associated with higher oxygenation in dorsolateral PFC (β coefficient mean difference of 95.6, 95% CI [0.23,191], p = 0.049) and ventrolateral PFC (β coefficient mean difference of 53.4, 95% CI [7.8,98.9], p = 0.018) regions. Higher oxygenation in dorsolateral PFC during 2-back task was positively correlated with accuracy (r(23) = 0.65, p < 0.001) and negatively correlated with reaction time (r(23) = - 0.47,p = 0.017). Integrated yoga practice may improve working memory performance associated with higher PFC oxygenation in patients with T2DM. As 12weeks of yoga intervention improved working memory performance, the regular practice of yoga may have the potential to prevent decline of cognitive functions in clinical conditions.

Pausing and reorienting behaviors enhance the performance of a spatial working memory task

During spatial working memory tasks, animals need to retain information about a previous trial in order to successfully select their next trajectory. Specifically, the delayed non-match to position task requires rats to follow a cued sample trajectory, then select the opposite route after a delay period. When faced with this choice, rats will occasionally exhibit complex behaviors, such as pausing and sweeping their head back and forth. These behaviors, called vicarious trial and error (VTE), are thought to be a behavioral manifestation of deliberation. However, we identified similarly complex behaviors during sample-phase traversals, despite the fact that these laps do not require a decision. First, we identified that these behaviors occurred more often after incorrect trials than before them, indicating that rats are retaining information between trials. Next, we determined that these pause-and-reorient (PAR) behaviors increased the likelihood of the next choice being selected correctly, suggesting that these behaviors assist the rat in successful task performance. Finally, we identified similarities between PARs and choice-phase VTEs, suggesting that VTEs may not only be reflective of deliberation, but may also contribute to a strategy for successful performance of spatial working memory tasks.