N-back Research Articles

Evidence for separate backward recall and n-back working memory factors: a large-scale latent variable analysis

ABSTRACT Multiple studies have explored the factor structure of working memory (WM) tasks, yet few have done so controlling for both the domain and category of the memory items in a single study. In the current pre-registered study, we conducted a large-scale latent variable analysis using variant forms of n-back and backward recall tasks to test whether they measured a single underlying construct, or were distinguished by stimuli-, domain-, or paradigm-specific factors. Exploratory analyses investigated how the resulting WM factor(s) were linked to fluid intelligence. Participants (N = 703) completed a fluid reasoning test and multiple n-back and backward recall tasks containing memoranda that varied across (spatial or verbal material) and within (verbal digits or letters) domain, allowing the variance specific to task content and paradigm to be assessed. Two distinct but related backward recall and n-back constructs best captured the data, in comparison to other plausible model constructions (single WM factor, two-factor domain, and three-factor materials models). Common variance associated with WM was a stronger predictor of fluid reasoning than a residual n-back factor, but the backward recall factor predicted fluid reasoning as strongly as the common WM factor. These data emphasise the distinctiveness between backward recall and n-back tasks.

Empirical examination of working memory performance and its neural correlates in relation to delay discounting in two large samples

The neurobiological basis of working memory and delay discounting are theorized to overlap, but few studies have empirically examined these relations in large samples. To address this, we investigated the association of neural activation during an fMRI N-Back working memory task with delay discounting area, as well as in- and out-of-scanner working memory measures. These analyses were conducted in two large task fMRI datasets, the Human Connectome Project and the Adolescent Brain Cognitive Development Study. Although in- and out-of-scanner working memory performance were significantly associated with N-back task brain activation regions, contrary to our hypotheses, there were no significant associations between working memory task activation and delay discounting scores. These findings call into question the extent of the neural overlap in delay discounting and working memory and highlight the need for more investigations directly interrogating overlapping and distinct brain regions across cognitive neuroscience tasks.

A Multimodal Magnetic Resonance Imaging Study on Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Feasibility and Clinical Correlation.

Background/Objectives: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a neurological disorder characterized by post-exertional malaise. Despite its clinical relevance, the disease mechanisms of ME/CFS are not fully understood. The previous studies targeting brain function or metabolites have been inconclusive in understanding ME/CFS complexity. We combined single-voxel magnetic resonance spectroscopy (SV-MRS) and functional magnetic resonance imaging (fMRI). Our objectives were to examine the feasibility of the multimodal MRI protocol, identify possible differences between ME/CFS and healthy controls (HCs), and relate MRI findings with clinical symptoms. Methods: We enrolled 18 female ME/CFS participants (mean age: 39.7 ± 12.0 years) and five HCs (mean age: 45.6 ± 14.5 years). SV-MRS spectra were acquired from three voxels of interest: the anterior cingulate gyrus (ACC), brainstem (BS), and left dorsolateral prefrontal cortex (L-DLPFC). Whole-brain fMRI used n-back task testing working memory and executive function. The feasibility was assessed as protocol completion rate and time. Group differences in brain metabolites and fMRI activation between ME/CFS and HCs were compared and correlated with behavioral and symptom severity measurements. Results: The completion rate was 100% regardless of participant group without causing immediate fatigue. ME/CFS appeared to show a higher N-Acetylaspartate in L-DLPFC compared to HCs (OR = 8.49, p = 0.040), correlating with poorer fatigue, pain, and sleep quality scores (p's = 0.001-0.015). An increase in brain activation involving the frontal lobe and the brainstem was observed in ME/CFS compared to HCs (Z > 3.4, p's < 0.010). Conclusions: The study demonstrates the feasibility of combining MRS and fMRI to capture neurochemical and neurophysiological features of ME/CFS in female participants. Further research with larger cohorts of more representative sampling and follow-ups is needed to validate these apparent differences between ME/CFS and HCs.

Designing Novel Physiologic Monitor Displays for Combat Medics.

Combat medics who are responsible for the care of injured warfighters face challenges from their reliance on medical alarms that exceed the noise levels recommended by the WHO. This is because the elevated noise levels in military facilities, particularly from vehicular units and weaponry, compromise the combat medics' effectiveness and attentiveness to medical alarms. We previously designed a graphical ("configural") display to communicate patients' vital signs and found that when the configural display and traditional numerical display were concurrently presented to participants, it produced the fastest identification of patient vital signs and triggered the fewest number of alarms. This study used eye tracking to assess how participants direct visual attention to and engage with concurrently presented numerical and configural vital sign displays. We recruited 30 undergraduate students with normal hearing and vision for this study. Subjects were tasked with monitoring a simulated patient's vital signals using simultaneously presented numerical and configural vital sign displays. Concurrently, they performed an N-back task to simulate the multitasking required in a military environment. We manipulated the eccentricity and display position of the numerical and configural displays through 4 orientations, with each orientation being used in a monitoring block lasting 12 minutes. Continuous eye tracking was utilized to collect physiological data about participant display preference. We used eye tracking to analyze several metrics: Total display viewing time, total viewing time percentage, number of dwells (groups of eye fixations), mean fixations per dwell, and fixation patterns during an emergency event. Participants spent more time looking at the configural display than the numerical display during nominal monitoring and emergency events. During emergencies, the percentage of time individuals spent looking at the configural display increased from 30 to 50%, while there was no corresponding increase in the participants' looking at the numerical display. When there were 2 concurrent emergency events instead of 1, total viewing time did not increase, suggesting that participants did not need to change their viewing strategy when the emergency situation complexity increased. Also, during emergencies, participants directed nearly half of their fixations to the configural display during the first 2 seconds of an emergency, while only directing fewer than 5% of fixations to the numerical display during that same period. The average response time for an emergency event was around 2 seconds, which suggests that participants obtained relevant information from the configural display in this time period. We found that when a patient monitor contains both a configural display and a numerical display, participants look at the configural display. Furthermore, during time-sensitive situations, participants utilize the configural display to provide important information. We suggest this because the configural display integrates the relevant vital signs into one display. These findings provide justification for pursuing integrated vital sign displays to efficiently communicate patient conditions in complex environments. On the battlefield, swift decision-making is essential, as combat medics must minimize the time required to assess and act in critical situations.

Mindful Awareness Related to Working Memory Capacity and Response Inhibition

Objectives: This study investigated the associations among trait mindfulness, working memory capacity (WMC), and response inhibition. Mindfulness and WMC are thought to involve goal maintenance while resolving competing responses (inhibition), and studies have indeed found associations among mindfulness, WMC, and response inhibition. However, previous studies focused primarily on behavioral inhibition and many failed to differentiate components of mindfulness (awareness and acceptance). This study examined how self-reported mindfulness (awareness and acceptance) related to performance on tasks of WMC and multiple types of response inhibition (i.e., behavioral inhibition, interference control, and cognitive inhibition). Methods: Sixty-seven undergraduate students (75% female) received extra credit for participation. Measures included the Philadelphia Mindfulness Scale (measuring awareness and acceptance), Hayling Task (cognitive inhibition), go/nogo task (behavioral inhibition), Attention Network Test (interference control), n-back task (WMC), and Automated Reading Span Task (WMC). Results: Higher self-reported awareness was related to stronger performance on two measures of WMC (r =.29; r =.32) and multiple measures of response inhibition, including behavioral inhibition (r = -.25), interference control (r = -.25), and cognitive inhibition (r = -.28); response inhibition and WMC accounted for 22% and 16% of the variance in awareness respectively. No relations were found between self-reported acceptance and cognitive performance. Conclusions: Overall, this study found that the Mindfulness component of higher awareness (but not the component of acceptance) was related to stronger WMC and response inhibition. Because Mindfulness, WMC, and response inhibition are related in unique ways to healthy functioning and wellbeing; learning about how they interact increases scientific understanding, and suggests a direction for potential interventions to target these areas.

Individual Differences in Fatigued Performance

Cognitive fatigue is a prevalent issue across multiple military operational domains, resulting in degraded mission performance and costly mishaps. One approach to mitigating the effects of fatigue in operational environments is to develop technology, such as biomathematical, physiological, and cognitive models, that can help individuals assess and predict their fatigue and its impacts on performance. We can further enhance the accuracy of these models by incorporating individual difference metrics that allow for increased individualization. In the current study, we examine how individual differences in circadian typology, typical sleep duration, sleep duration need, and hardiness relate to fatigued performance during a 24-hr long mobility aircraft simulator session with mobility aircrews. Specifically, we examine individual difference relationships with performance on three cognitive tasks, the Psychomotor Vigilance Test, the N-back task, and the Change Signal Task, which measure processes crucial to operational performance: attention, working memory, and executive functioning.

Executive functions and divergent thinking in young adults: Evidence from individual differences and cognitive training studies

The interplay between executive functions and divergent thinking remains a debated question in creativity research. To address this issue, two studies were conducted from different perspectives. The first study explored which of the executive functioning components—namely working memory, inhibition, and shifting—predicted divergent thinking. A sample of 203 college students performed a battery of tasks assessing divergent thinking, executive functions, and related cognitive variables (fluid intelligence, verbal fluency, and processing speed). After statistically controlling for these variables, only working memory emerged as a significant predictor of creativity scores in the Alternative Uses Task, while inhibition and shifting did not. In the second study, a cognitive training approach was employed to further elucidate the potential efficacy of working memory training in fostering divergent thinking. The results found that the experimental group, which received a 15-day dual n-back task training, demonstrated greater improvements in the creativity score of the Alternative Uses Task compared to the control group, suggesting a transfer effect from working memory training to divergent thinking. This research underscores the plasticity of divergent thinking and highlights a plausible avenue for enhancing creativity through targeted cognitive training.

Is precrastination related to updating and inhibition aspects of executive function?

ABSTRACT Precrastination is the act of completing a task as soon as possible even at the expense of extra effort. Past research has suggested that individuals precrastinate due to a desire to reduce their cognitive load, also known as the cognitive load-reduction (CLEAR) hypothesis [VonderHaar, R. L., McBride, D. M., & Rosenbaum, D. A. (2019). Task order choices in cognitive and perceptual-motor tasks: The cognitive-load-reduction (CLEAR) hypothesis. Attention, Perception, & Psychophysics, 81(7), 2517–2525. https://doi.org/10.3758/s13414-019-01754-z]. This idea stems from the notion that it is taxing to hold intentions in working memory and completing a task as soon as possible releases cognitive resources for other tasks. Based on this hypothesis, we predicted that aspects of executive function may play a role in precrastination. We tested this prediction using a box-moving task developed in a previous study to measure precrastination. We also incorporated tasks measuring updating and inhibition aspects of executive function: the Stroop interference (both experiments) and Simon tasks (Experiment 2) to measure inhibition and the 2-Back memory task (Experiment 1) to measure updating. We found that the majority of participants precrastinated significantly throughout the box-moving task trials, consistent with results from past studies. However, no relation was found between the executive function tasks and rates of precrastination. These results may be due to the automaticity of precrastination when cognitive resources are limited.

Sub-bundle based analysis reveals the role of human optic radiation in visual working memory.

White matter (WM) functional activity has been reliably detected through functional magnetic resonance imaging (fMRI). Previous studies have primarily examined WM bundles as unified entities, thereby obscuring the functional heterogeneity inherent within these bundles. Here, for the first time, we investigate the function of sub-bundles of a prototypical visual WM tract-the optic radiation (OR). We use the 7T retinotopy dataset from the Human Connectome Project (HCP) to reconstruct OR and further subdivide the OR into sub-bundles based on the fiber's termination in the primary visual cortex (V1). The population receptive field (pRF) model is then applied to evaluate the retinotopic properties of these sub-bundles, and the consistency of the pRF properties of sub-bundles with those of V1 subfields is evaluated. Furthermore, we utilize the HCP working memory dataset to evaluate the activations of the foveal and peripheral OR sub-bundles, along with LGN and V1 subfields, during 0-back and 2-back tasks. We then evaluate differences in 2bk-0bk contrast between foveal and peripheral sub-bundles (or subfields), and further examine potential relationships between 2bk-0bk contrast and 2-back task d-prime. The results show that the pRF properties of OR sub-bundles exhibit standard retinotopic properties and are typically similar to the properties of V1 subfields. Notably, activations during the 2-back task consistently surpass those under the 0-back task across foveal and peripheral OR sub-bundles, as well as LGN and V1 subfields. The foveal V1 displays significantly higher 2bk-0bk contrast than peripheral V1. The 2-back task d-prime shows strong correlations with 2bk-0bk contrast for foveal and peripheral OR fibers. These findings demonstrate that the blood oxygen level-dependent (BOLD) signals of OR sub-bundles encode high-fidelity visual information, underscoring the feasibility of assessing WM functional activity at the sub-bundle level. Additionally, the study highlights the role of OR in the top-down processes of visual working memory beyond the bottom-up processes for visual information transmission. Conclusively, this study innovatively proposes a novel paradigm for analyzing WM fiber tracts at the individual sub-bundle level and expands understanding of OR function.

Single session and repeated anodal transcranial direct current stimulation over the right dorsolateral prefrontal cortex increases reflective thinking but not working memory updating performance

BackgroundAnodal transcranial direct current stimulation (tDCS) over the right dorsolateral prefrontal cortex (DLPFC) has shown to have effects on different domains of cognition yet there is a gap in the literature regarding effects on reflective thinking performance. ObjectiveThe current study investigated if single session and repeated anodal tDCS over the right DLPFC induces effects on judgment and decision-making performance and whether these are linked to working memory (updating) performance or cognitive inhibition. MethodsParticipants received anodal tDCS over the right DLPFC once (plus sham tDCS in a second session) or twice (24 h apart). In the third group participants received a single session of sham stimulation only. Cognitive characteristic measures were administered pre-stimulation (thinking disposition, impulsivity, cognitive ability). Experimental tasks included two versions of the Cognitive Reflection Test (numeric vs verbal-CRT), a set of incongruent base-rate vignettes, and two working memory tests (Sternberg task and n-back task). Forty-eight participants (mean age = 26.08 ± 0.54 years; 27 females) were recruited. ResultsSingle sessions of tDCS were associated with an increase in reflective thinking performance compared to the sham conditions, with stimulation improving scores on incongruent base rate tasks as well as marginally improving numeric CRT scores (compared to sham), but not thinking tasks without a numeric component (verbal-CRT). Repeated anodal stimulation only improved numeric CRT scores. tDCS did not increase working memory (updating) performance. These findings could not be explained by a practice effect or a priori differences in cognitive characteristics or impulsivity across the experimental groups. ConclusionThe current results demonstrate the involvement of the right DLPFC in reflective thinking performance which cannot be explained by working memory (updating) performance or general cognitive characteristics of participants.

Brain correlates of attentional load processing reflect degree of bilingual engagement: Evidence from EEG

The present study uses electroencephalography (EEG) with an N-back task (0-, 1-, and 2-back) to investigate if and how individual bilingual experiences modulate brain activity and cognitive processes. The N-back is an especially appropriate task given recent proposals situating bilingual effects on neurocognition within the broader attentional control system (Bialystok and Craik, 2022). Beyond its working memory component, the N-Back task builds in complexity incrementally, progressively taxing the attentional system. EEG, behavioral and language/social background data were collected from 60 bilinguals. Two cognitive loads were calculated: low (1-back minus 0-back) and high (2-back minus 0-back). Behavioral performance and brain recruitment were modeled as a function of individual differences in bilingual engagement. We predicted task performance as modulated by bilingual engagement would reflect cognitive demands of increased complexity: slower reaction times and lower accuracy, and increase in theta, decrease in alpha and modulated N2/P3 amplitudes. The data show no modulation of the expected behavioral effects by degree of bilingual engagement. However, individual differences analyses reveal significant correlations between non-societal language use in Social contexts and alpha in the low cognitive load condition and age of acquisition of the L2/2L1 with theta in the high cognitive load. These findings lend some initial support to Bialystok and Craik (2022), showing how certain adaptations at the brain level take place in order to deal with the cognitive demands associated with variations in bilingual language experience and increases in attentional load. Furthermore, the present data highlight how these effects can play out differentially depending on cognitive testing/modalities – that is, effects were found at the TFR level but not behaviorally or in the ERPs, showing how the choice of analysis can be deterministic when investigating bilingual effects.

The Effects of Auditory, Visual, and Cognitive Distractions on Cybersickness in Virtual Reality.

Cybersickness (CS) is one of the challenges that has hindered the widespread adoption of Virtual Reality (VR). Consequently, researchers continue to explore novel means to mitigate the undesirable effects associated with this affliction, one that may require a combination of remedies as opposed to a solitary stratagem. Inspired by research probing into the use of distractions as a means to control pain, we investigated the efficacy of this countermeasure against CS, studying how the introduction of temporally time-gated distractions affects this malady during a virtual experience featuring active exploration. Downstream of this, we studied how other aspects of the VR experience are affected by this intervention. We discuss the results of a between-subjects study manipulating the presence, sensory modality, and nature of periodic and short-lived (5-12 seconds) distractor stimuli across four experimental conditions: 1) no-distractors (ND); 2) auditory distractors (AD); 3) visual distractors (VD); 4) cognitive distractors (CD). Two of these conditions (VD and AD) formed a yoked control design wherein every matched pair of 'seers' and 'hearers' was periodically exposed to distractors that were identical in terms of content, temporality, duration, and sequence. In the CD condition, each participant had to periodically perform a 2-back working memory task, the duration and temporality of which was matched to distractors presented in each matched pair of the yoked conditions. These three conditions were compared to a baseline control group featuring no distractions. Results indicated that the reported sickness levels were lower in all three distraction groups in comparison to the control group. The intervention also increased the amount of time users were able to endure the VR simulation and avoided causing detriments to spatial memory and virtual travel efficiency. Overall, it appears that it may be possible to make users less consciously aware and bothered by the symptoms of CS, thereby reducing its perceived severity.

Unique versus shared neural correlates of externalizing psychopathology in late childhood.

Childhood externalizing psychopathology is heterogeneous. Symptom variability in conduct disorder (CD), oppositional defiant disorder (ODD), attention-deficit/hyperactivity disorder (ADHD), and callous-unemotional (CU) traits designate different subgroups of children with externalizing problems who have specific treatment needs. However, CD, ODD, ADHD, and CU traits are highly comorbid. Studies need to generate insights into shared versus unique risk mechanisms, including through the use of functional magnetic resonance imaging (fMRI). In this study, we tested whether symptoms of CD, ODD, ADHD, and CU traits were best represented within a bifactor framework, simultaneously modeling shared (i.e., general externalizing problems) and unique (i.e., symptom-specific) variance, or through a four-correlated factor or second-order factor model. Participants (N = 11,878, age, M = 9 years) were from the Adolescent Brain and Cognitive Development Study. We used questionnaire and functional magnetic resonance imaging data (emotional N-back task) from the baseline assessment. A bifactor model specifying a general externalizing and specific CD, ODD, ADHD, and CU traits factors demonstrated the best fit. The four-correlated and second-order factor models both fit the data well and were retained for analyses. Across models, reduced right amygdala activity to fearful faces was associated with more general externalizing problems and reduced dorsolateral prefrontal cortex activity to fearful faces was associated with higher CU traits. ADHD scores were related to greater right nucleus accumbens activation to fearful and happy faces. Results give insights into risk mechanisms underlying comorbidity and heterogeneity within externalizing psychopathology. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Multiple object tracking training affects the executive function in basketball players: the role of instant feedback

BackgroundThe present study aims to investigate the potential impact of eight sessions of Multiple Object Tracking (MOT) training on the executive function in basketball players. The purpose of the study was primarily to observe the effects of MOT training with and without feedback on the executive function of basketball players.MethodsA sample of fifty-eight participants was selected from college students enrolled in a university basketball special selection class. The participants were divided into three equal groups. The first group received MOT training with instant feedback and was called feedback group, the second group received MOT training without instant feedback and was called no feedback group, and the third group did not receive any intervention and was called control group.ResultsAfter eight sessions of MOT training, feedback group demonstrated the best performance in the Go/No-go task and the 3-back task. After eight sessions of MOT training, there was no significant difference in test scores on the Stroop task between the feedback and no feedback groups. There was also no significant difference in test scores between the feedback and no feedback groups on the 2-back task after eight sessions of MOT training. The findings of this study suggest that MOT training can effectively enhance the executive function of basketball players.ConclusionsMOT training was found to enhance the executive function of basketball players, irrespective of whether they received instant feedback. However, the feedback group exhibited superior improvements in the Go/No-go task and the 3-back task.

Exploring the effects of combining health qigong and dance on working memory in middle-aged and elderly women: A preliminary investigation

ObjectiveCognitive decline represents a critical clinical and public health issue that adversely affects the quality of life for older patients and their families. This concern was exacerbated by the reduced engagement in outdoor activities among seniors during the COVID-19 pandemic, presenting substantial challenges to aging societies. The objective of this study was to investigate the impact of health qigong combined with Tibetan dance on working memory in middle-aged and elderly women, and to determine its potential as a preventive strategy against cognitive disorders. MethodsA pilot study was conducted to compare the effects of a Health Qigong exercise intervention with those of everyday life and sports routines. The primary outcome measure was working memory assessed using a 2-Back working memory task research paradigm. Between July and September 2021, a total of 33 women were divided into four groups: two middle-aged groups (N = 18, with 8 women in the experimental group and 10 in the control group) and two elderly groups (N = 15, with 7 in the experimental group and 8 in the control group). Participants in the experimental groups underwent a 10-week intervention, consisting of three 60-min sessions per week. Each session included a warm-up, Health Qigong combined with Tibetan dance, and a cool-down. Throughout the study, all participants continued their daily routines. Response times and error rates were analyzed using a mixed-design repeated-measures analysis of variance. ResultsA simple effects analysis revealed that Health Qigong combined with Tibetan dance significantly enhanced 2-Back response time and error rate in the middle-aged group. In contrast, the 2-Back error rate significantly increased in the elderly control group that did not receive the intervention (p < 0.05). ConclusionHealth Qigong demonstrates beneficial effects on middle-aged and elderly women. Combining Health Qigong with dance may serve as a preventive measure against cognitive disorders. This pioneering study conducted during the COVID-19 pandemic, assesses the new possibility of Health Qigong and dance, with the objective to offer more diverse indoor exercise options for middle-aged and elderly women.

A preliminary investigation of sex differences in cognitive and fMRI changes following 28 days of cannabis abstinence

BackgroundPrevious studies have investigated the influence of cannabis on cognition among people with MS (pwMS), yet the influence of sex in the context of cannabis use remains unexplored. We aim to fill this gap by investigating cannabis-sex related differences in verbal learning, memory and processing speed in association with fMRI (resting state, and task-based) metrics. MethodOur sample consisted of 19 long-term, frequent cannabis users (8 males, 11 females). Assessments were conducted at baseline and after 28 days of cannabis abstinence. The tests included measures of verbal memory (Selective Reminding Test (SRT)), working memory (n-back), information processing speed (Symbol Digit Modalities Test (SDMT)) and the resting state DMN. To evaluate the effects of cannabis abstinence, we performed a group x time interaction analysis using repeated measures ANCOVA. This analysis controlled for several covariates, including the level of disability (EDSS), baseline cannabis THC metabolite levels, and cannabis withdrawal symptoms. By controlling for these variables, we aimed to isolate the impact of cannabis abstinence on cognitive performance over time. Statistical significance was set at p < 0.05. ResultsThere were no baseline cognitive differences between the sexes. After 28 days of cannabis abstinence, females performed better on the Selective Reminding Test (SRT) (p = 0.04), with a large effect size (η² = 0.286). The mean correct response improved over time for females, but there was no statistically significant group x time interaction on the Symbol Digit Modalities Test (SDMT) and the n-back task. Resting state default mode network data showed overall increased activation in females relative to males at day 28, which meshed with lower brain activation during task-based fMRI paradigms. ConclusionCannabis negated sex-based cognitive differences. Functional MRI task-based paradigms revealed less cerebral activation in females compared to males, which was associated with comparable or better cognitive performance in females, particularly after cannabis abstinence.

Frontoparietal Response to Working Memory Load Mediates the Association between Sleep Duration and Cognitive Function in Children.

Lack of sleep has been found to be associated with cognitive impairment in children, yet the neural mechanism underlying this relationship remains poorly understood. To address this issue, this study utilized the data from the Adolescent Brain Cognitive Development (ABCD) study (n = 4930, aged 9-10), involving their sleep assessments, cognitive measures, and functional magnetic resonance imaging (fMRI) during an emotional n-back task. Using partial correlations analysis, we found that the out-of-scanner cognitive performance was positively correlated with sleep duration. Additionally, the activation of regions of interest (ROIs) in frontal and parietal cortices for the 2-back versus 0-back contrast was positively correlated with both sleep duration and cognitive performance. Mediation analysis revealed that this activation significantly mediated the relationship between sleep duration and cognitive function at both individual ROI level and network level. After performing analyses separately for different sexes, it was revealed that the mediation effect of the task-related activation was present in girls (n = 2546). These findings suggest that short sleep duration may lead to deficit in cognitive function of children, particularly in girls, through the modulation of frontoparietal activation during working memory load.

Effect of transcranial direct current stimulation with concurrent cognitive performance targeting posterior parietal cortex vs prefrontal cortex on working memory in schizophrenia: a randomized clinical trial

Working memory deficits are linked to irregularities in the dorsolateral prefrontal cortex (DLPFC) and the posterior parietal cortex (PPC) in schizophrenia, effective intervention strategies are lacking. We evaluated the differential efficacy and underlying neuromechanisms of targeting transcranial direct current stimulation (tDCS) at the DLPFC and the PPC with concurrent cognitive performance for working memory in schizophrenia. In a randomized and double-blind clinical trial, sixty clinically stable schizophrenic patients with below-average working memory were randomly assigned to active DLPFC, active PPC, and sham tDCS groups. Two sessions of tDCS during N-back task were delivered daily for five days. The primary outcome was changes in spatial span test scores from baseline to week 1. The secondary outcomes included changes in scores of color delay-estimation task, other cognitive tasks, and mismatch negativity (biomarker of N-methyl-d-aspartate receptor functioning). Compared with the active DLPFC group, the active PPC group demonstrated significantly greater improvement in spatial span test scores (p = 0.008, d = 0.94) and an augmentation in color delay-estimation task capacity at week 1; the latter sustained to week 2. Compared with the sham tDCS group, the active PPC group did not show a significant improvement in spatial span test scores at week 1 and 2; however, significant enhancement was observed in their color delay-estimation task capacity at week 2. Additionally, mismatch negativity amplitude was enhanced, and changes in theta band measures were positively correlated with working memory improvement in the active PPC group, while no such correlations were observed in the active DLPFC group or the sham tDCS group. Our results suggest that tDCS targeting the PPC relative to the DLPFC during concurrent cognitive performance may improve working memory in schizophrenia, meriting further investigation. The improvement in working memory appears to be linked to enhanced N-methyl-d-aspartate receptor functioning.

Aberrant brain dynamics in major depressive disorder during working memory task.

Working memory (WM) is a distributed and dynamic process, and WM deficits are recognized as one of the top-ranked endophenotype candidates for major depressive disorders (MDD). However, there is a lack of knowledge of brain temporal-spatial profile of WM deficits in MDD. We used the dynamical degree centrality (dDC) to investigate the whole-brain temporal-spatial profile in 40 MDD and 40 controls during an n-back task with 2 conditions (i.e., '0back' and '2back'). We explored the dDC temporal variability and clustered meta-stable states in 2 groups during different WM conditions. Pearson's correlation analysis was used to evaluate the relationship between the altered dynamics with clinical symptoms and WM performance. Compared with controls, under '2back vs. 0back' contrast, patients showed an elevated dDC variability in wide range of brain regions, including the middle frontal gyrus, orbital part of inferior frontal gyrus (IFGorb), hippocampus, and middle temporal gyrus. Furthermore, the increased dDC variability in the hippocampus and IFGorb correlated with worse WM performance. However, there were no significant group-related differences in the meta-stable states were observed. This study demonstrated the increased WM-related instability (i.e., the elevated dDC variability) was represented in MDD, and enhancing stability may help patients achieve better WM performance.

Effects of different types of leisure activities on working memory across the adult lifespan

The aim of the present study was to contrast the potential influence of five independent types of leisure activities (physical, mental, social, cultural, and passive) on working memory in a lifespan sample and in specific stages of adulthood (young, middle-aged, and older adults). A sample of 1652 healthy adults between 21 and 80 years of age participated in the study. Leisure activities were assessed through a lifestyle questionnaire created for the study. Working memory was measured in the verbal and spatial domains using a computerized n-back task that allowed us to reliably measure discrimination and reaction times. Across adulthood, mental (computer use and hobbies) and social leisure activities predicted greater verbal and spatial working memory discrimination; mental (reading) and social activities predicted faster verbal working memory; and mental (computer use) and physical activities predicted faster spatial working memory. In young adults, mental (computer use) and social activities were associated with greater verbal and spatial working memory performance. In middle-aged adults, physical and mental activities (computer use) were associated with greater working memory performance. In older adults, physical, mental (hobbies), and social activities were associated with greater working memory performance. Leisure activities can enhance working memory discrimination and speed independent of individuals’ age.