2-back Condition Research Articles

THE PHYSIOLOGIC COMPLEXITY OF PREFRONTAL OXYGENATION DYNAMICS IS ASSOCIATED WITH AGE AND COGNITIVE FUNCTION

Abstract The hemodynamics of prefrontal cortex (PFC) oxygenation are regulated by numerous elements over multiple temporal scales. The dynamics in the fluctuations of PFC oxygenation are thus complex. Age may alter the multiscale regulation of PFC oxygenation, leading to diminished physiologic complexity of this important regulatory process. We aimed to characterize the effects of age and cognitive demand on such complexity in younger and older adults and its relationship to cognitive performance. Twenty-four younger (aged 28±3 years) and 27 older adults (aged 78±6 years) completed this study. The oxygenation (HbO2) and deoxygenation (HHb) signals of the PFC were recorded using functional near-infrared-spectroscopy (fNIRS) during the n-back task of blank, identification-of-X (IdX), and 2-back conditions. We used multiscale entropy to quantify the HbO2 and HHb complexity of fNIRS. It was observed that older adults exhibited lower fNIRS complexity regardless of task condition (p=0.0005) and lower percent increase of complexity from blank (p=0.02) or IdX (p=0.01) to 2-back compared to younger. Both groups exhibited greater complexity during IdX and 2-back compared to blank condition (p< 0.02). Those with greater HbO2 complexity had greater 2-back accuracy (p=0.02~0.04). Older adults with greater fNIRS complexity had faster reaction times (β=-0.56~-0.6, p=0.009~0.02); while younger with lower complexity had faster reaction times (β=0.58~0.62, p=0.01~0.02). Participants with greater increase of fNIRS complexity from blank to 2-back had faster 2-back reaction time (β=-0.68~-0.49, p=0.001~0.03). The complexity of fNIRS-measured PFC oxygenation fluctuations may capture the influence of aging and task demands on the regulation of prefrontal hemodynamics involved in cognitive task execution.

Machine learning based on event-related oscillations of working memory differentiates between preclinical Alzheimer’s disease and normal aging

ObjectiveTo apply machine learning approaches on EEG event-related oscillations (ERO) to discriminate preclinical Alzheimer’s disease (AD) from age- and sex-matched controls. MethodsTwenty-two cognitively normal preclinical AD participants with elevated amyloid and 21 cognitively normal controls without elevated amyloid completed n-back working memory tasks (n = 0, 1, 2). The absolute and relative power of ERO was extracted using the discrete wavelet transform in the delta, theta, alpha, and beta bands. Four machine learning methods were employed, and classification performance was assessed using three metrics. ResultsThe low-frequency bands produced higher discriminative performances compared to high-frequency bands. The 2-back task yielded the best classification capability among the three tasks. The highest area under the curve value (0.86) was achieved in the 2-back delta band nontarget condition data. The highest accuracy (80.47%) was obtained in the 2-back delta and theta bands nontarget data. The highest F1 score (0.82) was in the 2-back theta band nontarget data. The support vector machine achieved the highest performance among tested classifiers. ConclusionThis study demonstrates the promise of using machine learning on EEG ERO from working memory tasks to detect preclinical AD. SignificanceEEG ERO may reveal pathophysiological differences in the earliest stage of AD when no cognitive impairments are apparent.

Age-related cerebral changes during different n-back tasks: a functional near-infrared spectroscopy study.

The n-back task is a widely used paradigm to assess working memory and is commonly applied in research on age-related cognitive decline. However, studies utilizing functional near-infrared spectroscopy (fNIRS) to explore this area are limited. This study aims to investigate age-related differences in brain activation during the n-back task using fNIRS. fNIRS data were collected from 18 elderly and 19 young participants while performing different n-back tasks. Brain activation patterns and peripheral performance were compared between the two groups. Significant differences in brain activation patterns were observed between elderly and young participants. Under the 3-back condition, the older group exhibited reduced activation in brain regions adjacent to prefrontal cognitive areas compared to the younger group. Additionally, the older group's performance plateaued at the 2-back level, along with a decline in prefrontal activation. These findings may suggest potential markers for cognitive decline, providing a new target for future screening.

The characteristics of WM in individuals with depressive tendencies: A functional near-infrared spectroscopy (fNIRS) study

Individuals with depressive tendencies are considered to be at high risk for the onset of depressive disorders. Currently, most research focuses on the impairment of working memory in patients with depression, while there is less attention paid to the WM of individuals with depressive tendencies, and their neural mechanisms underlying it are poorly understood. Therefore, this study focuses on the characteristics and neural mechanisms of WM in individuals with depressive tendencies. This study uses functional near-infrared spectroscopy (fNIRS) to monitor the concentration of Oxy-Hb in the prefrontal cortex and employs the n-back paradigm, designing three levels of load: 0, 1, and 2, to examine the characteristics of WM and its neural mechanisms in individuals with depressive tendencies. Behavioral results show that the accuracy rates of individuals with depressive tendencies is significantly lower than that of healthy individuals, and under the 0-back condition, the reaction time of individuals with depressive tendencies is significantly higher than that of healthy control individuals. Near-infrared results indicate that the activation level in the frontal pole and the dorsal lateral prefrontal cortex of individuals with depressive tendencies is significantly lower than that of healthy control individuals. The β values of channels 2, 7, and 9 are significantly negatively correlated with the Beck Depression Inventory scores of the participants. The results suggest that the reduced activation of the frontal pole and dorsal lateral prefrontal cortex in individuals with depressive tendencies leads to poorer WM performance compared to healthy control individuals. This is a rare brain evidence of the characteristics of WM in individuals with depressive tendencies, which can provide a deeper understanding of the WM characteristics of individuals with depressive tendencies.

Neural mechanisms of the relationship between aerobic fitness and working memory in older adults: An fNIRS study

Abstract A growing number of studies have revealed that higher aerobic fitness is associated with better working memory (WM) performance in older adults. However, the underlying functional neural mechanisms of this association remain under debate. It has been reported that aging increases recruitment of the prefrontal cortex (PFC) during cognitive tasks, and that this is associated with task performance in a compensatory manner. Therefore, this study aimed to clarify the prefrontal activation pattern that is associated with the relationship between aerobic fitness and WM performance in older adults, focusing on age-related extended prefrontal recruitment. Forty-seven older adults (65–74 years, 29 females) and 49 younger adults (18–24 years, 23 female) performed verbal and spatial n-back tasks, which included 0-, 1-, and 2-back conditions. Reaction time (RT) and accuracy (ACC) were assessed as indices of task performance. Prefrontal activation during the experimental tasks was monitored using functional near-infrared spectroscopy (fNIRS) and analyzed using an adaptive GLM method. We compared task performance and prefrontal activation between age groups to find age-related prefrontal activation patterns. Only older adults underwent a graded exercise test (GXT) to determine their ventilation thresholds (VT) as a measure of aerobic fitness, and, subsequently, the relationships among aerobic fitness, n-back task performance, and prefrontal activation in older adults were examined using correlation analysis and mediation analysis controlling for possible covariates. A comparison of task performance between groups revealed that older adults had slower RT and lower ACC than did younger adults, especially in the higher WM load 2-back condition. Group comparisons of prefrontal activation showed that older adults exhibited additional or greater activation than younger adults mainly in the ventrolateral PFC (VLPFC) and front polar area (FPA) in both the verbal and spatial 2-back conditions. Correlation analysis showed a relationship between higher VT, shorter RT for the verbal 2-back condition, and greater prefrontal activation of the bilateral FPA and right VLPFC during verbal 2-back conditions in older adults. In addition, mediation analyses indicated the possibility of a mediation effect of the prefrontal activation on the relationship between VT and RT for the verbal 2-back condition. These results suggest that older adults with higher aerobic fitness levels recruited more extended PFC regions, possibly for compensatory activation, to enhance their performance of the verbal n-back task. This study sheds light on the neural mechanisms underpinning the relationship between aerobic fitness and cognitive function in older adults.

P159 Development of digital neuropsychological battery: a use case in Indian SLE patients

Abstract Background/Aims While cognitive dysfunction and mood disorders are frequently reported as adverse effects of SLE, there is a scarcity of neuropsychological (NP) data for Asian SLE patients. Existing English-centric NP tests are inadequate for the linguistic and culturally diverse population. This study examines SLE's effects on mood and cognitive functions using an indigenously developed language-neutral digital NP test battery and validated anxiety, stress, depression and quality of life instruments. Methods We recruited SLE patients fulfilling 2012 SLE classification criteria as cases and caregivers (CG) and college students (CS) as controls aged above 18 years and at least 10th standard education. All participants provided written informed consent. Institutional ethics committees approved the study. The NP battery comprised five cognitive tasks: Montreal Cognitive Assessment (MoCA) and modified versions of attention network test (ANT), sustained attention to response task (SART), picture naming and N-back, and five psychological tests (PHQ-9, GAD-7, STAI-T, PSS-4 and WHOQOL-BREF). Mann-Whitney test with conditional Bonferroni's corrections was used to compare cases with CG and CS. Results Total of 142 volunteers (age: median = 25.0, IQR = 9.0, cases [n = 82], CG [n = 40] and CS [n = 20]) participated in the study. Cases exhibited delayed response latencies in N-back, SART, and picture naming tasks compared to controls. They demonstrated reduced accuracy in all N-back conditions, with significant differences observed in hit rate, miss rate, false alarms, and d-prime scores compared to CS with effect size ranging from 0.298 to 0.736 (Table 1). However, the difference was only significant in the 2-back condition compared to CG. Cases displayed lower accuracy in SART Go trials (higher omission errors) than controls but better inhibition in SART No-Go trials (lower commission errors). No differences were observed in alerting, orienting and executive control functions. Cases showed significantly lower scores in MOCA than controls. Cases reported poorer psychological health through increased anxiety and stress levels and reduced WHO-quality of life scores compared to CG. Conclusion Contrary to earlier research that often relied on isolated cognitive assessments, our pioneering approach introduces a tailored test battery to establish cognitive baselines for Indian SLE patients. Disclosure P. Singhal: None. P. Srivastava: None. L. Rajasekhar: None. N. Samhitha: None.

Functional and structural connectivity success predictors of real-time fMRI neurofeedback targeting DLPFC: Contributions from central executive, salience, and default mode networks.

Real-time functional magnetic resonance imaging (rt-fMRI) neurofeedback (NF), a training method for the self-regulation of brain activity, has shown promising results as a neurorehabilitation tool, depending on the ability of the patient to succeed in neuromodulation. This study explores connectivity-based structural and functional success predictors in an NF n-back working memory paradigm targeting the dorsolateral prefrontal cortex (DLPFC). We established as the NF success metric the linear trend on the ability to modulate the target region during NF runs and performed a linear regression model considering structural and functional connectivity (intrinsic and seed-based) metrics. We found a positive correlation between NF success and the default mode network (DMN) intrinsic functional connectivity and a negative correlation with the DLPFC-precuneus connectivity during the 2-back condition, indicating that success is associated with larger uncoupling between DMN and the executive network. Regarding structural connectivity, the salience network emerges as the main contributor to success. Both functional and structural classification models showed good performance with 77% and 86% accuracy, respectively. Dynamic switching between DMN, salience network and central executive network seems to be the key for neurofeedback success, independently indicated by functional connectivity on the localizer run and structural connectivity data.

Greater up-modulation of intra-individual brain signal variability makes a high-load cognitive task more arduous for older adults

The extent to which brain responses are less distinctive across varying cognitive loads in older adults is referred to as neural dedifferentiation. Moment-to-moment brain signal variability, an emerging indicator, reveals not only the adaptability of an individual's brain as an inter-individual trait, but also the allocation of neural resources within an individual due to ever-changing task demands, thus shedding novel insight into the process of neural dedifferentiation. However, how the modulation of intra-individual brain signal variability reflects behavioral differences related to cognitively demanding tasks remains unclear. In this study, we employed functional near-infrared spectroscopy (fNIRS) imaging to capture the variability of brain signals, which was quantified by the standard deviation, during both the resting state and an n-back task (n = 1, 2, 3) in 57 healthy older adults. Using multivariate Partial Least Squares (PLS) analysis, we found that fNIRS signal variability increased from the resting state to the task and increased with working memory load in older adults. We further confirmed that greater fNIRS signal variability generally supported faster and more stable response time in the 2- and 3-back conditions. However, the intra-individual level analysis showed that the greater the up-modulation in fNIRS signal variability with cognitive loads, the more its accuracy decreases and mean response time increases, suggesting that a greater intra-individual brain signal variability up-modulation may reflect decreased efficiency in neural information processing. Taken together, our findings offer new insights into the nature of brain signal variability, suggesting that inter- and intra-individual brain signal variability may index distinct theoretical constructs.

Identification of cognitive load-dependent activation patterns using working memory task-based fMRI at various levels of difficulty

Working memory, which is regarded as the foundation of cognitive processes, is a system that stores, processes, and manipulates information in short intervals of time that are actually needed for daily functioning. This study aimed to assess the brain activity of healthy controls (HC) while performing the N-back task, which is one of the most popularly used tests for evaluating working memory along with functional magnetic resonance imaging (fMRI). In this regard, we collected fMRI data from right-handed individuals in a 3.0 T scanner during the Persian version of the visual variant N-back task performance with three levels of complexity varied throughout the experiment (1, 2, and 3-back conditions) to increase the cognitive demands. The statistical parametric mapping (SPM12) software was used to analyze fMRI data for the identification of cognitive load-dependent activation patterns based on contrast images obtained from different levels of task difficulty. Our findings showed that as cognitive complexity increased, the number of significant activation clusters and cluster extent increased in several areas distributed in the cerebellum, frontoparietal lobes, insula, SMA, and lenticular nucleus, the majority of which are recognized for their role in working memory. Furthermore, deactivation patterns during 1-, 2-, and 3-back vs. 0-back contrasts revealed significant clusters in brain regions that are mostly described as being part of the default mode network (DMN). Based on previous research, our results supported the recognized involvement of the mentioned cortical and subcortical areas in various types or levels of N-back tasks. This study found that altering activation patterns by increasing task difficulty could aid in evaluating the various stages of cognitive dysfunction in many brain diseases such as multiple sclerosis (MS) and Alzheimer's disease by comparing controls in future studies to apply early appropriate treatment strategies.

Cognitive Load and Deception Detection Performance.

The ability to detect deception is one of the most intriguing features of our minds. Cognitive load can surprisingly increase the accuracy of detection when there is a substantial load compared to when the detection is performed without cognitive load. This effect was tested in two experiments. In the first experiment, the participants were asked to watch truth/lie videos while completing a concurrent task (N-back in a 3-back version; intuitive processing), providing verbal reasoning after watching each video (deliberative processing), or watching the videos alone (control group). The cognitive load caused by the concurrent task led to a higher accuracy in deception detection compared to the other conditions. In the second experiment, we examined how this effect worked under various amounts of cognitive load. Participants watching truth/lie videos were assigned to one of three experimental conditions (N-back in three versions: 1, 3, and 5-back) or to a control group. The participants in the 3-back and 5-back conditions exhibited a significantly higher accuracy in deception detection than those in the 1-back and control groups. Thus, the effect of increased accuracy in deception detection is due to cognitive load and is related to the amount of cognitive load present.

Audiovisual n-Back Training Alters the Neural Processes of Working Memory and Audiovisual Integration: Evidence of Changes in ERPs.

(1) Background: This study investigates whether audiovisual n-back training leads to training effects on working memory and transfer effects on perceptual processing. (2) Methods: Before and after training, the participants were tested using the audiovisual n-back task (1-, 2-, or 3-back), to detect training effects, and the audiovisual discrimination task, to detect transfer effects. (3) Results: For the training effect, the behavioral results show that training leads to greater accuracy and faster response times. Stronger training gains in accuracy and response time using 3- and 2-back tasks, compared to 1-back, were observed in the training group. Event-related potentials (ERPs) data revealed an enhancement of P300 in the frontal and central regions across all working memory levels after training. Training also led to the enhancement of N200 in the central region in the 3-back condition. For the transfer effect, greater audiovisual integration in the frontal and central regions during the post-test rather than pre-test was observed at an early stage (80-120 ms) in the training group. (4) Conclusion: Our findings provide evidence that audiovisual n-back training enhances neural processes underlying a working memory and demonstrate a positive influence of higher cognitive functions on lower cognitive functions.

626-P: Integrated Approach of Yoga Therapy (IAYT) Improves Cerebrovascular Functions and Prefrontal Hemodynamic Activities Related to Cognition in Type 2 Diabetes

The present study aimed to assess the integrated approach of yoga therapy (IAYT) effect on cerebrovascular reactivity in middle cerebral artery (MCA), prefrontal cortex (PFC) oxygenation and cognitive functions in patients with T2DM. Method: 75 patients were randomized to the IAYT group [n=38; 07 female; mean age 52.95 (8.20) years] and the waitlist control group [n=37; 06female; mean age (SD) 49.62 (10.94) years]. The cerebral blood flow and prefrontal hemodynamic activities were assessed using transcranial doppler and functional near-infrared spectroscopy, respectively, during resting and cognitive performance. IAYT group participants received 3 months of intervention and assessments were done at baseline (0-week), mid (after 6-week), and post (after 12-week). Results: After a 12-week intervention, participants of the yoga group showed improved accuracy and reaction time in a 2-back condition of the working memory task, and the scores of the Corsi Block Tapping task. Further, cerebrovascular changes were observed in the middle cerebral artery, which showed increased peak systolic velocity, mean blood flow velocity, end-diastolic velocity, and breath-holding index after 12-week yoga practice. The oxygenation was also higher at dorsolateral, dorsomedial, and ventromedial and orbitofrontal PFC in the 12th week of the yoga practitioners group compared to the control group. Moreover, during 2-back working memory task, yoga group participants demonstrated increased oxygenation at dorsolateral PFC compared to pre and higher oxygenation at dorsolateral, ventrolateral, ventromedial and orbitofrontal PFC compared to control group. Conclusion: The results suggest that IAYT practice may improve cognitive functions by improving cerebral blood flow through the middle cerebral artery and hemodynamic activities in the prefrontal regions in patients with T2DM. Disclosure D.Singh: None. C.Kaligal: None. V.M: None. A.Kanthi: None. Funding Ministry of Ayush, Government of India (Z.280152092015-HPC(EMR)-AYUSH)

TAG-ME again: A serious game for measuring working memory

BrainTagger (demo version: researcher-demo.braintagger.com) is a suite of Target Acquisition Games for Measurement and Evaluation (TAG-ME). Here we introduce TAG-ME Again, a serious game modeled after the well-established N-Back task, to assess working memory ability across three difficulty levels corresponding to 1-, 2-, and 3-back conditions. We also report on two experiments aimed at assessing convergent validity with the N-Back task. Experiment 1 examined correlations with N-Back task performance in a sample of adults (n = 31, 18–54 years old) across three measures: reaction time; accuracy; a combined RT/accuracy metric. Significant correlations between game and task were found, with the strongest relationship being for the most difficult version of the task (3-Back). In Experiment 2 (n = 66 university students, 18–22 years old), we minimized differences between the task and the game by equating stimulus-response mappings and spatial processing demands. Significant correlations were found between game and task for both the 2-Back and 3-Back levels. We conclude that TAG-ME Again is a gamified task that has convergent validity with the N-Back Task.

Changes in task performance and frontal cortex activation within and over sessions during the n-back task

The n-back task is a popular paradigm for studying neurocognitive processing at varying working memory loads. Although much is known about the effects of load on behavior and neural activation during n-back performance, the temporal dynamics of such effects remain unclear. Here, we investigated the within- and between-session stability and consistency of task performance and frontal cortical activation during the n-back task using functional near-infrared spectroscopy (fNIRS). Forty healthy young adults performed the 1-back and 3-back conditions three times per condition. They then undertook identical retest sessions 3 weeks later (M = 21.2 days, SD = 0.9). Over the course of the task, activation in the participants’ frontopolar, dorsomedial, dorsolateral, ventrolateral, and posterolateral frontal cortices was measured with fNIRS. We found significantly improved working memory performance (difference between 1-back and 3-back accuracies) over time both within and between sessions. All accuracy and reaction time measures exhibited good to excellent consistency within and across sessions. Additionally, changes in frontal oxyhemoglobin (HbO) and deoxyhemoglobin (HbR) concentration were maintained over time across timescales, except that load-dependent (3-back > 1-back) HbO changes, particularly in the ventrolateral PFC, diminished over separate sessions. The consistency of fNIRS measures varied greatly, with changes in 3-back dorsolateral and ventrolateral HbO demonstrating fair-to-good consistency both within and between sessions. Overall, this study clarified the temporal dynamics of task performance and frontal activation during the n-back task. The findings revealed the neural mechanisms underlying the change in n-back task performance over time and have practical implications for future n-back research.

Transcranial direct current stimulation over the right dorsolateral prefrontal cortex increases oxyhemoglobin concentration and cognitive performance dependent on cognitive load

Transcranial direct current stimulation (tDCS) has been explored as a potential method for cognitive enhancement. tDCS may induce a cascade of neurophysiological changes including alterations in cerebral oxygenation. However, the effects of tDCS on the cognitive-cerebral oxygenation interaction remains unclear. Further, oxygenation variability across individuals remains minimally controlled for. The purpose of this sham-controlled study was to test the effects of anodal tDCS over the right dorsolateral prefrontal cortex (DLPFC) on the interaction between working memory and cerebral oxygenation while controlling for individual oxygenation variability. Thirty-three adults received resting-state functional near-infrared spectroscopy (fNIRS) recordings over bilateral prefrontal cortices. Following this, working memory was tested using a Toulouse n-back task concurrently paired with fNIRS, with measurements taken before and after 20 min of anodal or sham tDCS at 1.5 mA. With individual oxygenation controlled for, anodal tDCS was found to increase the oxyhemoglobin concentration over the right DLPFC during the 2-back (q = .015) and 3-back (q = .008) conditions. Additionally, anodal tDCS was found to improve accuracy during the 3-back task by 13.4 % (p = .028) and decrease latency by 250 ms (p = .013). The increase in oxyhemoglobin was strongly correlated with increases in accuracy (p = .041) and decreases in latency during the 3-back span (p = .017). Taken together, anodal tDCS over the right DLPFC was found to regionally increase oxyhemoglobin concentrations and improve working memory performance in higher cognitive load conditions.

Functional near-infrared spectroscopy measures of neural activity in children with and without developmental language disorder during a working memory task.

Children with developmental language disorder (DLD) exhibit cognitive deficits that interfere with their ability to learn language. Little is known about the functional neuroanatomical differences between children developing typically (TD) and children with DLD. Using functional near-infrared spectroscopy, we recorded oxygenated hemoglobin (O2 hb) concentration values associated with neural activity in children with and without DLD during an auditory N-back task that included 0-back, 1-back, and 2-back conditions. Analyses focused on the left dorsolateral prefrontal cortex (DLPFC) and left inferior parietal lobule (IPL). Multilevel models were constructed with accuracy, response time, and O2 hb as outcome measures, with 0-back outcomes as fixed effects to control for sustained attention. Children with DLD were significantly less accurate than their TD peers at both the 1-back and 2-back tasks, and they demonstrated slower response times during 2-back. In addition, children in the TD group demonstrated significantly greater sensitivity to increased task difficulty, showing increased O2 hb to the IPL during 1-back and to the DLPFC during the 2-back, whereas the DLD group did not. A secondary analysis revealed that higher O2 hb in the DLPFC predicted better task accuracy across groups. When task difficulty increased, children with DLD failed to recruit the DLPFC for monitoring information and the IPL for processing information. Reduced memory capacity and reduced engagement likely contribute to the language learning difficulties of children with DLD.

Functional connectivity changes during working memory in autism spectrum disorder: A two-year longitudinal MEG study

Working memory impairments have been reported in adults with autism spectrum disorder (ASD) and associated with functional outcomes and social difficulties. However, little is known about the developmental trajectory of working memory in youth with ASD. The current magnetoencephalography (MEG) study is the first to examine the longitudinal development over two years of working memory networks in youth with ASD. We analysed MEG data from 32 children and adolescents with and without ASD (64 datasets; 7–14 years), all tested twice at a two-year interval, during a visual n-back task, with two loads (1- and 2-back). We performed a whole-brain functional connectivity analysis to examine the networks during the successful recognition of visual stimuli. We demonstrate that youth with ASD show decreased connectivity in the theta frequency (4–7 Hz) in the higher memory load (2-back) condition compared to typically developing (TD) controls. This hypo-connected theta network was anchored in primary visual areas with connections to frontal, parietal and limbic regions. These network differences were found despite similar task performance between ASD and TD groups. Within the TD group, we found an increase in alpha (8–14 Hz) connectivity at Time 2 compared to Time 1 in both the 1- and 2-back conditions. These findings demonstrate the continued development of working memory mechanisms over middle childhood, which were not apparent in youth with ASD. Together, our findings support a network-based approach to understanding atypical neural functioning in ASD and the developmental trajectories of working memory processes over middle childhood.

Event-related microstate dynamics represents working memory performance

In recent years, EEG microstate analysis has attracted much attention as a tool for characterizing the spatial and temporal dynamics of large-scale electrophysiological activities in the human brain. Canonical 4 states (classes A, B, C, and D) have been widely reported, and they have been pointed out for their relationships with cognitive functions and several psychiatric disorders such as schizophrenia, in particular, through their static parameters such as average duration, occurrence, coverage, and transition probability. However, the relationships between event-related microstate changes and their related cognitive functions, as is often analyzed in event-related potentials under time-locked frameworks, is still not well understood. Furthermore, not enough attention has been paid to the relationship between microstate dynamics and static characteristics.To clarify the relationships between the static microstate parameters and dynamic microstate changes, and between the dynamics and working memory (WM) function, we first examined the temporal profiles of the microstates during the N-back task. We found significant event-related microstate dynamics that differed predominantly with WM loads, which were not clearly observed in the static parameters. Furthermore, in the 2-back condition, patterns of state transitions from class A to C in the high- and low-performance groups showed prominent differences at 50–300 ms after stimulus onset. We also confirmed that the transition patterns of the specific time periods were able to predict the performance level (low or high) in the 2-back condition at a significant level, where a specific transition between microstates, namely from class A to C with specific polarity, contributed to the prediction robustly. Taken together, our findings indicate that event-related microstate dynamics at 50–300 ms after onset may be essential for WM function. This suggests that event-related microstate dynamics can reflect more highly-refined brain functions.

Slow yoga breathing improves mental load in working memory performance and cardiac activity among yoga practitioners.

This study investigated the immediate effect of slow yoga breathing (SYB) at 6 breaths per minute (bpm) simultaneously on working memory performance and heart rate variability (HRV) in yoga practitioners. A total of 40 healthy male volunteers performed a working memory task, ‘n-back’, consisting of three levels of difficulty, 0-back, 1-back, and 2-back, separately, before and after three SYB sessions on different days. The SYB sessions included alternate nostril breathing (ANB), right nostril breathing (RNB), and breath awareness (BAW). Repeated measures analysis of variance showed a significant reduction in reaction time (ms) in 2-back condition immediately after ANB (−8%), RNB (−8%) and BAW (−5%) practices. Similarly, the accuracy was improved in the 0-back condition after RNB (4%), and in the 2-back condition after ANB (6%) and RNB (6%) practices. These results suggest that SYB practice enhances cognitive abilities (8–9%) related to memory load and improves the functioning of cardiac autonomic activity, which is required for the successful completion of mental tasks.Trial registered in the Clinical Trials Registry of India (CTRI/2018/01/011132).

Working memory dysfunction in fibromyalgia is associated with genotypes of the catechol- O-methyltransferase gene: an event-related potential study

Recent findings have associated different COMT genotypes with working memory capacity in patients with fibromyalgia. Although it is thought that the COMT gene may influence neural correlates (P2 and P3 ERP components) underlying working memory impairment in this chronic-pain syndrome, it has not yet been explored. Therefore, the aim of the present research was to investigate the potential effect of the COMT gene in fibromyalgia patients on ERP working memory indices (P2 and P3 components). For this purpose, 102 participants (51 patients and 51 healthy control participants) took part in the experiment. Event-related potentials and behavioral responses were recorded while participants performed a spatial n-back task. Participants had to decide if the stimulus coincided or not in the same location as the one presented one (1-back condition) or two (2-back condition) trials before. Genotypes of the COMT gene were determined through a saliva sample from all participants. Present results significantly showed lower working memory performance (p < 0.05) in patients with fibromyalgia as compared to control participants (higher rate of errors and slower reaction times). At neural level, we found that patients exhibited enhanced frontocentral and parieto-occipital P2 amplitudes compared to control participants (p < 0.05). Interestingly, we also observed that only fibromyalgia patients carrying the Val/Val genotype of the COMT gene showed higher frontocentral P2 amplitudes than control participants (p < 0.05). Current results (behavioral outcomes and P2 amplitudes) confirmed the presence of an alteration in working memory functioning in fibromyalgia. The enhancement of frontocentral P2 could be reflecting that these patients would manifest an inefficient way of activating executive attention processes, in carriers of the Val/Val genotype of COMT. To our knowledge, the present findings are the first linking neural indices of working memory dysfunctions and COMT genotypes in fibromyalgia. Applying a subgroup of patient’s strategy based on this genetic marker could be useful to establish more tailored therapeutical approaches.