N-back Research Articles

Correlation of muscle strength, working memory, and activities of daily living in older adults.

This study aims to investigate the relationship between muscle strength, working memory, and activities of daily living (ADL) in older adults. Additionally, it seeks to clarify the pathways and effects of working memory in mediating the relationship between muscle strength and ADL. Using a cross-sectional study design, we recruited 245 older adults individuals from nursing homes. We collected data on grip strength, the 30-s sit-to-stand test, the N-back task, and ADL. The data were analyzed using independent sample t-tests, χ2 tests, correlation analysis, and structural equation modeling. Grip strength significantly influenced ADL (effect size = -0.175, 95% CI: -0.226 to -0.124). Grip strength also had a significant direct effect on ADL (effect size = -0.114, 95% CI: -0.161 to -0.067). The 1-back task correct rate significantly mediated the relationship between grip strength and ADL (effect size = 0.054, 95% CI: -0.084 to -0.029). The 30-s sit-to-stand test significantly impacted ADL (effect size = -0.280, 95% CI: -0.358 to -0.203). It also had a significant direct effect on ADL (effect size = -0.095, 95% CI: -0.183 to -0.007). The 1-back task correct rate significantly mediated the relationship between the 30-s sit-to-stand test and ADL (effect size = -0.166, 95% CI: -0.236 to -0.106). There exists a strong correlation between muscle strength, working memory, and ADL. Increased muscle strength leads to better ADL performance and improved working memory tasks. Low cognitive load working memory tasks can mediate the relationship between muscle strength and ADL. Regular physical exercise can enhance muscle strength, slow down the decline of working memory, thereby maintaining or improving ADL in older adults.

Comparison of Working Memory Performance using Auditory N-back Task in Adults who do and do not Stutter

Abstract Introduction: Working memory is considered to be essential for higher-level cognition and phonological encoding. The N-back task is a popular test for evaluating working memory capacity. Phonological working memory which is involved in temporary storage and manipulation of information plays an important role in speech fluency. Previous investigations have revealed a reduced phonological working memory in English-speaking adults with stuttering (AWS). No studies to date have explored the role of phonological memory in Kannada-speaking AWS. The present study aimed to compare the working memory performance in auditory two back tasks between AWS and adults with no stuttering (AWNS). Methods: Participants included were 15 AWS (14 males and 1 female) and 16 AWNS (8 males and 8 females). The present study comprised of two tasks, namely auditory 2 back task for meaningful words (task 1) and auditory 2 back for nonwords (task 2). The participants performed two back tasks for the meaningful words and nonwords and were instructed to say “yes” whenever the same stimulus was heard 2 stimulus back and “no” for the different stimulus. Every accurate response received a score of 1, while an incorrect or no response received a score of 0. Results: The results revealed that AWS performed significantly poorer than AWNS in both tasks 1 and 2, which indicate that AWS has impaired working memory skills. Conclusion: The results of the present study indicated poorer performance of stutterers in auditory n-back test of phonological working memory. This shows that individuals with stuttering having an inadequate phonological working memory when compared to that of their counterparts. This could be due to their inaccurate phonological representations or attentional deficits.

Eye Movement Correlates of Working Memory Capacity: Evidence from the Reading Span Task

In reading, eye movements are typically influenced by both higher-level and lower-level cognitive processes that are affected by individual differences such as working memory capacity. However, the extent to which working memory impacts reading under increasing task demands remains uncertain. Therefore, this study aimed to explore the influence of working memory capacity, assessed via the n-back task, on peak saccade velocity during reading when an additional memory task is introduced. Thirty-one healthy participants with normal or corrected-to-normal vision read sentences performing either comprehension task or dual task on comprehension and working memory span. The results of the comprehension task were used as a baseline to track the differences in eye movement measures in the dual task with the increasing task demand. Participants who performed well in the n-back task exhibited higher peak saccade velocity during both single and dual reading tasks, particularly as the task demands increased: reading for comprehension while simultaneously maintaining six items in working memory was associated with the highest peak saccade velocity. Conversely, those with n-back lower performance did not display significant changes in peak saccade velocity. This discrepancy is attributed to task-induced variations in arousal among high-performing individuals. The study underscores the importance of individual differences in working memory and suggests a potential link between arousal and cognitive processes involved in reading comprehension.

Androgen deprivation increases frontopolar cortical thickness in prostate cancer patients: an effect of early neurodegeneration?

Androgen deprivation therapy (ADT) has been associated with adverse effects on the brain. ADT leads to altered testosterone levels that may affect brain morphology as well as cognition. Considering the reliability of cortical thickness (CT) as a marker of cognitive and brain changes, e.g., in Alzheimer's disease, we assessed the impacts of ADT on CT and working memory. Thirty men with non-metastatic prostate cancer receiving ADT and 32 patients not receiving ADT (controls or CON), matched in age and years of education, participated in N-back task and quality-of-life (QoL) assessments as well as brain imaging at baseline and prospectively at 6 months. Imaging data were processed with published routines to estimate CT and the results of a group by time flexible factorial analysis were evaluated at a corrected threshold. ADT and CON did not differ in N-back performance or QoL across time points. Relative to CON, patients receiving ADT showed significantly higher frontopolar cortex (FPC) CT at 6-month follow-up vs. baseline. Follow-up vs. baseline FPC CT change correlated negatively with changes in 2-back correct response rate and in testosterone levels across all participants. In mediation analysis, FPC CT change mediated the association between testosterone level change and 2-back accuracy rate change. Increases in FPC CT following 6 months of ADT may reflect early neurodegenerative changes in response to androgen deprivation. While no significant impact on working memory or QoL was observed over 6 months, further research of longer duration of treatment is warranted to unravel the full spectrum of cognitive and neural consequences of ADT in prostate cancer patients.

Influence of TMX2-CTNND1 polymorphism on cortical thickness in schizophrenia patients and unaffected siblings: an exploratory study based on target region sequencing.

The advancement of neuroimaging and genetic research has revealed the presence of morphological abnormalities and numerous risk genes, along with their associations. We aimed to estimate magnetic resonance imaging-derived cortical thickness across multiple brain regions. The cortical thickness of 129 schizophrenia patients, 42 of their unaffected siblings, and 112 healthy controls was measured and the candidate genes were sequenced. Comparisons were made of cortical thickness (including 68 regions of the Desikan-Killiany Atlas) and genetic variants (in 108 risk genes for schizophrenia) among the three groups, and correlation analyses were performed regarding cortical thickness, clinical symptoms, cognitive tests (such as the N-back task and the logical memory test), and genetic variants. Schizophrenia patients had significantly thinner bilateral frontal, temporal, and parietal gyri than healthy controls and unaffected siblings. Association analyses in target genes showed that four single nucleotide variants (SNVs) were significantly associated with schizophrenia, including thioredoxin-related transmembrane protein 2-catenin, cadherin-associated protein, delta 1 (SNV20673) (positive false discovery rate [PFDR] = 0.008) and centromere protein M (rs35542507, rs41277477, rs73165153) (PFDR = 0.030). Additionally, cortical thickness in the right pars triangularis was lower in carriers of the SNV20673 variant than in non-carriers (PFDR = 0.048). Finally, a positive correlation was found between right pars triangularis cortical thickness and logical memory in schizophrenia patients (r = 0.199, p = 0.032). This study identified regional morphological abnormalities in schizophrenia, including the right homologue of Broca's area, which was associated with a risk variant that affected delta-1 catenin and logical memory. These findings suggest a potential association between candidate gene loci, cortical thickness, and schizophrenia.

Relationship of Cognitive Function with Oxygenated Haemoglobin Concentration Difference Between the Left and Right Prefrontal Cortex During 40-Min Moderate-Intensity Exercise.

The high concentration of oxygenated haemoglobin (O2Hb) in the prefrontal cortex (PFC) during exercise improves cognitive performance. In this study, we aimed to elucidate the relationship of cognitive function with the O2Hb concentration difference between the left and right PFC (L-PFC and R-PFC, respectively) during sustained exercise. We enrolled 12 healthy adult males who, after a 4-min rest and warm-up, performed a 40-min exercise regime at a workload corresponding to 50% maximal oxygen consumption. A 2-back task was performed, and the reaction times (RTs) were recorded before exercise, immediately after exercise, and 20 min after exercise. Near-infrared spectroscopy was used to monitor L-PFC and R-PFC. RT was shortened immediately and 20 min after exercise, and O2Hb concentration difference between L-PFC and R-PFC positively correlated with RT 20 min after exercise. These findings suggest that 40-min exercise induced a phenomenon of neural compensation.

Local variation in brain temperature explains gender-specificity of working memory performance.

Exploring gender differences in cognitive abilities offers vital insights into human brain functioning. Our study utilized advanced techniques like magnetic resonance thermometry, standard working memory n-back tasks, and functional MRI to investigate if gender-based variations in brain temperature correlate with distinct neuronal responses and working memory capabilities. We observed a significant decrease in average brain temperature in males during working memory tasks, a phenomenon not seen in females. Although changes in female brain temperature were significantly lower than in males, we found an inverse relationship between the absolute temperature change (ATC) and cognitive performance, alongside a correlation with blood oxygen level dependent (BOLD) signal change induced by neural activity. This suggests that in females, ATC is a crucial determinant for the link between cognitive performance and BOLD responses, a linkage not evident in males. However, we also observed additional female specific BOLD responses aligned with comparable task performance to that of males. Our results suggest that females compensate for their brain's heightened temperature sensitivity by activating additional neuronal networks to support working memory. This study not only underscores the complexity of gender differences in cognitive processing but also opens new avenues for understanding how temperature fluctuations influence brain functionality.

Comparative Effects of Cognitive Rehabilitation and Photobiomodulation on Drug Craving in Treatment-Seeking Opioid Addicts.

Background: Drug addiction refers to a maladaptive pattern of drug use that frequently leads to substance abuse problems and accompanying cognitive and behavioral symptoms. Among the crucial criteria of drug addiction, craving stands out as a potent factor contributing to ongoing drug abuse and relapse following period of abstinence. To date, there is no definitive method for eradicating opioid cravings. The introduction of novel neurocognitive interventions, such as cognitive rehabilitation and photobiomodulation (PBM), into the realm of psychiatric treatments holds promise due to the parallels between drug addiction and other psychiatric disorders. These innovative techniques offer potential value in addressing drug addiction. Objective: This study aimed to assess and compare the efficacy of cognitive rehabilitation and PBM in alleviating drug cravings among individuals undergoing addiction treatment in clinical settings. Methods: The research used randomized clinical trial as the chosen research method. The statistical population encompassed all clients receiving treatment for addiction at clinics, selected through the convenience sampling method, with α = 0.05 significance level and an effect size of 85%. Gpower software was utilized to determine three equal groups. Sixty-three participants, each having a mean total score higher than 3 out of 5 on the Desire for Drug Questionnaire (DDQ), were randomly assigned to two experimental groups (n = 21 each) and a control group (n = 21). For the assessment of immediate and periodic opioid craving, the DDQ and the Obsessive Compulsive Drug Use Scale were used. In the low-level laser group, an 810 nm wavelength with continuous irradiation was applied twice a week at a distance of 1 cm by 1 cm to the prefrontal part of the brain for duration of 6 weeks (12 sessions). In the brain rehabilitation group, the stop signal and n-back tasks software were used twice a week for period of 6 weeks (comprising 12 sessions, each lasting 30 min). Results: The results demonstrated that each intervention significantly reduced drug craving in both the post-test and follow-up phases compared to the control group. The Bonferroni post hoc test indicated that PBM was more effective than cognitive rehabilitation in terms of working memory (WM) and inhibitory control for reducing drug craving (p < 0.05). Conclusions: While both PBM and cognitive rehabilitation targeting WM and inhibitory control effectively reduced opioid drug craving, low-level laser therapy proved to be more effective than cognitive rehabilitation in this regard.

Heart rate response to cognitive load as a marker of depression and increased anxiety.

Understanding the interplay between cardiovascular parameters, cognitive stress induced by increasing load, and mental well-being is vital for the development of integrated health strategies today. By monitoring physiological signals like electrocardiogram (ECG) and photoplethysmogram (PPG) in real time, researchers can discover how cognitive tasks influence both cardiovascular and mental health. Cardiac biomarkers resulting from cognitive strain act as indicators of autonomic nervous system function, potentially reflecting conditions related to heart and mental health, including depression and anxiety. The purpose of this study is to investigate how cognitive load affects ECG and PPG measurements and whether these can signal early cardiovascular changes during depression and anxiety disorders. Ninety participants aged 18 to 45 years, ranging from symptom-free individuals to those with diverse psychological conditions, were assessed using psychological questionnaires and anamnesis. ECG and PPG monitoring were conducted as volunteers engaged in a cognitive 1-back task consisting of two separate blocks, each with six progressively challenging levels. The participants' responses were analyzed to correlate physiological and psychological data with cognitive stressors and outcomes. The study confirmed a notable interdependence between anxiety and depression, and cardiovascular responses. Task accuracy decreased with increased task difficulty. A strong relationship between PPG-measured heart rate and markers of depression and trait anxiety was observed. Increasing task difficulty corresponded to an increase in heart rate, linked with elevated levels of depression and trait anxiety. A strong relationship between ECG-measured heart rate and anxiety attacks was observed. Increasing task difficulty corresponded to an increase in heart rate, linked with elevated levels of anxiety attacks, although this association decreased under more challenging conditions. The findings underscore the predictive importance of ECG and PPG heart rate parameters in mental health assessment, particularly depression and anxiety under cognitive stress induced by increasing load. We discuss mechanisms of sympathetic activation explaining these differences. Our research outcomes have implications for clinical assessments and wearable device algorithms for more precise, personalized mental health diagnostics.

Cognitive Mechanisms Underlying Sports Performance of Athletes Engaged in Strategic Team Sports

We examined the cognitive performance of athletes engaged in strategic team sports such as football and basketball with sixty participants including athletes with at least five years of experience at National/State level in football and basketball and non-athletes. Measures of vigilance (continuous performance task), selective attention (spatial cuing task), visual search (feature and conjunction search task), attention network task, working memory (n-back task) and motion perception (apparent motion task) were employed. Athletes outperformed non- athletes on measures of vigilance, visual search, selective attention, and motion perception as they need to process multiple stimuli and engage in coordinated actions. Compared to football players, basketball players performed better with respect to vigilance, attentional facilitation and shifting; and faster target detection in conjunction search task with higher set-size. This is explained in terms of the need to assess the diverse environment and dynamically respond to the requirements related to movement sequences. Basketball and football players were comparable to non-athletes on the working memory task. Football players showed better performance on motion perception task compared to basketball players by effectively varying the temporal distance between stimuli for a strong motion percept, which may account for their ability to judge the speed of motion helping them to accurately perceive other’s actions to prepare for their own action. Thus, different strategic team sports may involve different cognitive skills mediating sports performance. Future work needs to explore more about sport- specific cognitive-perceptual expertise in athletes engaged in team sports as a function of training and experience using a longitudinal design.

Cerebral response to emotional working memory based on vocal cues: an fNIRS study.

Humans mainly utilize visual and auditory information as a cue to infer others' emotions. Previous neuroimaging studies have shown the neural basis of memory processing based on facial expression, but few studies have examined it based on vocal cues. Thus, we aimed to investigate brain regions associated with emotional judgment based on vocal cues using an N-back task paradigm. Thirty participants performed N-back tasks requiring them to judge emotion or gender from voices that contained both emotion and gender information. During these tasks, cerebral hemodynamic response was measured using functional near-infrared spectroscopy (fNIRS). The results revealed that during the Emotion 2-back task there was significant activation in the frontal area, including the right precentral and inferior frontal gyri, possibly reflecting the function of an attentional network with auditory top-down processing. In addition, there was significant activation in the ventrolateral prefrontal cortex, which is known to be a major part of the working memory center. These results suggest that, compared to judging the gender of voice stimuli, when judging emotional information, attention is directed more deeply and demands for higher-order cognition, including working memory, are greater. We have revealed for the first time the specific neural basis for emotional judgments based on vocal cues compared to that for gender judgments based on vocal cues.

Relationship between Working Memory, Retrospective Memory and Strategic Monitoring with Prospective Memory Performance

Working memory is one of the significant factors that can influence prospective memory. Prospective memory inherently encompasses elements of retrospective memory, and strategic monitoring also affects performance. Therefore, the study investigates the relationship between strategic monitoring, retrospective memory, working memory, and prospective memory. The study involved 120 participants (60 females and 60 males). The Beck Depression Inventory, n-Back tasks, and Virtual Week tasks were administered to the participants. According to the findings, working memory performance predicts prospective memory (β= .30; p

Effects of the special olympics unified sports soccer training program on executive function in adolescents with intellectual disabilities

ObjectiveExecutive dysfunction is common in in individuals with intellectual disability (ID). This study examined the effects of the Special Olympics Unified Sports (UNS) soccer program on executive function (EF) and prefrontal cortex activation in ID adolescents. MethodsFunctional near-infrared spectroscopy (fNIRS) was utilized to compare EF between a group participating in UNS soccer training (n = 18) and a control group (n = 26) in the flanker task, 2-back task, and dots–triangles task. ResultsThe results revealed that the soccer group performed significantly better in the dots-triangles and 2-back tasks than the control group. However, it is unclear whethersoccer training may improve activation of R-DLPFC during performance of the dotstriangles task. In the 2-back task, activation in the right frontopolar area (R-FPA) was lower in the soccer group when compared to the control group. Notably, no significant differences were observed in the flanker task ConclusionIn conclusion, UNS soccer training may positively affect working memory in adolescents with intellectual disabilities by improving activation of RFA, but whether it activates R-VLPFC is uncertain. These results indicate that the UNS soccer trainingprogram holds promise for enhancing executive function in adolescents with ID, and improving the quality of life in this population.

Impaired Neurovascular Coupling and Increased Functional Connectivity in the Frontal Cortex Predict Age-Related Cognitive Dysfunction.

Impaired cerebrovascular function contributes to the genesis of age-related cognitive decline. In this study, the hypothesis is tested that impairments in neurovascular coupling (NVC) responses and brain network function predict cognitive dysfunction in older adults. Cerebromicrovascular and working memory function of healthy young (n = 21, 33.2±7.0 years) and aged (n = 30, 75.9±6.9 years) participants are assessed.To determine NVC responses and functional connectivity (FC) during a working memory (n-back) paradigm, oxy- and deoxyhemoglobin concentration changes from the frontal cortex using functional near-infrared spectroscopy are recorded. NVC responses are significantly impaired during the 2-back task in aged participants, while the frontal networks are characterized by higher local and global connection strength, and dynamic FC (p < 0.05). Both impaired NVC and increased FC correlate with age-related decline in accuracy during the 2-back task. These findings suggest that task-related brain states in older adults require stronger functional connections to compensate for the attenuated NVC responses associated with working memory load.

Mental workload classification using convolutional neural networks based on fNIRS-derived prefrontal activity

BackgroundFunctional near-infrared spectroscopy (fNIRS) is a tool to assess brain activity during cognitive testing. Despite its usefulness, its feasibility in assessing mental workload remains unclear. This study was to investigate the potential use of convolutional neural networks (CNNs) based on functional near-infrared spectroscopy (fNIRS)-derived signals to classify mental workload in individuals with mild cognitive impairment.MethodsSpatial images by constructing a statistical activation map from the prefrontal activity of 120 subjects with MCI performing three difficulty levels of the N-back task (0, 1, and 2-back) were used for CNNs. The CNNs were evaluated using a 5 and 10-fold cross-validation method.ResultsAs the difficulty level of the N-back task increased, the accuracy decreased and prefrontal activity increased. In addition, there was a significant difference in the accuracy and prefrontal activity across the three levels (p’s < 0.05). The accuracy of the CNNs based on fNIRS-derived spatial images evaluated by 5 and 10-fold cross-validation in classifying the difficulty levels ranged from 0.83 to 0.96.ConclusionfNIRS could also be a promising tool for measuring mental workload in older adults with MCI despite their cognitive decline. In addition, this study demonstrated the feasibility of the classification performance of the CNNs based on fNIRS-derived signals from the prefrontal cortex.

Correlates of physical activity levels, muscle strength, working memory, and cognitive function in older adults.

To explore the relationship between physical activity level, muscle strength, working memory and cognitive function in older adults. A cross-sectional research design was employed to recruit 120 older adults individuals aged 70 and above. Participants were asked to complete the International Physical Activity Questionnaire-Short Form and the Montreal Cognitive Assessment Scale. Data on variables such as grip strength and performance on the N-back task were collected. Data analysis involved the use of independent samples t-tests, χ2 tests, linear regression analysis, Pearson correlation analysis, and one-way analysis of variance (ANOVA). The detection rate of cognitive dysfunction in older adults was 53.211%; 1-back correct rate had an explanatory power of 11.6% for the cognitive function scores of older adults (R2 = 0.116, p < 0.001); grip strength showed a significant positive correlation with 1-back correct rate (r = 0.417, p < 0.001), and was significantly correlated with the 0-back response time (r = -0.478), 1 -back response time (r = -0.441) were significantly negatively correlated (p < 0.001); physical activity level was significantly positively correlated with grip strength (r = 0.559, p < 0.001), and the difference in grip strength among older adults with different physical activity levels was statistically significant (F = 19.685, p < 0.001). Physical activity level, muscle strength, working memory, and cognitive function are closely related in older adults, and the relational pathway of physical activity → muscle strength → working memory → cognitive function may serve as a useful addition to promote the field of cognitive research in older adults. To identify and prevent cognitive decline in older adults, physical activity questionnaires, grip strength tests, and 1-back task tests can be extended to nursing homes and communities.

Distinct age-related brain activity patterns in the prefrontal cortex when increasing cognitive load: A functional near-infrared spectroscopy study

Researchers have long observed distinct brain activity patterns in older adults compared with younger adults that correlate with cognitive performance. Mainly, older adults tend to show over-recruitment of bilateral brain regions during lower task loads and improved performance interpreted as compensation, but not observed at higher loads. However, there are discrepancies about whether increases in activity are compensatory and whether older adults can show compensation at higher loads. Our aim was to examine age-related differences in prefrontal cortex (PFC) activity and cognitive performance using functional near-infrared spectroscopy (fNIRS) during single and dual N-back tasks. Twenty-seven young adults (18–27 years) and 31 older adults (64–84 yrs) took part in the study. We used a robust fNIRS data methodology consisting of channel and region of interest analyses. Results showed differences in performance between task load conditions and age-related differences in reaction times but no age-group effects for accuracy. Older adults exhibited more bilateral PFC activation compared with young adults across all tasks and showed increases in brain activity in high compared to low load conditions. Our findings further support previous reports showing that older adults use compensatory recruitment of additional brain regions in PFC to maintain cognitive performance but go against the notion that such compensation is not present at higher cognitive loads. Additionally, our results indicate that fNIRS is a sensitive tool that can characterize adaptive cortical changes in healthy aging.

The Association between Working Hours with Vigilance and Executive Function of Intensive Care Unit Nurses

Background. Vigilance and executive functions are integral to nursing practice. Prolonged working hours are associated with heightened fatigue and increased nursing errors. However, the impact of work duration on the vigilance and executive function of ICU nurses remains unexplored. Objective. This study aims to elucidate the association between ICU nurses’ working hours, vigilance, and executive function. Design. A cross-sectional study. Setting. Intensive care medicine department of a tertiary hospital in Zhengzhou, China. Participants. A total of 51 registered nurses who participated in 12 h shifts in the ICU completed the survey. Methods. E-prime software was employed to develop four test tasks to measure the vigilance and executive functioning of ICU nurses. The test was performed before the start of the shift and after 4, 8, and 12 h. Results. The analysis revealed no statistically significant differences in the response time of vigilance for ICU nurses across shifts ( p = 0.503 ) or working hours ( p = 0.078 ). However, a significant difference existed in lapses across working hours ( p = 0.005 ), significantly increasing after 8 and 12 h. The analysis indicated a significant difference in Flanker effect size across different working hours ( p = 0.035 ). The analysis revealed no significant differences in the switch cost ( p = 0.200 ) or response accuracy ( p = 0.479 ) of the task switching across working hours. The response accuracy for the 2-back task differed significantly ( p = 0.003 ) across working hours. Conclusion. Limited evidence demonstrated that vigilance and specific aspects of executive functioning (inhibitory control and working memory) of ICU nurses were negatively correlated with the duration of their work in a real clinical setting. Furthermore, no vigilance and executive function differences were identified between day and night shifts. Implications for Nursing Management. Nursing administrators should reconsider scheduling 12 h shifts, shortening shifts, or implementing short rest periods to reduce fatigue and cognitive load. In addition, flexible scheduling and rationalizing the order of work may help reduce the possible risks associated with prolonged work.

Evidence for modulation of EEG microstates by mental workload levels and task types.

Electroencephalography (EEG) microstate analysis has become a popular tool for studying the spatial and temporal dynamics of large-scale electrophysiological activities in the brain in recent years. Four canonical topographies of the electric field (classes A, B, C, and D) have been widely identified, and changes in microstate parameters are associated with several psychiatric disorders and cognitive functions. Recent studies have reported the modulation of EEG microstate by mental workload (MWL). However, the common practice of evaluating MWL is in a specific task. Whether the modulation of microstate by MWL is consistent across different types of tasks is still not clear. Here, we studied the topographies and dynamics of microstate in two independent MWL tasks: NBack and the multi-attribute task battery (MATB) and showed that the modulation of MWL on microstate topographies and parameters depended on tasks. We found that the parameters of microstates A and C, and the topographies of microstates A, B, and D were significantly different between the two tasks. Meanwhile, all four microstate topographies and parameters of microstates A and C were different during the NBack task, but no significant difference was found during the MATB task. Furthermore, we employed a support vector machine recursive feature elimination procedure to investigate whether microstate parameters were suitable for MWL classification. An averaged classification accuracy of 87% for within-task and 78% for cross-task MWL discrimination was achieved with at least 10 features. Collectively, our findings suggest that topographies and parameters of microstates can provide valuable information about neural activity patterns with a dynamic temporal structure at different levels of MWL, but the modulation of MWL depends on tasks and their corresponding functional systems. Moreover, as a potential indicator, microstate parameters could be used to distinguish MWL.

MST-net: A multi-scale swin transformer network for EEG-based cognitive load assessment

Cognitive load assessment plays a crucial role in monitoring safe production, resource allocation, and subjective initiative in human-computer interaction. Due to its high time resolution and convenient acquisition, Electroencephalography (EEG) is widely applied in brain monitoring and cognitive state assessment. In this study, a multi-scale Swin Transformer network (MST-Net) was proposed for cognitive load assessment, which extracts local features with different sensory fields using a multi-scale parallel convolution model and introduces the attention mechanism of the Swin Transformer to obtain the feature correlations among multi-scale local features. The performance of the proposed network was validated using the EEG signals collected during cognitive tasks and N-back tasks with three different load levels. Results show that the MST-Net network achieved the best classification accuracy on both local and public datasets, and was higher than the mainstream Swin Transformer and CNN. Furthermore, results of ablation experiments and feature visualization revealed that the proposed MST-Net could well characterize different cognitive loads, which not only provided novel and powerful tools for cognitive load assessment but also showed potential for broad application in brain-computer interface (BCI) systems.