Neurophysiological signals of working memory in normal aging

Modulating prefrontal cortex activity to alleviate stress-induced working memory deficits: A transcranial direct current (tDCS) study

This study explores the impact of stress on working memory (WM) performance, and the potential mitigating effects of transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (dlPFC) and ventromedial prefrontal cortex (vmPFC). The study had a mixed, randomized, single-blind, sham-controlled design, with stress induction as within-subject and stimulation condition as between-subject factors. We assessed stress-induced WM deficits using aversive video clips to induce stress and a verbal n-back task to assess WM performance. We analyzed physiological (cortisol and heart rate), behavioral, and electroencephalographic (EEG) changes due to stress before, during, and after WM task performance and their modulation by tDCS. Stress impaired WM performance in the sham stimulation condition for the 3-back load, but not for 2-back or 4-back loads in the WM task and was associated with elevated physiological stress markers. tDCS over the vmPFC led to better WM task performance while stimulation over the dlPFC did not. Active tDCS with both dlPFC and vmPFC stimulation blunted cortisol release in stress conditions compared to sham. The EEG analysis revealed potential mechanisms explaining the behavioral effects of vmPFC stimulation. vmPFC stimulation led to a decreased P200 event-related potential (ERP) component compared to the sham stimulation condition and resulted in higher task-related alpha desynchronization, indicating reduced distractions and better focus during task performance. This study thus shows that the vmPFC might be a potential target for mitigating the effects of stress on WM performance and contributes to the development of targeted interventions for stress-related cognitive impairments.

Neural decoding reveals dynamic patterns of visual chunk memory processes

Chunk memory constitutes the basic unit that manages long-term memory and converts it into immediate decision-making processes, it remains unclear how to interpret and organize incoming information to form effective chunk memory. This paper investigates electroencephalography (EEG) patterns from the perspective of time-domain feature extraction using chunk memory in visual statistical learning and combines time-resolved multivariate pattern analysis (MVPA). The GFP and MVPA results revealed that chunk memory processes occurred during specific time windows in the learning phase. These processes included attention modulation (P1), recognition and feature extraction (P2), and segmentation for long-term memory conversion (P6). In the decision-making stage, chunk memory processes were encoded by four ERP components. Scene processing correlated with P1, followed by feature extraction facilitated by P2, encoding process (P4), and segmentation process (P6). This paper identifies the early process of chunk memory through implicit learning and applies univariate and multivariate approaches to establish the neural activity patterns of the early chunk memory process, which provides ideas for subsequent related studies.

Brain computer interfaces for cognitive enhancement in older people - challenges and applications: a systematic review

BACKGROUND

Brain-computer interface (BCI) offers promising solutions to cognitive enhancement in older people. Despite the clear progress received, there is limited evidence of BCI implementation for rehabilitation. This systematic review addresses BCI applications and challenges in the standard practice of EEG-based neurofeedback (NF) training in healthy older people or older people with mild cognitive impairment (MCI).

METHODS

Articles were searched via MEDLINE, PubMed, SCOPUS, SpringerLink, and Web of Science. 16 studies between 1st January 2010 to 1st November 2024 are included after screening using PRISMA. The risk of bias, system design, and neurofeedback protocols are reviewed.

RESULTS

The successful BCI applications in NF trials in older people were biased by the randomisation process and outcome measurement. Although the studies demonstrate promising results in effectiveness of research-grade BCI for cognitive enhancement in older people, it is premature to make definitive claims about widespread BCI usability and applicability.

SIGNIFICANCE

This review highlights the common issues in the field of EEG-based BCI for older people. Future BCI research could focus on trial design and BCI performance gaps between the old and the young to develop a robust BCI system that compensates for age-related declines in cognitive and motor functions.

Connectivity changes in two-channel prefrontal ERP associated with early cognitive decline in the elderly population: beta band responses to the auditory oddball stimuli

Background

This study utilized recent advancements in electroencephalography (EEG) technology that enable the measurement of prefrontal event-related potentials (ERPs) to facilitate the early detection of mild cognitive impairment (MCI). We investigated two-channel prefrontal ERP signals obtained from a large cohort of elderly participants and compare among cognitively normal (CN), subjective cognitive decline (SCD), amnestic MCI (aMCI), and nonamnestic MCI (naMCI) groups.

Methods

Signal processing and ERP component analyses, specifically adapted for two-channel prefrontal ERP signals evoked by the auditory oddball task, were performed on a total of 1,754 elderly participants. Connectivity analyses were conducted to assess brain synchronization, especially in the beta band involving the phase locking value (PLV) and coherence (COH). Time-frequency, time-trial, grand average, and further statistical analyses of the standard and target epochs were also conducted to explore differences among the cognition groups.

Results

The MCI group's response to target stimuli was characterized by greater response time variability (p < 0.001) and greater variability in the P300 latency (p < 0.05), leading to less consistent responses than those of the healthy control (HC) group (CN+SCD subgroups). In the connectivity analyses of PLV and COH waveforms, significant differences were observed, indicating a loss of synchronization in the beta band in response to standard stimuli in the MCI group. In addition, the absence of event-related desynchronization (ERD) indicated that information processing related to readiness and task performance in the beta band was not efficient in the MCI group. Furthermore, the observed decline in the P200 amplitude as the standard trials progressed suggests the impaired attention and inhibitory processes in the MCI group compared to the HC group. The aMCI subgroup showed high variability in COH values, while the naMCI subgroup showed impairments in their overall behavioral performance.

Conclusion

These findings highlight the variability and connectivity measures can be used as markers of early cognitive decline; such measures can be assessed with simple and fast two-channel prefrontal ERP signals evoked by both standard and target stimuli. Our study provides deeper insight of cognitive impairment and the potential use of the prefrontal ERP connectivity measures to assess early cognitive decline.

Complexity measures reveal age-dependent changes in electroencephalogram during working memory task

The alterations in electroencephalogram (EEG) signals are the complex outputs of functional factors, such as normal physiological aging, pathological process, which results in further cognitive decline. It is not clear that when brain aging initiates, but elderly people are vulnerable to be incipient of neurodegenerative diseases such as Alzheimer's disease. The EEG signals were recorded from 20 healthy middle age and 20 healthy elderly subjects while performing a working memory task. Higuchi's fractal dimension (HFD), Katz's fractal dimension (KFD), sample entropy and three Hjorth parameters were extracted to analyse the complexity of EEG signals. Four machine learning classifiers, multilayer perceptron (MLP), support vector machine (SVM), K-nearest neighbour (KNN), and logistic model tree (LMT) were employed to distinguish the EEG signals of middle age and elderly age groups. HFD, KFD and Hjorth complexity were found significantly correlated with age. MLP achieved the highest overall accuracy of 93.75%. For posterior region, the maximum accuracy of 92.50% was achieved using MLP. Since fractal dimension associated with the complexity of EEG signals, HFD, KFD and Hjorth complexity demonstrated the decreased complexity from middle age to elderly groups. The complexity features appear to be more appropriate indicators of monitoring EEG signal complexity in healthy aging.

Modern neurophysiological techniques indexing normal or abnormal brain aging

Brain aging is associated with a decline in cognitive performance, motor function and sensory perception, even in the absence of neurodegeneration. The underlying pathophysiological mechanisms remain incompletely understood, though alterations in neurogenesis, neuronal senescence and synaptic plasticity are implicated. Recent years have seen advancements in neurophysiological techniques such as electroencephalography (EEG), magnetoencephalography (MEG), event-related potentials (ERP) and transcranial magnetic stimulation (TMS), offering insights into physiological and pathological brain aging. These methods provide real-time information on brain activity, connectivity and network dynamics. Integration of Artificial Intelligence (AI) techniques promise as a tool enhancing the diagnosis and prognosis of age-related cognitive decline. Our review highlights recent advances in these electrophysiological techniques (focusing on EEG, ERP, TMS and TMS-EEG methodologies) and their application in physiological and pathological brain aging. Physiological aging is characterized by changes in EEG spectral power and connectivity, ERP and TMS parameters, indicating alterations in neural activity and network function. Pathological aging, such as in Alzheimer's disease, is associated with further disruptions in EEG rhythms, ERP components and TMS measures, reflecting underlying neurodegenerative processes. Machine learning approaches show promise in classifying cognitive impairment and predicting disease progression. Standardization of neurophysiological methods and integration with other modalities are crucial for a comprehensive understanding of brain aging and neurodegenerative disorders. Advanced network analysis techniques and AI methods hold potential for enhancing diagnostic accuracy and deepening insights into age-related brain changes.

Neurophysiological and other features of working memory in older adults at risk for dementia

Theta-gamma coupling (TGC) is a neurophysiological process that supports working memory. Working memory is associated with other clinical and biological features. The extent to which TGC is associated with these other features and whether it contributes to working memory beyond these features is unknown. Two-hundred-and-three older participants at risk for Alzheimer's dementia-98 with mild cognitive impairment (MCI), 39 with major depressive disorder (MDD) in remission, and 66 with MCI and MDD (MCI + MDD)-completed a clinical assessment, N-back-EEG, and brain MRI. Among them, 190 completed genetic testing, and 121 completed [11C] Pittsburgh Compound B ([11C] PIB) PET imaging. Hierarchical linear regressions were used to assess whether TGC is associated with demographic and clinical variables; Alzheimer's disease-related features (APOE ε4 carrier status and β-amyloid load); and structural features related to working memory. Then, linear regressions were used to assess whether TGC is associated with 2-back performance after accounting for these features. Other than age, TGC was not associated with any non-neurophysiological features. In contrast, TGC (β = 0.27; p = 0.006), age (β = - 0.29; p = 0.012), and parietal cortical thickness (β = 0.24; p = 0.020) were associated with 2-back performance. We also examined two other EEG features that are linked to working memory-theta event-related synchronization and alpha event-related desynchronization-and found them not to be associated with any feature or performance after accounting for TGC. Our findings suggest that TGC is a process that is independent of other clinical, genetic, neurochemical, and structural variables, and supports working memory in older adults at risk for dementia.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11571-023-09938-y.

Long-term findings on working memory neural dynamics in healthcare workers after mild COVID-19

OBJECTIVE

Understanding the long-term impact of Coronavirus Disease 2019 (COVID-19) on cognitive function, even in mild cases, is critical to the well-being of individuals, especially for healthcare workers who are at increased risk of exposure to the virus. To the best of our knowledge, the electrophysiological activity underlying cognitive functioning has not yet been explored.

METHODS

Seventy-seven healthcare workers took part in the study (43 with mild infection about one year before the study and 34 uninfected). To assess cognitive status, event-related potentials (ERPs) and behavioural responses were recorded while participants performed a working memory task.

RESULTS

COVID-19 participants exhibited a distinct neural pattern with lower parieto-occipital N1 amplitudes and higher frontal P2 amplitudes as compared to non-infected healthcare workers. We found no behavioural differences (reaction times and error rates) in working memory functioning between groups.

CONCLUSIONS

This neural pattern suggests the presence of a decrement of processing resources linked to the encoding of sensory information (N1), followed by the enhanced of the P2 response which could be interpreted as the activation of compensation mechanism in COVID-19 participants.

SIGNIFICANCE

The current findings point out that ERPs could serve as valuable neural indices for detecting distinctive patterns in working memory functioning of COVID-19 participants, even in mild cases. However, further research is required to precisely ascertain the long-term cognitive effects of COVID-19 beyond one-year post-infection.

Lower individual alpha frequency in individuals with chronic low back pain and fear of movement

ABSTRACT

Significant progress has been made in linking measures of individual alpha frequency (IAF) and pain. A lower IAF has been associated with chronic neuropathic pain and with an increased sensitivity to pain in healthy young adults. However, the translation of these findings to chronic low back pain (cLBP) are sparse and inconsistent. To address this limitation, we assessed IAFs in a cohort of 70 individuals with cLBP, implemented 3 different IAF calculations, and separated cLBP subjects based on psychological variables. We hypothesized that a higher fear movement in cLBP is associated with a lower IAF at rest. A total of 10 minutes of resting data were collected from 128 electroencephalography channels. Our results offer 3 novel contributions to the literature. First, the high fear group had a significantly lower peak alpha frequency. The high fear group also reported higher pain and higher disability. Second, we calculated individual alpha frequency using 3 different but established methods; the effect of fear on individual alpha frequency was robust across all methods. Third, fear of movement, pain intensity, and disability highly correlated with each other and together significantly predicted IAF. Our findings are the first to show that individuals with cLBP and high fear have a lower peak alpha frequency.

Magnetoencephalography-derived oscillatory microstate patterns across lifespan: the Cambridge centre for ageing and neuroscience cohort

The aging brain represents the primary risk factor for many neurodegenerative disorders. Whole-brain oscillations may contribute novel early biomarkers of aging. Here, we investigated the dynamic oscillatory neural activities across lifespan (from 18 to 88 years) using resting Magnetoencephalography (MEG) in a large cohort of 624 individuals. Our aim was to examine the patterns of oscillation microstates during the aging process. By using a machine-learning algorithm, we identify four typical clusters of microstate patterns across different age groups and different frequency bands: left-to-right topographic MS1, right-to-left topographic MS2, anterior-posterior MS3 and fronto-central MS4. We observed a decreased alpha duration and an increased alpha occurrence for sensory-related microstate patterns (MS1 & MS2). Accordingly, theta and beta changes from MS1 & MS2 may be related to motor decline that increased with age. Furthermore, voluntary 'top-down' saliency/attention networks may be reflected by the increased MS3 & MS4 alpha occurrence and complementary beta activities. The findings of this study advance our knowledge of how the aging brain shows dysfunctions in neural state transitions. By leveraging the identified microstate patterns, this study provides new insights into predicting healthy aging and the potential neuropsychiatric cognitive decline.

Compensatory brain activity pattern is not present in older adults during the n-back task performance-Findings based on EEG frequency analysis

Introduction

Cognitive ability is one of the most important enablers for successful aging. At the same time, cognitive decline is a well-documented phenomenon accompanying the aging process. Nevertheless, it is acknowledged that aging can also be related to positive processes that allow one to compensate for the decline. These processes include the compensatory brain activity of older adults primarily investigated using fMRI and PET. To strengthen the cognitive interpretation of compensatory brain activity in older adults, we searched for its indicators in brain activity measured by EEG.

Methods

The study sample comprised 110 volunteers, including 50 older adults (60-75 years old) and 60 young adults (20-35 years old) who performed 1-back, 2-back, and 3-back tasks while recording the EEG signal. The study analyzed (1) the level of cognitive performance, including sensitivity index, the percentage of correct answers to the target, and the percentage of false alarm errors; (2) theta and alpha power for electrodes located in the frontal-midline (Fz, AF3, AF4, F3, F4, FC1, and FC2) and the centro-parietal (CP1, CP2, P3, P4, and Pz) areas.

Results

Cognitive performance was worse in older adults than in young adults, which manifested in a significantly lower sensitivity index and a significantly higher false alarm error rate at all levels of the n-back task difficulty. Simultaneously, performance worsened with increasing task difficulty regardless of age. Significantly lower theta power in the older participants was observed at all difficulty levels, even at the lowest one, where compensatory activity was expected. At the same time, at this difficulty level, cognitive performance was worse in older adults than in young adults, which could reduce the chances of observing compensatory brain activity. The significant decrease in theta power observed in both age groups with rising task difficulty can reflect a declining capacity for efficient cognitive functioning under increasing demands rather than adapting to this increase. Moreover, in young adults, alpha power decreased to some extent with increasing cognitive demand, reflecting adaptation to them, while in older adults, no analogous pattern was observed.

Discussion

In conclusion, based on the results of the current study, the presence of compensatory activity in older adults cannot be inferred.

Event-related theta and gamma band oscillatory dynamics during visuo-spatial sequence memory in younger and older adults

Visuo-spatial working memory (VSWM) for sequences is thought to be crucial for daily behaviors. Decades of research indicate that oscillations in the gamma and theta bands play important functional roles in the support of visuo-spatial working memory, but the vast majority of that research emphasizes measures of neural activity during memory retention. The primary aims of the present study were (1) to determine whether oscillatory dynamics in the Theta and Gamma ranges would reflect item-level sequence encoding during a computerized spatial span task, (2) to determine whether item-level sequence recall is also related to these neural oscillations, and (3) to determine the nature of potential changes to these processes in healthy cognitive aging. Results indicate that VSWM sequence encoding is related to later (∼700 ms) gamma band oscillatory dynamics and may be preserved in healthy older adults; high gamma power over midline frontal and posterior sites increased monotonically as items were added to the spatial sequence in both age groups. Item-level oscillatory dynamics during the recall of VSWM sequences were related only to theta-gamma phase amplitude coupling (PAC), which increased monotonically with serial position in both age groups. Results suggest that, despite a general decrease in frontal theta power during VSWM sequence recall in older adults, gamma band dynamics during encoding and theta-gamma PAC during retrieval play unique roles in VSWM and that the processes they reflect may be spared in healthy aging.

Exploring the impact of intensified multiple session tDCS over the left DLPFC on brain function in MCI: a randomized control trial

Transcranial direct current stimulation combined with cognitive training (tDCS-cog) represents a promising approach to combat cognitive decline among healthy older adults and patients with mild cognitive impairment (MCI). In this 5-day-long double-blinded randomized trial, we investigated the impact of intensified tDCS-cog protocol involving two trains of stimulation per day on working memory (WM) enhancement in 35 amnestic and multidomain amnestic MCI patients. Specifically, we focused to improve WM tasks relying on top-down attentional control and hypothesized that intensified tDCS would enhance performance of visual object matching task (VOMT) immediately after the stimulation regimen and at a 1-month follow-up. Secondarily, we explored whether the stimulation would augment online visual working memory training. Using fMRI, we aimed to elucidate the neural mechanisms underlying the intervention effects by analyzing BOLD activations during VOMT. Our main finding revealed no superior after-effects of tDCS-cog over the sham on VOMT among individuals with MCI as indicated by insignificant immediate and long-lasting after-effects. Additionally, the tDCS-cog did not enhance online training as predicted. The fMRI analysis revealed brain activity alterations in right insula that may be linked to tDCS-cog intervention. In the study we discuss the insignificant behavioral results in the context of the current evidence in tDCS parameter space and opening the discussion of possible interference between trained cognitive tasks.

Mismatch negativity and clinical trajectories in psychotic disorders: Five-year stability and predictive utility

BACKGROUND

Mismatch negativity (MMN) amplitude is reduced in psychotic disorders and associated with symptoms and functioning. Due to these robust associations, it is often considered a biomarker for psychotic illness. The relationship between MMN and clinical outcomes has been examined well in early onset psychotic illness; however, its stability and predictive utility in chronic samples are not clear.

METHOD

We examined the five-year stability of MMN amplitude over two timepoints in individuals with established psychotic disorders (cases; N = 132) and never-psychotic participants (NP; N = 170), as well as longitudinal associations with clinical symptoms and functioning.

RESULTS

MMN amplitude exhibited good temporal stability (cases, r = 0.53; never-psychotic, r = 0.52). In cases, structural equation models revealed MMN amplitude to be a significant predictor of worsening auditory hallucinations (β = 0.19), everyday functioning (β = -0.13), and illness severity (β = -0.12) at follow-up. Meanwhile, initial IQ (β = -0.24), negative symptoms (β = 0.23), and illness severity (β = -0.16) were significant predictors of worsening MMN amplitude five years later.

CONCLUSIONS

These results imply that MMN measures a neural deficit that is reasonably stable up to five years. Results support disordered cognition and negative symptoms as preceding reduced MMN, which then may operate as a mechanism driving reductions in everyday functioning and the worsening of auditory hallucinations in chronic psychotic disorders. This pattern may inform models of illness course, clarifying the relationships amongst biological mechanisms of predictive processing and clinical deficits in chronic psychosis and allowing us to better understand the mechanisms driving such impairments over time.

Assessing functional ability of healthy adults with the Night Out Task

Objective: Given the negative health outcomes associated with functional loss, there is need to better understand the trajectory of functional change and compensation use with age. Many older adults successfully age in place, and there is not a one-to-one relationship between cognitive changes and ability to live independently. This study compared healthy age cohorts' performance and approach on a functional measure, particularly examining compensatory strategy use to support task performance. Methods: 57 young adults (YAs; ages 18-39), 42 young-old adults (YOAs; ages 60-69) and 47 old-old (OOAs; ages 70+) completed the Night Out Task (NOT); an open-ended functional assessment in which participants complete eight subtasks in preparation for a night out with a friend (e.g. prepare tea and gather items for a recipe). The NOT measures both primary outcome variables (e.g. time and accuracy), error types and 'compensation variables', which are process-approach variables intended to map on to the types of compensatory strategies individuals use in their everyday lives (e.g. planning and checking). Results: Results revealed that YAs performed better than the oldest group on the NOT in accuracy, execution time and number of both inefficient and inaccurate/incomplete errors. YAs additionally used fewer compensatory strategies than both older groups. Only one compensation variable had a positive relationship to outcome; double-checking was related to improved accuracy and fewer inaccurate/incomplete errors within the oldest cohort. Conclusion: Together these findings support a spectrum of functional change with age. While compensation use increased with age, the relationship between compensation use and outcome was unclear. Future work is needed to understand under what conditions older adults' self-initiate compensation use and to understand the relationship between compensation use and outcome.

Working memory impairment in children orphaned by parental HIV/AIDS: An event-related potentials study

A large body of literature has established that children orphaned by HIV/AIDS ('AIDS orphans') face numerous challenges, such as parental death, poverty, disrupted school attendance and stigma. All of these early life adversities can have long-lasting effects on brain function, especially the executive functions. Working memory, as one of the most studied aspects of executive functions, is also reported to be impaired in children with early adversity. However, limited data are available regarding how early life adverse events affect the neural dynamic associated with working memory processing in AIDS orphans. This study applied the electroencephalogram (EEG) technique to investigate the working memory process in 81 AIDS orphans and 62 non-orphan controls with n-back tasks. Results from EEG analysis and time-frequency analysis showed that AIDS orphans displayed smaller N2 and larger P2, P3 activation as well as enhanced theta and attenuated alpha band oscillations compared to the controls. The present findings indicated a deficit in working memory process in AIDS orphans and suggested that this deficit might be due to the impairments in attention allocation, detection and classification of stimuli and updating process in working memory.

Impact of working memory capacity on predominance of parietal over frontal P300 amplitude

Working memory-related neural activity varies with task load, and these neural variations can be constrained by working memory capacity (WMC). For instance, some studies suggest that parietal and frontal P300 amplitudes, reflecting working memory functioning, vary differentially with task load and WMC. The present study explored whether the predominance of parietal over frontal P300 amplitude is related to WMC, and whether this relationship varies according to task load. Thirty-one adults aged 20-40 years performed a Sternberg task with two set sizes (2 vs. 6 items), during which event-related potentials were recorded. This allowed us to explore the P300 and estimate the magnitude of its parietal over frontal predominance, calculated as a parietal over frontal predominance index (PFPI). Participants also performed the Digit Span and alpha span tests, which were used to compute an independent index of WMC. Results revealed the classic parietal over frontal P300 predominance. They also indicated that the PFPI decreased as task load increased, owing mainly to an increase in frontal P300 amplitude. Interestingly, WMC was positively correlated with the PFPI, suggesting that individuals with greater WMC exhibited greater parietal over frontal predominance. These correlations did not vary across set sizes. Parietal over frontal predominance was reduced in individuals with lower WMC, who relied more on frontal neural resources. This frontal upregulation may have reflected the recruitment of supplementary attentional executive operations to compensate for less efficient working memory maintenance operations.

Midfrontal Theta and Cognitive Control During Interlimb Coordination Across the Adult Lifespan

Interlimb coordination is required for adequate execution of most daily life activities. Yet, aging negatively affects interlimb coordination, impacting the quality of life in older people. Therefore, disentangling the underlying age-related neural mechanisms is of utmost importance. Here, we investigated neurophysiological processes of an interlimb reaction time task, including both simple and complex coordination modes. Midfrontal theta power, measured using electroencephalography (EEG), was analyzed as a marker for cognitive control. In total, 82 healthy adults participated, with 27 younger, 26 middle-aged, and 29 older adults. On a behavioral level, reaction time increased across the adult lifespan, and error rate was higher in older adults. Notably, aging disproportionately affected reaction times in the complex coordination modes, with larger reaction time increases from simple to complex movements than in younger adults, starting already at middle age. On the neurophysiological level, EEG showed that only younger adults had significantly increased levels of midfrontal theta power during complex relative to simple coordination modes, while no significant differences were found between simple and complex movements in middle-aged and older adults. The absence of this theta power upregulation with regard to movement complexity with increasing age might reflect a premature saturation of the available mental resources.

Age-related changes in midfrontal theta activity during steering control: A driving simulator study

Motor control, a ubiquitous part of driving, requires increased cognitive controlled processing in older adults relative to younger adults. However, the influence of aging on motor-related neural mechanisms in the context of driving has rarely been studied. The present study aimed to identify age-related changes in cognitive control and attention allocation during a simulated steering task, using electroencephalography. Midfrontal theta, a marker for cognitive control, and posterior alpha power, a marker for attention allocation, were measured in a total of 26 young, 25 middle-aged, and 28 older adults. By adapting driving speed, the difficulty level of this steering task was individualized for each participant. Results show age-related changes in midfrontal theta power, but not in posterior alpha power, despite similar steering accuracy across age groups. Specifically, only younger and, to a lesser extent, middle-aged adults exhibited increased theta power while driving through more demanding curved segments relative to straight segments. In contrast, theta power upregulation was absent in older adults, suggesting a saturation of cognitive resources while driving, possibly due to a limitation in resource capacity, or less automatic motor-related neural processing.

Hippocampus-centred grey matter covariance networks predict the development and reversion of mild cognitive impairment

BACKGROUND

Mild cognitive impairment (MCI) has been thought of as the transitional stage between normal ageing and Alzheimer's disease, involving substantial changes in brain grey matter structures. As most previous studies have focused on single regions (e.g. the hippocampus) and their changes during MCI development and reversion, the relationship between grey matter covariance among distributed brain regions and clinical development and reversion of MCI remains unclear.

METHODS

With samples from two independent studies (155 from the Beijing Aging Brain Rejuvenation Initiative and 286 from the Alzheimer's Disease Neuroimaging Initiative), grey matter covariance of default, frontoparietal, and hippocampal networks were identified by seed-based partial least square analyses, and random forest models were applied to predict the progression from normal cognition to MCI (N-t-M) and the reversion from MCI to normal cognition (M-t-N).

RESULTS

With varying degrees, the grey matter covariance in the three networks could predict N-t-M progression (AUC = 0.692-0.792) and M-t-N reversion (AUC = 0.701-0.809). Further analyses indicated that the hippocampus has emerged as an important region in reversion prediction within all three brain networks, and even though the hippocampus itself could predict the clinical reversion of M-t-N, the grey matter covariance showed higher prediction accuracy for early progression of N-t-M.

CONCLUSIONS

Our findings are the first to report grey matter covariance changes in MCI development and reversion and highlight the necessity of including grey matter covariance changes along with hippocampal degeneration in the early detection of MCI and Alzheimer's disease.

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.

Exergaming in older adults: the effects of game characteristics on brain activity and physical activity

Introduction

Exergames are increasingly used in rehabilitation settings for older adults to train physical and cognitive abilities. To meet the potential that exergames hold, they need to be adapted to the individual abilities of the player and their training objectives. Therefore, it is important to know whether and how game characteristics affect their playing. The aim of this study is to investigate the effect of two different kinds of exergame (step game and balance game) played at two difficulty levels on brain activity and physical activity.

Methods

Twenty-eight older independently living adults played two different exergames at two difficulty levels each. In addition, the same movements as during gaming (leaning sideways with feet in place and stepping sideways) were performed as reference movements. Brain activity was recorded using a 64-channel EEG system to assess brain activity, while physical activity was recorded using an accelerometer at the lower back and a heart rate sensor. Source-space analysis was applied to analyze the power spectral density in theta (4 Hz-7 Hz) and alpha-2 (10 Hz-12 Hz) frequency bands. Vector magnitude was applied to the acceleration data.

Results

Friedman ANOVA revealed significantly higher theta power for the exergaming conditions compared to the reference movement for both games. Alpha-2 power showed a more diverse pattern which might be attributed to task-specific conditions. Acceleration decreased significantly from the reference movement to the easy condition to the hard condition for both games.

Discussion

The results indicate that exergaming increases frontal theta activity irrespective of type of game or difficulty level, while physical activity decreases with increasing difficulty level. Heart rate was found to be an inappropriate measure in this population older adults. These findings contribute to understanding of how game characteristics affect physical and cognitive activity and consequently need to be taken into account when choosing appropriate games and game settings for exergame interventions.

Involvement of executive control in neural capacity related to working memory in aging: an ERP P300 study

Executive control could be involved in neural capacity, which corresponds to the modulation of neural activity with increased task difficulty. Thus, by exploring the P300-an electrophysiological correlate of working memory-we examined the role played by executive control in both the age-related decline in working memory and neural capacity in aging. Event-related potentials (ERPs) were recorded while younger and older participants performed a Sternberg task with two set sizes (2 vs. 6 items), allowing us to calculate a neural capacity index. Participants also completed two control tasks (Stroop and 3-back tests), which were used to calculate a composite executive control index. Results indicated that working memory performance decreased with aging and difficulty. At the neural level, results indicated that the P300 amplitude varied with aging and also with task difficulty. In the low difficulty condition, frontal P300 amplitude was higher for older than for younger adults, whereas in the high difficulty condition, the amplitude of frontal and parietal P300 did not differ between both age groups. Results also suggest that task difficulty led to a decrease in parietal amplitude in both age groups and to an increase in frontal amplitude in younger but not older adults. Both executive control and frontal neural capacity mediated the age-related variance in working memory for older adults. Moreover, executive control mediated the age-related variance in the frontal neural capacity of older adults. Thus, the present study suggests a model for older adults in which executive control deficits with advancing age lead to less efficient frontal recruitment to cope with task difficulty (neural capacity), which in turn has a negative impact on working memory functioning.

EEG-based mental fatigue detection using linear prediction cepstral coefficients and Riemann spatial covariance matrix

Objective. Establishing a mental fatigue monitoring system is of great importance as for severe fatigue may cause unimaginable consequences. Electroencephalogram (EEG) is often utilized for mental fatigue detection because of its high temporal resolution and ease of use. However, many EEG-based approaches for detecting mental fatigue only take into account the feature extraction of a single domain and do not fully exploit the information that EEG may offer.Approach. In our work, we propose a new algorithm for mental fatigue detection based on multi-domain feature extraction and fusion. EEG components representing fatigue are closely related in the past and present because fatigue is a dynamic and gradual process. Accordingly, the idea of linear prediction is used to fit the current value with a set of sample values in the past to calculate the linear prediction cepstral coefficients (LPCCs) as the time domain feature. Moreover, in order to better capture fatigue-related spatial domain information, the spatial covariance matrix of the original EEG signal is projected into the Riemannian tangent space using the Riemannian geometric method. Then multi-domain features are fused to obtain comprehensive spatio-temporal information.Main results. Experimental results prove the suggested algorithm outperforms existing state-of-the-art methods, achieving an average accuracy of 87.10% classification on the public dataset SEED-VIG (three categories) and 97.40% classification accuracy (two categories) on the dataset made by self-designed experiments.Significance. These findings show that our proposed strategy perform more effectively for mental fatigue detection based on EEG.

Repetitive Anodal TDCS to the Frontal Cortex Increases the P300 during Working Memory Processing

Transcranial direct current stimulation (TDCS) is a technique with which neuronal activity, and therefore potentially behavior, is modulated by applying weak electrical currents to the scalp. Application of TDCS to enhance working memory (WM) has shown promising but also contradictory results, and little emphasis has been placed on repeated stimulation protocols, in which effects are expected to be increased. We aimed to characterize potential behavioral and electrophysiological changes induced by TDCS during WM training and evaluate whether repetitive anodal TDCS has a greater modulatory impact on the processes underpinning WM than single-session stimulation. We examined the effects of single-session and repetitive anodal TDCS to the dorsolateral prefrontal cortex (DLPFC), targeting the frontal-parietal network, during a WM task in 20 healthy participants. TDCS had no significant impact on behavioral measures, including reaction time and accuracy. Analyzing the electrophysiological response, the P300 amplitude significantly increased following repetitive anodal TDCS, however, positively correlating with task performance. P300 changes were identified over the parietal cortex, which is known to engage with the frontal cortex during WM processing. These findings support the hypothesis that repetitive anodal TDCS modulates electrophysiological processes underlying WM.

Explainable Machine-Learning-Based Characterization of Abnormal Cortical Activities for Working Memory of Restless Legs Syndrome Patients

Restless legs syndrome (RLS) is a sensorimotor disorder accompanied by a strong urge to move the legs and an unpleasant sensation in the legs, and is known to accompany prefrontal dysfunction. Here, we aimed to clarify the neural mechanism of working memory deficits associated with RLS using machine-learning-based analysis of single-trial neural activities. A convolutional neural network classifier was developed to discriminate the cortical activities between RLS patients and normal controls. A layer-wise relevance propagation was applied to the trained classifier in order to determine the critical nodes in the input layer for the output decision, i.e., the time/location of cortical activities discriminating RLS patients and normal controls during working memory tasks. Our method provided high classification accuracy (~94%) from single-trial event-related potentials, which are known to suffer from high inter-trial/inter-subject variation and low signal-to-noise ratio, after strict separation of training/test/validation data according to leave-one-subject-out cross-validation. The determined critical areas overlapped with the cortical substrates of working memory, and the neural activities in these areas were correlated with some significant clinical scores of RLS.

Music training modulates theta brain oscillations associated with response suppression

There is growing interest in developing training programs to mitigate cognitive decline associated with normal aging. Here, we assessed the effect of 3-month music and visual art training programs on the oscillatory brain activity of older adults using a partially randomized intervention design. High-density electroencephalography (EEG) was measured during the pre- and post-training sessions while participants completed a visual GoNoGo task. Time-frequency representations were calculated in regions of interest encompassing the visual, parietal, and prefrontal cortices. Before training, NoGo trials generated greater theta power than Go trials from 300 to 500 ms post-stimulus in mid-central and frontal brain areas. Theta power indexing response suppression was significantly reduced after music training. There was no significant difference between pre- and post-test for the visual art or the control group. The effect of music training on theta power indexing response suppression was associated with reduced functional connectivity between prefrontal, visual, and auditory regions. These results suggest that theta power indexes executive control mechanisms in older adults. Music training affects theta power and functional connectivity associated with response suppression. These findings contribute to a better understanding of inhibitory control ability in older adults and the neuroplastic effects of music interventions.

Time of Day Effects on Inhibitory Functioning: Cognitive and Neural Evidence of Sundowning in Amnestic Mild Cognitive Impairment

Background: Amnestic mild cognitive impairment (aMCI), a prodromal phase of Alzheimer’s disease (AD), is characterized by episodic memory dysfunction, but inhibitory deficits have also been commonly reported. Time of day (TOD) effects have been confirmed in 1) healthy aging on cognitive processes such as inhibitory control, and 2) on behavior in AD (termed the sundowning effect), but no such research has addressed aMCI. Objective: The present study examined the impact of TOD on the behavioral and electrophysiological correlates of inhibition in 54 individuals with aMCI and 52 healthy controls (HCs), all of morning chronotype. Methods: Participants were randomly assigned to complete two inhibition tasks (Go-NoGo and Flanker) during their optimal (morning) or non-optimal (evening) TOD, while electroencephalography was recorded. Results: Both tasks elicited changes in N2 and P3 event-related potential (ERP) components, which commonly index inhibitory functioning. Analyses showed that the Go-NoGo difference in P3 amplitude was reduced in individuals with aMCI relative to HCs. Compared to HCs, the Flanker difference in P3 amplitude was also reduced and coincided with more errors in the aMCI group. Notably, these behavioral and ERP differences were exaggerated in the non-optimal TOD relative to the optimal TOD. Conclusion: Findings confirm the presence of inhibition deficits in aMCI and provide novel evidence of sundowning effects on inhibitory control in aMCI. Results reinforce the need to consider the influences of TOD in clinical assessments involving individuals with aMCI.

Neural Synchrony and Network Dynamics in Social Interaction: A Hyper-Brain Cell Assembly Hypothesis

Mounting neurophysiological evidence suggests that interpersonal interaction relies on continual communication between cell assemblies within interacting brains and continual adjustments of these neuronal dynamic states between the brains. In this Hypothesis and Theory article, a Hyper-Brain Cell Assembly Hypothesis is suggested on the basis of a conceptual review of neural synchrony and network dynamics and their roles in emerging cell assemblies within the interacting brains. The proposed hypothesis states that such cell assemblies can emerge not only within, but also between the interacting brains. More precisely, the hyper-brain cell assembly encompasses and integrates oscillatory activity within and between brains, and represents a common hyper-brain unit, which has a certain relation to social behavior and interaction. Hyper-brain modules or communities, comprising nodes across two or several brains, are considered as one of the possible representations of the hypothesized hyper-brain cell assemblies, which can also have a multidimensional or multilayer structure. It is concluded that the neuronal dynamics during interpersonal interaction is brain-wide, i.e., it is based on common neuronal activity of several brains or, more generally, of the coupled physiological systems including brains.

The Effects of Aging and Time of Day on Inhibitory Control: An Event-Related Potential Study

Time of day (TOD) influences on executive functions have been widely reported, with greater efficiency demonstrated at optimal relative to non-optimal TOD according to one's chronotype (i.e., synchrony effect). Older adults (OAs) show declines in inhibitory control and are more sensitive to the effects of circadian variation on executive functioning. To date, no studies have investigated the effects of TOD and aging on executive functioning using electrophysiological measures. The present study investigated the effects of aging and TOD on the neural correlates of inhibitory processing (N2 and P3) using event-related potentials (ERPs). Go-NoGo and Flanker tasks were administered to 52 OAs of morning chronotype and 51 younger adults (YAs) of afternoon-to-evening chronotype who were randomly assigned to morning or afternoon test sessions, with the optimal TOD for OAs in the morning and for YAs in the afternoon/evening. While behavioral results demonstrated no TOD effects, ERPs indicated synchrony effects. Both YAs and OAs showed greater modulation of Go-NoGo N2 and greater P3 amplitude during the non-optimal than optimal TOD, consistent with the synchrony effect. For the Flanker task, age differences in P3 amplitude were only apparent during the non-optimal TOD. These results suggest that processes associated with inhibitory control are differentially affected by TOD and aging, with age-related reductions in inhibitory efficiency during off-peak test times on measures of interference control. These findings highlight the sensitivity of ERPs to detect TOD effects in the absence of behavioral differences, confirm more pronounced TOD effects in OAs relative to YAs on ERP measures of interference control, and reinforce the need to assess and control for circadian typology in research studies.

Lexico-semantic access and audiovisual integration in the aging brain: Insights from mixed-effects regression analyses of event-related potentials

We investigated how aging modulates lexico-semantic processes in the visual (seeing written items), auditory (hearing spoken items) and audiovisual (seeing written items while hearing congruent spoken items) modalities. Participants were young and older adults who performed a delayed lexical decision task (LDT) presented in blocks of visual, auditory, and audiovisual stimuli. Event-related potentials (ERPs) revealed differences between young and older adults despite older adults' ability to identify words and pseudowords as accurately as young adults. The observed differences included more focalized lexico-semantic access in the N400 time window in older relative to young adults, stronger re-instantiation and/or more widespread activity of the lexicality effect at the time of responding, and stronger multimodal integration for older relative to young adults. Our results offer new insights into how functional neural differences in older adults can result in efficient access to lexico-semantic representations across the lifespan.

What Can Neural Activity Tell Us About Cognitive Resources in Aging?

A reduction in cognitive resources has been originally proposed to account for age-related decrements in several cognitive domains. According to this view, aging limits the pool of available cognitive supplies: Compared to younger adults, elderly exhaust the resources more rapidly as task difficulty increases, hence a dramatic performance drop. Neurophysiological indexes (e.g., BOLD response and EEG activity) may be instrumental to quantify the amount of such cognitive resources in the brain and to pinpoint the stage of stimulus processing where the decrement in age-related resources is evident. However, as we discuss in this mini-review, the most recent studies on the neurophysiological markers of age-related changes lack a consistent coupling between neural and behavioral effects, which casts doubt on the advantage of measuring neural indexes to study resource deployment in aging. For instance, in the working memory (WM) domain, recent cross-sectional studies found varying patterns of concurrent age-related brain activity, ranging from equivalent to reduced and increased activations of old with respect to younger adults. In an attempt to reconcile these seemingly inconsistent findings of brain-behavior coupling, we focus on the contribution of confounding sources of variability and propose ways to control for them. Finally, we suggest an alternative perspective to explain age-related effects that implies a qualitative (instead of or along with a quantitative) difference in the deployment of cognitive resources in aging.

Response inhibition and memory updating in the count/nocount task: an ERP study

The present study aimed to separate the neural activities between response inhibition and memory updating processes in the Count/Nocount task. Memory load was manipulated to investigate the memory updating process. Within each trial, participants were asked to count/withhold counting the number of O/X letters in the Count/Nocount task. The participants were asked to silently add 1 if a Count letter was presented in the low load condition, and add 2 in the high load condition. Data from 28 healthy participants showed that: (1) in both high load and low load conditions, the latencies of P2 and N2 components were shorter for the Nocount than Count trials, indicating faster attentional orienting and conflict monitoring processes for the Nocount stimuli (i.e., inhibition processes triggered by the Nocount stimuli against those response execution processes triggered by Count stimuli); (2) more positive frontal P3 amplitudes were evoked for the Nocount relative to the Count stimuli, indicating a more intensive response inhibition process for the Nocount trials; (3) a more positive parietal P3 component was evoked for the low load relative to high load condition, indicating a more intensive working memory updating process for the high load condition. This load effect was absent for the frontal P3 component, suggesting that the frontal P3 might not be associated with the memory updating process. In sum, both the cognitive inhibition process (reflected by the frontal P3 component) and working memory updating process (reflected by the parietal P3 component) appear to be involved in the Count/Nocount task.

Examining the role of ovarian hormones in the association between worry and working memory across the menstrual cycle

Previous research indicates that worry is associated with poorer working memory performance. Moreover, prior work demonstrates that estradiol relates to both worry and working memory performance. In the present study, we sought to further examine interrelations between worry, estradiol and working memory by testing whether estradiol moderates the association between worry and working memory in females. We hypothesized that worry would be associated with poorer working memory performance at higher levels of estradiol. We also conducted exploratory analyses to examine the role of progesterone as a moderator of the association between worry and working memory. Participants were 97 naturally-cycling females who attended four lab sessions across their menstrual cycles. Consistent with predictions, higher average levels of worry were associated with lower working memory accuracy on particularly difficult trials when average levels of estradiol were also high. The same association between higher worry and lower working memory accuracy emerged when average levels of progesterone were high. Findings highlight the importance of considering ovarian hormones in future studies and current theories of anxiety and cognition.

Altered event-related potentials and theta oscillations index auditory working memory deficits in healthy aging

Speech comprehension deficits constitute a major issue for an increasingly aged population, as they may lead older individuals to social isolation. Since conversation requires constant monitoring, updating and selecting information, auditory working memory decline, rather than impoverished hearing acuity, has been suggested a core factor. However, in stark contrast to the visual domain, the neurophysiological mechanisms underlying auditory working memory deficits in healthy aging remain poorly understood, especially those related to on-the-fly information processing under increasing load. Therefore, we investigated the behavioral costs and electrophysiological differences associated with healthy aging and working memory load during continuous auditory processing. We recorded EEG activity from 27 younger (∼25 years) and 29 older (∼70 years) participants during their performance on an auditory version of the n-back task with speech syllables and 2 workload levels (1-back; 2-back). Behavioral measures were analyzed as indices of function; event-related potentials as proxies for sensory and cognitive processes; and theta oscillatory power as a reflection of memory and central executive function. Our results show age-related differences in auditory information processing within a latency range that is consistent with a series of impaired functions, from sensory gating to cognitive resource allocation during constant information updating, especially under high load.

Anterior Cingulate Cortex Activity During Rest Is Related to Alterations in Pain Perception in Aging

Alterations in the affective component of pain perception are related to the development of chronic pain and may contribute to the increased vulnerability to pain observed in aging. The present study analyzed age-related changes in resting-state brain activity and their possible relation to an increased pain perception in older adults. For this purpose, we compared EEG current source density and fMRI functional-connectivity at rest in older (n = 20, 66.21 ± 3.08 years) and younger adults (n = 21, 20.71 ± 2.30 years) and correlated those brain activity parameters with pain intensity and unpleasantness ratings elicited by painful stimulation. We found an age-related increase in beta2 and beta3 activity in temporal, frontal, and limbic areas, and a decrease in alpha activity in frontal areas. Moreover, older participants displayed increased functional connectivity in the anterior cingulate cortex (ACC) and the insula with precentral and postcentral gyrus. Finally, ACC beta3 activity was positively correlated with pain intensity and unpleasantness ratings in older, and ACC-precentral/postcentral gyrus connectivity was positively correlated with unpleasantness ratings in older and younger participants. These results reveal that ACC resting-state hyperactivity is a stable trait of brain aging and may underlie their characteristic altered pain perception.

Short-Term Audiovisual Spatial Training Enhances Electrophysiological Correlates of Auditory Selective Spatial Attention

Audiovisual cross-modal training has been proposed as a tool to improve human spatial hearing. Here, we investigated training-induced modulations of event-related potential (ERP) components that have been associated with processes of auditory selective spatial attention when a speaker of interest has to be localized in a multiple speaker ("cocktail-party") scenario. Forty-five healthy participants were tested, including younger (19-29 years; n = 21) and older (66-76 years; n = 24) age groups. Three conditions of short-term training (duration 15 min) were compared, requiring localization of non-speech targets under "cocktail-party" conditions with either (1) synchronous presentation of co-localized auditory-target and visual stimuli (audiovisual-congruency training) or (2) immediate visual feedback on correct or incorrect localization responses (visual-feedback training), or (3) presentation of spatially incongruent auditory-target and visual stimuli presented at random positions with synchronous onset (control condition). Prior to and after training, participants were tested in an auditory spatial attention task (15 min), requiring localization of a predefined spoken word out of three distractor words, which were presented with synchronous stimulus onset from different positions. Peaks of ERP components were analyzed with a specific focus on the N2, which is known to be a correlate of auditory selective spatial attention. N2 amplitudes were significantly larger after audiovisual-congruency training compared with the remaining training conditions for younger, but not older, participants. Also, at the time of the N2, distributed source analysis revealed an enhancement of neural activity induced by audiovisual-congruency training in dorsolateral prefrontal cortex (Brodmann area 9) for the younger group. These findings suggest that cross-modal processes induced by audiovisual-congruency training under "cocktail-party" conditions at a short time scale resulted in an enhancement of correlates of auditory selective spatial attention.

Neuroanatomy of complex social emotion dysregulation in adolescent offenders

Social emotions require the correct integration of emotional, cognitive, and social processes and are critical for complex social interactions. Adolescent criminal offenders (AOs) show abnormalities in the experience of basic emotions. However, most research has focused solely on basic emotions, neglecting complex social emotions that could be critical for social reintegration. The purpose of this study was to investigate the behavioral and neural correlates of social emotions (envy and Schadenfreude) in AOs. We explored the experience of complex social emotions, as well as their anatomical correlates, in AOs (n = 19) and a nonoffenders control group (NOs, n = 20). Additionally, we assessed the relationship between social emotions, executive functions (EFs), and fluid intelligence (FI). Structural brain imaging was obtained in all participants. The results showed that AOs had significantly lower envy and Schadenfreude ratings and exhibited lower performance in EFs compared with NOs. The measurement of EFs relied on the INECO frontal screening (IFS). Experiencing fewer social emotions was associated with diminished EFs but not with FI. Moreover, in AOs, reduced levels of envy and Schadenfreude were linked with reduced gray matter volumes in regions subserving mentalizing abilities (inferior parietal lobe and precuneus) and socioemotional processing (inferior and middle temporal regions), as well as key hubs of the executive frontoparietal network (inferior parietal lobule, orbital and rectus gyri). Additional analysis on the AOs revealed no associations between the type of crime and our variables of interest (EFs, FI and social emotions). Our findings are the first to provide evidence on abnormalities in the experience of social emotions in AOs that are associated with neurocognitive markers of social cognition and EFs. Understanding social emotions and their abnormalities (under-experience) as complex intertwined processes may have important future translational implications, including risk prediction for social adaptation/reintegration, sociocognitive targeted interventions, and skill training for social emotions in vulnerable populations.

The discrepant effect of acute stress on cognitive inhibition and response inhibition

This study aimed to investigate how acute stress impinges on individual's cognitive inhibition and response inhibition abilities. Electroencephalography was adopted when 35 healthy adult females performing the No Go Flanker task before and after the Trier Social Stress Test. Both inhibition processes evoked N2 and P3 components, but only the response inhibition evoked the late positive potential (LPP), indicating the response inhibition needed continuous cognitive effort to inhibit the prepotent response. The N2 and the P3 amplitudes were decreased, while the LPP amplitudes were increased under acute stress. These results suggested that acute stress caused the detrimental effect by occupying cognitive resources. Contrastingly, individuals actively regulated and made more efforts to counteract the detrimental effect of acute stress on response inhibition. Thus, acute stress impaired cognitive inhibition but did not affect response inhibition.

Effects of multi-domain cognitive training on working memory retrieval in older adults: behavioral and ERP evidence from a Chinese community study

Working memory (WM) is a fundamental cognitive function that typically declines with age. Previous studies have shown that targeted WM training has the potential to improve WM performance in older adults. In the present study, we investigated whether a multi-domain cognitive training program that was not designed to specifically target WM could improve the behavioral performance and affect the neural activity during WM retrieval in healthy older adults. We assigned healthy older participants (70-78 years old) from a local community into a training group who completed a 3-month multi-domain cognitive training and a control group who only attended health education lectures during the same period. Behavioral and electroencephalography (EEG) data were recorded from participants while performing an untrained delayed match or non-match to category task and a control task at a pre-training baseline session and a post-training follow-up session. Behaviorally, we found that participants in the training group showed a trend toward greater WM performance gains than participants in the control group. Event-related potential (ERP) results suggest that the task-related modulation of P3 during WM retrieval was significantly enhanced at the follow-up session compared with the baseline session, and importantly, this enhancement of P3 modulation was only significant in the training group. Furthermore, no training-related effects were observed for the P2 or N2 component during WM retrieval. These results suggest that the multi-domain cognitive training program that was not designed to specifically target WM is a promising approach to improve WM performance in older adults, and that training-related gains in performance are likely mediated by an enhanced modulation of P3 which might reflect the process of WM updating.

Load-dependent modulation of alpha oscillations during working memory encoding and retention in young and older adults

Working memory (WM) is vulnerable to age-related decline, particularly under high loads. Visual alpha oscillations contribute to WM performance in younger adults, and although alpha decreases in power and frequency with age, it is unclear if alpha activity supports WM in older adults. We recorded electroencephalography (EEG) while 24 younger (aged 18-35 years) and 30 older (aged 50-86) adults performed a modified Sternberg task with varying load conditions. Older adults demonstrated slower reaction times at all loads, but there were no significant age differences in WM capacity. Regardless of age, alpha power decreased and alpha frequency increased with load during encoding, and the magnitude of alpha suppression during retention was larger at higher loads. While alpha power during retention was lower than fixation in older, but not younger adults, the relative change from fixation was not significantly different between age groups. Individual differences in alpha power did not predict performance for either age groups or at any WM loads. We demonstrate that alpha power and frequency are modulated in a similar task- and load-dependent manner during WM in both older and younger adults when WM performance is comparable across age groups. IMPACT STATEMENT: Aging is associated with a marked decrease in the power and frequency of alpha oscillations. Here, we demonstrate that when verbal working memory performance is matched across age groups, alpha power and frequency are modulated in a similar task- and load-dependent manner in both young and older adults.

Electrophysiological correlates of the Categorization Working Memory Span task in older adults

Older adults typically show poor performance in tasks assessing working memory (WM), a crucial cognitive mechanism. The present study examined the electrophysiological correlates of a classic complex WM task often used in studies involving older adults, the Categorization Working Memory Span task (CWMS), by means of event-related potentials. Thirty-five healthy, right-handed older adults (64-75 years) were presented the CWMS task while a 38-channel EEG was measured, and the N1, P1, and word recognition potential (RP) were analyzed on four regions of interest (ROIs) of 5 electrodes each. Additionally, late positive components (P200 and P300) were analyzed in midline ROIs of 3 electrodes each. Participants also executed an n-back task (2-back condition) and an objective performance-based task (the Ability to solve Problems in Everyday life [APE]). At a behavioral level, significant correlations were found between the CWMS, the 2-back, and the APE tests. At a physiological level, N1 and word RP showed greater bilateral amplitude in posterior electrodes, but the better the CWMS and the 2-back performance, the greater the RP amplitude on posterior left sites. The CWMS task induced a clear P200 component, but its amplitude was not correlated with participants' behavioral performance. Altogether, notwithstanding that the bilateral RP pattern elicited by the CWMS is a clear marker of WM processing in older adults, better elderly performers on this complex WM test showed greater left hemisphere dominance to the automatic word RP.

An exploratory Study of EEG Alpha Oscillation and Pupil Dilation in Hearing-Aid Users During Effortful listening to Continuous Speech

Individuals with hearing loss allocate cognitive resources to comprehend noisy speech in everyday life scenarios. Such a scenario could be when they are exposed to ongoing speech and need to sustain their attention for a rather long period of time, which requires listening effort. Two well-established physiological methods that have been found to be sensitive to identify changes in listening effort are pupillometry and electroencephalography (EEG). However, these measurements have been used mainly for momentary, evoked or episodic effort. The aim of this study was to investigate how sustained effort manifests in pupillometry and EEG, using continuous speech with varying signal-to-noise ratio (SNR). Eight hearing-aid users participated in this exploratory study and performed a continuous speech-in-noise task. The speech material consisted of 30-second continuous streams that were presented from loudspeakers to the right and left side of the listener (±30° azimuth) in the presence of 4-talker background noise (+180° azimuth). The participants were instructed to attend either to the right or left speaker and ignore the other in a randomized order with two different SNR conditions: 0 dB and -5 dB (the difference between the target and the competing talker). The effects of SNR on listening effort were explored objectively using pupillometry and EEG. The results showed larger mean pupil dilation and decreased EEG alpha power in the parietal lobe during the more effortful condition. This study demonstrates that both measures are sensitive to changes in SNR during continuous speech.

Probing the relationship between late endogenous ERP components with fluid intelligence in healthy older adults

The world population is rapidly aging, bringing together the necessity to better understand the advancing age. This characterization may be used to aid early diagnosis and to guide individually-tailored interventions. While some event-related potential (ERP) components, such as the P300 and late positive complex (LPC), have been associated with fluid intelligence (Gf) in young population; little is known whether these associations hold for older people. Therefore, the main goal of this study was to assess whether these ERP components are associated with Gf in the elderly. Fifty-seven older adults performed a continuous performance task (CPT) and a visual oddball paradigm while EEG was recorded. Participants were divided into two groups, according to their performance in the Raven’s Advanced Progressive Matrices test: high-performance (HP) and low-performance (LP). Results showed that the HP group, compared to the LP group, had higher LPC amplitudes in the CPT and shorter P300 latencies in the oddball task, highlighting the role of ERP components as a potential electrophysiological proxy of Gf abilities in the elderly.

Cognitive functions of shift workers: paramedics and firefighters - an electroencephalography study

Introduction. Working shifts has a negative impact on employee health and cognitive efficiency. The purpose of this study was to investigate the impact of shift work on cognitive functions - attention and working memory - using both behavioural and electrophysiological measures. Methods. The study was carried out on a group of 34 shift employees (18 paramedics, 16 firefighters) and on 17 day workers. Participants performed the attention network test and the N-back task with two conditions (1-back, 2-back) while the electroencephalography signal was recorded. Results. Observations included a higher amplitude of the P200 potential in paramedics (compared to the control group), a higher amplitude of the P300 potential after work than on a day off and the lowest increase in power in the θ band after the night shift. In firefighters, lower α desynchronization and lower synchronization in the α/β band were observed after a 24-h shift. Paramedics and firefighters had longer reaction times (N-back task). Conclusions. The results suggest that paramedics experience problems with sustained attention. Paramedics process visual stimuli in a different way; after a night shift, performing the tasks required more engagement of cognitive resources. For firefighters, a decrease in visual attention functions and cognitive inhibition was observed.