Eyes-closed Condition Research Articles

Evaluating the impact of soft bracing and textile engineering in enhancing postural control and proprioception in adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) is often associated with unbalanced posture and proprioceptive deficits and is particularly prone to progression during puberty. However, limited research has addressed early intervention for mild curves (10-20 degrees). This study aims to examine the effects of a soft bracing intervention using the Posture Correction Girdle (PCG) on 3D postural balance and proprioception in adolescents with early-stage scoliosis. Cobb angles were measured with the X-ray Imaging before and after a 2-h wear trial with the girdle to assess immediate curve reduction. Postural angles were visualized using 3D body scanning. Proprioception was assessed using a motion capture system, focusing on trunk, neck, elbow, and knee movements under the eye-open and eye-closed condition. Data were analyzed using descriptive statistics, t-tests, and Pearson’s correlation and partial Mantel tests to examine postural balance and proprioceptive outcomes. Results indicated significant improvements in postural balance in the frontal and sagittal planes, and proprioception in the dominant-side elbow. However, other proprioceptive measures showed limited changes, with responses differing by spinal curvature. Strong correlations emerged between proprioceptive function and postural angles in the thoracic and lumbar regions. These findings suggest that soft bracing can enhance postural control for mild AIS, though individual variability in responses highlights the need for personalized bracing strategies. This study supports soft bracing as a promising therapeutic option, underscoring the importance of individualized assessment to optimize brace design and effectiveness in early-onset scoliosis management.

The effects of sleep deprivation on the balance system: following normal sleep, 24h of sleep deprivation, and rest under eyes-open and eyes-closed conditions.

This study investigated the effects of sleep deprivation (SD) on balance after normal sleep, 24h of SD, and subsequent rest under eyes-open (EO) and eyes-closed (EC) conditions. Our aim was to ascertain whether the reduced efficiency of balance control following SD is generalized or selective. Nineteen participants (12 females, 7 males) completed the Pittsburgh Sleep Quality Index (PSQI). The mean ages for male participants were 24.14 ± 0.37years, their height was 180.71 ± 5.46cm, and weight of male participants were 81.71 ± 13.42kg. For female participants, the mean ages were 24.41 ± 4.01years, their height was 163.66 ± 2.64cm, and their weight was 59.54 ± 9.18kg. Stance analyses were conducted after normal sleep, 24h of SD, and subsequent rest of both the EO and EC. Participants performed a normal balance test, a second test while holding cubes and counting backwards from 200 by sevens, and a third test after rest under EO and EC. Independent samples t-tests showed significant height and weight differences between sexes (p < 0.05), with females generally smaller. No significant differences were found in age, daytime sleep duration, or PSQI score (p > 0.05). Significant differences in parameters such as length of the minor axis (lomna), angle, and area were observed in EO and EC across the three days, revealing the interplay between visual stimuli, cognitive tasks, and parameter stability. SD has multifaceted impacts on motor and cognitive performance, even when attentional and sensory resources are not strained. Our findings elucidate the nuanced impact of SD on cognitive performance, and suggest the efficacy of external factors in mitigating its effects on postural control.

Single-Leg Balance and Lower Limb Strength: Quantitative Analysis with the Balance Master System.

Objective: This study investigates the relationship between lower limb strength and postural stability in single-leg stance using the Balance Master system. Methods: The research involved 64 participants divided into sedentary and physically active groups based on metabolic equivalents of task (METs) values, normal weight, overweight, and obese according to body composition. Postural control was evaluated using the Sensory Organization Test. Results: The results showed that there were no significant differences in mean and maximum lower limb strength between the groups. Furthermore, postural stability in open and closed eyes conditions did not show significant differences between the groups. However, a significant positive correlation was observed between lower limb strength and stability in single-leg stance with eyes open. Conclusions: These findings suggest that lower limb muscle strength is essential for postural stability, especially when vision is available to aid balance. The study highlights the importance of interventions focused on strengthening muscles to improve physical functionality in adults.

Effect of Hard- and Soft-Density Insoles on the Postural Control of Adults over 65 Years of Age: A Cross over Clinical Trial.

there is a high risk of falls in older adults. One of the factors contributing to fall episodes is advancing age due to deterioration of the proprioceptive system. Certain clinical procedures improve balance and posture, such as the use of insoles. the objective of this study was to evaluate the impact of hard and soft insoles on static foot balance in healthy older adults compared to barefoot people. a clinical trial was conducted with a sample size of 150 healthy adults (69 male and 81 women) with a mean age of 69.03 ± 3.82 years. Postural control was evaluated in different conditions of barefoot balance with hard and soft insoles. All tests were statistically significant (p < 0.001). The test with soft insoles presented higher stabilometric values and presented worse postural control compared to the barefoot and hard insoles in all eyes-open and eyes-closed conditions. Hard and soft insoles show no improvement in postural control compared to barefoot standing. The findings suggest that soft insoles may result in impaired balance during standing. The density of the materials in the insoles emerges as a significant factor influencing postural control.

The Effects of Ankle and Foot Exercises on Ankle Strength, Balance, and Falls in Older People: A Systematic Review and Meta-Analysis.

Ankle-foot control is essential to maintain balance and gait stability. However, there has been limited evidence on the effect of ankle-foot exercises on balance and falls in older people. This study aimed to summarize the effects of ankle-foot exercises on ankle flexibility and strength, balance, mobility, and falls in older people, and to identify determining factors for ankle-foot exercises to improve balance and mobility. CINAHL, Embase, PubMed, and PEDro were searched to identify randomized controlled trials that studied the effects of ankle-foot exercises on ankle control, balance, and falls in older people. PEDro scale was used to evaluate the methodological quality of the studies. Meta-analyses were done for similar outcomes. The quality of evidence was rated by GRADE. Sixteen papers (n = 651) were included. Meta-analyses showed that ankle-foot exercises significantly improved ankle plantarflexion strength (SMD = 0.35, 95% CI = 0.04 to 0.65, low-quality evidence), ankle flexibility (SMD = 0.48, 95% CI = -0.01 to 0.96, low-quality evidence), and balance in an eyes-open condition (SMD = 0.41, 95% CI = 0.19 to 0.70, low-quality evidence). There was no significant change in ankle dorsiflexion strength (SMD = 0.29, 95% CI = -0.24 to 0.82, very low-quality evidence), balance under eyes-closed condition (SMD = 0.41, 95% CI = -0.1 to 0.92, very low-quality evidence), and gait speed (SMD = 0.36, 95% CI = -0.24 to 0.96, very low-quality evidence). Two studies reported insignificant findings on fear of falling, fall incidence, and risk of falls. Very low to low-quality evidence showed that ankle-foot exercises effectively improve ankle plantarflexion strength, flexibility, and balance with eyes open, whereas no effect on falls was found. Improvements in balance and gait tend to be associated with improvements in ankle strength and flexibility. Toe-strengthening exercise and training 3 times per week appear to be important for improving balance. This review suggested that ankle-foot exercises might improve balance in older people. Determining factors leading to improvement in balance and mobility were identified. It paves the ground for further research to study the effect of ankle-foot exercises on fall prevention.

Modulation of neural networks and symptom correlated in fibromyalgia: A randomized double-blind multi-group explanatory clinical trial of home-based transcranial direct current stimulation.

Transcranial direct current stimulation (tDCS) might modulate neural activity and promote neural plasticity in patients with fibromyalgia (FM). This multi-group randomized clinical trial compared home-based active tDCS (HB-a-tDCS) on the left dorsolateral prefrontal cortex (l-DLPFC) or home-based sham tDCS (HB-s-tDCS), and HB-a-tDCS or HB-s-tDCS on the primary motor cortex (M1) in the connectivity analyses in eight regions of interest (ROIs) across eight resting-state electroencephalography (EEG) frequencies. We included 48 women with FM, aged 30 to 65, randomly assigned to 2:1:2:1 to receive 20 sessions during 20 minutes of HB-a-tDCS 2mA or HB-s-tDCS, over l-DLPFC or M1, respectively. EEG recordings were obtained before and after treatment with eyes open (EO) and eyes closed (EC). In the EC condition, comparing pre to post-treatment, the HB-a-tDCS on l-DLPFC decreased the lagged coherence connectivity in the delta frequency band between the right insula and left anterior cingulate cortex (ACC) (t = -3.542, p = .048). The l-DLPFC HB-a-tDCS compared to HB-s-tDCS decreased the lagged coherence connectivity in the delta frequency band between the right insula and left ACC (t = -4.000, p = .017). In the EO condition, the l-DLPFC HB-a-tDCS compared to M1 HB-s-tDCS increased the lagged coherence connectivity between the l-DLPFC and left ACC in the theta band (t = -4.059, p = .048). Regression analysis demonstrated that the HB-a-tDCS effect on the l-DLPFC was positively correlated with sleep quality. On the other hand, the HB-a-tDCS on l-DLPFC and HB-s-tDCS on M1 were positively correlated with pain catastrophizing. These results show that HB-a-tDCS affects the neural connectivity between parts of the brain that control pain's emotional and attentional aspects, which are most noticeable at lower EEG frequencies in a rest state. This effect on neural oscillations could serve as a neural marker associated with its efficacy in alleviating fibromyalgia symptoms. identifier [NCT03843203].

Quantitative EEG and its relationship with attentional control in patients with anxiety disorders.

Attentional control is crucial in the development and maintenance of anxiety disorders. Understanding the underlying mechanisms of attentional control can help to shed light on the neuropathological processes in anxiety disorders (ANX). Quantitative electroencephalography (QEEG) offers a cost-effective, noninvasive method for examining the neuropathological mechanisms of mental disorders. In this study, 67 patients with ANX and 45 healthy controls (HC) were recruited. EEG recordings were obtained for 5 minutes in an eyes-closed condition. QEEG was employed to evaluate the mechanisms of attentional control in ANX. Neurophysiological measures indicated that anxiety patients exhibited a more frontal topographic pattern of theta/beta ratio (TBR) compared to HC. Additionally, a significant decrease in temporal beta power was observed in the ANX group. Correlation analysis revealed that decreased beta power and increased TBR were significant association between attentional control deficits in ANX. These findings provide electrophysiological evidence of impaired attentional control processing in anxiety patients, characterized by decreased temporal beta power and increased frontal TBR. Temporal beta power and frontal TBR may serve as promising biomarkers for attentional control in ANX.

Unveiling Frequency-Specific Microstate Correlates of Anxiety and Depression Symptoms.

Electroencephalography (EEG) microstates are canonical voltage topographies that reflect the temporal dynamics of brain networks on a millisecond time scale. Abnormalities in broadband microstate parameters have been observed in subjects with psychiatric symptoms, indicating their potential as clinical biomarkers. Considering distinct information provided by specific frequency bands of EEG, we hypothesized that microstates in decomposed frequency bands could provide a more detailed depiction of the underlying neuropathological mechanism. In this study, with a large open access resting-state dataset (n = 203), we examined the properties of frequency-specific microstates and their relationship with anxiety and depression symptoms. We conducted clustering on EEG topographies in decomposed frequency bands (delta, theta, alpha and beta), and determined the number of clusters with a meta-criterion. Microstate parameters, including global explained variance (GEV), duration, coverage, occurrence and transition probability, were calculated for eyes-open and eyes-closed states, respectively. Their ability to predict the severity of depression and anxiety symptoms were systematically identified by correlation, regression and classification analyses. Distinct microstate patterns were observed across different frequency bands. Microstate parameters in the alpha band held the best predictive power for emotional symptoms. Microstates B (GEV, coverage) and parieto-central maximum microstate E (coverage, occurrence, transitions from B to E) in the alpha band exhibited significant correlations with depression and anxiety, respectively. Microstate parameters of the alpha band achieved predictive R-square of 0.100 for anxiety scores, which is much higher than those of broadband (R-square = -0.026, p < 0.01). Similar results were found in classification of participants with high and low anxiety symptom scores (68% accuracy in alpha vs. 52% in broadband). These results suggested the value of frequency-specific microstates in predicting emotional symptoms.

Shared oscillatory mechanisms of alpha-band activity in prefrontal regions in eyes open and closed state using a portable EEG acquisition device

Alpha oscillations are associated with various psychiatric disorders, with many studies focusing on the prefrontal cortex, where transcranial alternating current stimulation (TACS) is applied in the alpha frequency band. This approach often involves selecting individualized alpha frequencies to resonate with their endogenous alpha oscillations. While strong alpha oscillations (8–13 Hz) are typically induced when the eyes are closed, they can also occur during the resting state with eyes open. However, it remains unclear whether these alpha oscillations share a common neural generation mechanism. Exploring which of these alpha oscillations is more suitable as a stable alpha peak frequency is a question of significant interest. Therefore, to systematically study this issue, we specifically collected resting-state electroencephalographic (EEG) data from the prefrontal region of 40 individuals, under both eyes-open and closed- eye conditions, with multiple follow-ups extending up to nine months. Through spectral analysis on each person’s entire dataset and averaging the results, we observed a significant positive correlation between the alpha-band power in the eyes-open and the eyes-closed states, in terms of both absolute power and relative power. Further analysis revealed that this correlation was primarily contributed by the periodic activity within the alpha band. Upon modelling the oscillatory components, we discovered distinct differences in the oscillatory characteristics-such as number of the alpha sub-oscillations between the eyes-open state and the eyes-closed state. Our study is the first to systematically explored the relationship between alpha oscillations in the prefrontal cortex in the eyes-open and eyes-closed states, identifying both shared part of the neural generation mechanism and some distinct neural mechanisms that are unique to each state.

Brainwave Patterns and Metabolic Adaptations in Rowers Crossing the Atlantic: A Case Series Pilot Study.

This pilot study was designed to test the hypothesis that quantitative electroencephalographic (qEEG) measurements reflect physiological adaptations for brain energy reallocation. The study focused on a team of three well-matched male rowers participating in a 30-day, 2,650-mile continuous transatlantic rowing competition, examining the effects of extreme, prolonged stress on brain function and metabolic adaptations. Measurements at the start and finish lines included body weight, height, waist circumference, body fat, and a panel of hormones and biochemical markers. Post-race qEEG parameters were recorded under eyes-open (EO) and eyes-closed (EC) conditions. qEEG data were compared to a reference population (ages 6-90 years) and to an age-matched 27-year-old male medical student serving as a control subject. qEEG analysis evaluated voltage amplitudes, wave distribution patterns, theta-to-beta ratios (TBR), and coherence levels. Hormonal changes and oxidative stress markers were also assessed before and after race. Two rowers exhibited post-race dominance of high-frequency beta activity, while one displayed co-dominance of delta and beta waves. Compared to the control subject (TBR = 1.25), the rowers' low TBRs (< 0.2) indicated high vigilance and low relaxation during EC conditions. Cortisol levels increased in all rowers and were associated with beta coherence >1 SD above the reference mean. Testosterone decreased in two rowers but increased in one; the smallest cortisol increase corresponded with the largest testosterone decrement. Decreases in oxidative stress markers correlated with a shift from right- to left-sided alpha asymmetry, consistent with redistribution of alpha wave energy to the nondominant hemisphere. This pattern was also observed in the control subject. Increased testosterone in one rower was linked to a decrease in the percentage of sites exhibiting normal theta frequencies, indicating a potential role for testosterone in brain energy reallocation. The findings suggest that qEEG measurements reflect physiological adaptations in response to extreme stress, supporting the hypothesis that metabolic energy is reallocated to optimize vigilance and performance. The observed correlations between hormonal changes, oxidative stress markers, and qEEG parameters provide preliminary evidence of mechanisms for brain energy reallocation. These insights highlight the potential for qEEG to identify biomarkers of stress adaptation and lay the groundwork for larger studies to further elucidate these mechanisms.

Learning Interpretable Brain Functional Connectivity via Self-Supervised Triplet Network With Depth-Wise Attention.

Brain functional connectivity has been widely explored to reveal the functional interaction dynamics between the brain regions. However, conventional connectivity measures rely on deterministic models demanding application-specific empirical analysis, while deep learning approaches focus on finding discriminative features for state classification, having limited capability to capture the interpretable connectivity characteristics. To address the challenges, this study proposes a self-supervised triplet network with depth-wise attention (TripletNet-DA) to generate the functional connectivity: 1) TripletNet-DA firstly utilizes channel-wise transformations for temporal data augmentation, where the correlated & uncorrelated sample pairs are constructed for self-supervised training, 2) Channel encoder is designed with a convolution network to extract the deep features, while similarity estimator is employed to generate the similarity pairs and the functional connectivity representations, 3) TripletNet-DA applies Triplet loss with anchor-negative similarity penalty for model training, where the similarities of uncorrelated sample pairs are minimized to enhance model's learning capability. Experimental results on pathological EEG datasets (Autism Spectrum Disorder, Major Depressive Disorder) indicate that 1) TripletNet-DA demonstrates superiority in both ASD discrimination and MDD classification than the state-of-the-art counterparts, where the connectivity features in beta & gamma bands have respectively achieved the accuracy of 97.05%, 98.32% for ASD discrimination, 89.88%, 91.80% for MDD classification in the eyes-closed condition and 90.90%, 92.26% in the eyes-open condition, 2) TripletNet-DA enables to uncover significant differences of functional connectivity between ASD EEG and TD ones, and the prominent connectivity links are in accordance with the empirical findings, thus providing potential biomarkers for clinical ASD analysis.

Resting-State Electroencephalogram Complexity Is Associated With Oral Ketamine Treatment Response: A Bayesian Analysis of Lempel-Ziv Complexity and Multiscale Entropy.

Subanesthetic doses of ketamine are a promising novel treatment for suicidality; however, the evidence for predictive biomarkers is sparse. Recently, measures of complexity, including Lempel-Ziv complexity (LZC) and multiscale entropy (MSE), have been implicated in ketamine's therapeutic action. We evaluated electroencephalogram (EEG)-derived LZC and MSE differences between responders and nonresponders to oral ketamine treatment. A total of 31 participants received six single, weekly (titrated) doses of oral racemic ketamine (0.5-3mg/kg) and underwent EEG scans at baseline (Week 0), post-treatment (Week 6), and follow-up (Week 10). Resting-state (eyes closed and open) recordings were processed in EEGLAB, and complexity metrics were extracted using the Neurokit2 package. Participants were designated responders or nonresponders by clinical response (Beck Suicide Scale [BSS] score reduction of ≥50% from baseline to the respective timepoint or score ≤6) and then compared in terms of complexity across resting-state conditions and time. Employing a Bayesian mixed effects model, we found strong evidence that LZC was higher in the eyes-open compared to eyes-closed condition, as were MSE scales 1-3. At a global level, responders displayed elevated eyes-open baseline complexity compared to nonresponders, with these values decreasing from baseline to post-treatment (Week 6) in responders only. Exploratory analyses revealed that the elevated baseline eyes-open LZC in responders was spatially localized to the left frontal lobe (F1, AF3, FC1, and F3). EEG-complexity metrics may be sensitive biomarkers for evaluating and predicting oral ketamine treatment response, with the left prefrontal cortex bein a possible treatment response region.

Posterior Correction and Fusion Using a 4D Anatomical Spinal Reconstruction Technique Improves Postural Stability Under the Eye-Closed Condition in Patients with Adolescent Idiopathic Scoliosis.

Background: Patients with adolescent idiopathic scoliosis (AIS) has been reported to exhibit impaired postural stability. Posterior correction and fusion using four-dimensional (4D) anatomical spinal reconstruction techniques may improve postural stability to correct the spine for optimal anatomical alignment. This prospective study aimed to determine the effect of posterior correction and fusion using a 4D anatomical spinal reconstruction technique on postural stability in the eye-open and eye-closed standing position in patients with thoracic AIS. Methods: Thirty-three patients with AIS, excluding those with Lenke type 5C AIS, participated in the study. The mean and standard deviation of the minimum values of the time-to-boundary (TTB) were determined. All patients were asked to perform the quiet standing position under the eye-open and eye-closed condition on a force plate preoperatively and at 1 week and 2 years postoperatively. The TTB value was calculated from the velocity and distance to the foot boundary of the acquired center-of-pressure data. Results: Under the eye-closed condition, the mean and standard deviation of the minimum TTB were significantly higher at 2 years postoperatively than preoperatively and at 1 week postoperatively. The mean and standard deviation of the minimum TTB values were significantly lower at 1 week postoperatively than preoperatively. Conclusions: The results of this study suggest that surgery using the 4D anatomical spinal reconstruction technique reduces postural stability immediately after surgery; however, it improves postural stability at 2 years compared to the preoperative values.

Effects of Neuromuscular Training on Postural Balance and Physical Performance in Older Women: Randomized Controlled Trial.

Background: Aging causes morphological and physiological changes, especially in the musculoskeletal and somatosensory systems, leading to sarcopenia and reduced postural balance, increasing the risk of falls and loss of independence. This study aimed to analyze the effects of a neuromuscular training program on postural balance, physical performance, and muscle strength in older Chilean women. Methods: The double-blind randomized controlled trial included 48 participants aged 65-80 who were divided into three groups: a control group (CG), a multicomponent training group (MCG), and a neuromuscular training group (NMG). Postural balance was assessed using a force platform with open eyes (OE) and closed eyes (CE) conditions, measuring ML velocity, AP velocity, mean radius, and area. Physical performance was evaluated with the Short Physical Performance Battery (SPPB), including static balance, 4-m walking speed, and 5× sit-to-stand chair test. Muscle strength was measured using a hydraulic hand dynamometer to record maximum grip force. Results: Significant time × group interactions in the CE condition were found for mean radius (F = 0.984; p = 0.017; ηp2 = 0.184), AP velocity (F = 10.01; p = 0.001; ηp2 = 0.312), and ML velocity (F = 4.30; p = 0.027; ηp2 = 0.163). Significant pre-post differences in the NMG for mean radius (p < 0.001), AP velocity (p < 0.001), and ML velocity (p = 0.029) were observed, with no significant changes in CG. Significant time × group interactions were also found in the SPPB test score (F = 11.49; p < 0.001; ηp2 = 0.343), gait speed (F = 5.513; p = 0.012; ηp2 = 0.198), and sit-to-stand test (F = 5.731; p = 0.010; ηp2 = 0.206), but not in the balance score (F = 2.099; p = 0.148). Handgrip strength showed no significant interactions (F = 3.216; p = 0.061; ηp2 = 0.127). Conclusions: These findings suggest that neuromuscular training is a promising intervention to mitigate the decline in balance and physical function associated with aging, offering a targeted approach to improve the quality of life in the elderly.

Support vector machine classification of patients with depression based on resting-state electroencephalography.

Depression is one of the most common mental disorders. Although depression is typically diagnosed by identifying specific symptoms and through history, no recognized standard for depression diagnosis exists. This assures the development of objective diagnostic tools for depression. We investigated the differences in the resting-state electroencephalograms (EEGs) of patients with depression and healthy controls (HCs) to distinguish patients from HCs by using a support vector machine (SVM) classifier with the following two feature selection approaches: t test and receiver operating characteristic analysis. We used the EEG data from the Patient Repository of EEG Data + Computational Tools; this study included 21 patients with depressive disorder (MDD) and 21 HCs. The relative frequency power, alpha interhemispheric asymmetry, left-right coherence, strength, clustering coefficient (CC), shortest path length, sample entropy (SampEn), multiscale entropy (MSE), and detrended fluctuation analysis (DFA) data were extracted to determine candidate EEG features associated with depression. With the t-test selection, the SVM classifier demonstrated the highest performance with the accuracy, sensitivity, and specificity of 96.66%, 95.93%, and 97.550% for the eye-open condition and 91.33%, 90.59%, and 91.81% for the eye-closed condition, respectively. For comparisons of features in the 2 selection approaches, the most influential features were relative frequency power and left-right coherence. Using this information to distinguish patients with MDD from HC subjects with the SVM classifier resulted in a mean accuracy over 90%. Although this result may not be robust enough for clinical applications, further exploration is necessary given the simplicity, objectivity, and efficiency of the classifier.

Influence of Contact Lens Parameters on Cornea: Biomechanical Analysis.

This study presents a finite element analysis to model ocular biomechanics and the interactions between the human eye and contact lenses in the closed-eye condition. The closed-eye state, where the eyelids are fully shut, presents challenges for experimental measurements due to the invasive nature of accessing and analysing the contact lens and corneal interface, making simulation tools valuable for accurate characterisation. The primary objective of this study was to examine how CLs fold and twist and their impact on the cornea when the eye is closed. The secondary aim of this study was to assess how crucial contact lens parameters (Young's modulus, base curve, and diameter) influence corneal stress distribution and the overall fit of the lens on the eye. The findings show that increasing Young's modulus significantly reduces corneal stress and promotes uniform stress distribution, making it the most influential factor for wearer comfort and safety. While base curve and diameter variations primarily affect contact area, their impact on stress distribution is minimal. This research provides insights for improving contact lens design and enhancing safety for contact lens wearers.

EEG activation in preschool children: Characteristics and predictive value for current and future mental health status

BackgroundPrevious research has characterised EEG changes associated with resting activation in primary school children and adults, while task-related activation has only been considered in adults. The current study characterises physiological activation in preschool children and examines the potential value of activation indices for predicting mental health status at two time points. AimsTo investigate how resting activation and task-related activation are represented in 4- to 5-year-old preschool children and examine if these activation indices can predict current and future mental health status. Methods and proceduresFrontal EEG was recorded from 81 preschool children during eyes-closed resting, eyes-open resting, and an inhibitory control task to allow calculation of activation indices. The Child Behaviour Checklist was completed by the child’s parent at this time, and again 6–8 months later after the child’s transition to kindergarten. Outcomes and resultsResting activation was represented by reductions in frontal delta, theta, and alpha power in the eyes-open compared to eyes-closed condition, and an increase in frontal beta power. Task-related activation was represented by increases in frontal delta, theta, and alpha power and a decrease in beta power. Frontal delta and theta task-related activation significantly predicted externalising behaviours in both preschool and kindergarten, with stronger prediction in kindergarten. Conclusions and implicationsThis study characterised resting and task-related activation in preschool children, and reported similar effects to those found in older children and adults for resting activation, with novel effects for task-related activation. As task-related activation indices were predictive of externalising behaviours in both preschool and kindergarten, these results have implications for early identification of children who experience externalising behavioural problems across the transition to school period. What does this study add?This study provides new data on how the fundamental physiological processes of resting and task-related activation, both of which are theorised to contribute to “upstream” processes such as executive functions and broader behaviour, are represented in the frontal EEG of preschool aged children. We also learn that the top-down task-related activation indices for delta and theta activity were predictive of current mental health status and future status after the transition to kindergarten, while the bottom-up resting activation indices were not.

'Knock down the brain': a nonlinear analysis of electroencephalography to study the effects of sub-concussion in boxers.

Boxing is associated with a high risk of head injuries and increases the likelihood of chronic traumatic encephalopathy. This study explores the effects of sub-concussive impacts on boxers by applying both linear and nonlinear analysis methods to electroencephalogram (EEG) data. Twenty-one boxers were selected (mean ± SD, age 28.38 ± 5.5 years; weight 67.55 ± 8.90 kg; years of activity 6.76 ± 5.45; education 14.19 ± 3.08 years) and divided into 'beginner' and 'advanced' groups. The Montreal Cognitive Assessment and the Frontal Assessment Battery were administered; EEG data were collected in both eyes-open (EO) and eyes-closed (EC) conditions during resting states. Analyses of EEG data included normalized power spectral density (nPSD), power law exponent (PLE), detrended fluctuation analysis and multiscale entropy. Statistical analyses were used to compare the groups. Significant differences in nPSD and PLE were observed between the beginner and advanced boxers, with advanced boxers showing decreased mean nPSD and PLE (nPSD 4-7 Hz, p = 0.013; 8-13 Hz, p = 0.003; PLE frontal lobe F3 EC, p = 0.010). Multiscale entropy analysis indicated increased entropy at lower frequencies and decreased entropy at higher frequencies in advanced boxers (F3 EC, p = 0.024; occipital lobe O1 EO, p = 0.029; occipital lobe O2 EO, p = 0.036). These changes are similar to those seen in Alzheimer's disease. Nonlinear analysis of EEG data shows potential as a neurophysiological biomarker for detecting the asymptomatic phase of chronic traumatic encephalopathy in boxers. This methodology could help monitor athletes' health and reduce the risk of future neurological injuries in sports.

Signal quality evaluation of an in-ear EEG device in comparison to a conventional cap system.

Wearable in-ear electroencephalographic (EEG) devices hold significant promise for integrating brain monitoring technologies into real-life applications. However, despite the introduction of various in-ear EEG systems, there remains a necessity for validating these technologies against gold-standard, clinical-grade devices. This study aims to evaluate the signal quality of a newly developed mobile in-ear EEG device compared to a standard scalp EEG system among healthy volunteers during wakefulness and sleep. The study evaluated an in-ear EEG device equipped with dry electrodes in a laboratory setting, recording a single bipolar EEG channel using a cross-ear electrode configuration. Thirty healthy participants were recorded simultaneously using the in-ear EEG device and a conventional EEG cap system with 64 wet electrodes. Based on two recording protocols, one during a resting state condition involving alternating eye opening and closure with a low degree of artifact contamination and another consisting of a daytime nap, several quality measures were used for a quantitative comparison including root mean square (RMS) analysis, artifact quantification, similarities of relative spectral power (RSP), signal-to-noise ratio (SNR) based on alpha peak criteria, and cross-signal correlations of alpha activity during eyes-closed conditions and sleep activities. The statistical significance of our results was assessed through nonparametric permutation tests with False Discovery Rate (FDR) control. During the resting state, in-ear and scalp EEG signals exhibited similar fluctuations, characterized by comparable RMS values. However, intermittent signal alterations were noticed in the in-ear recordings during nap sessions, attributed to movements of the head and facial muscles. Spectral analysis indicated similar patterns between in-ear and scalp EEG, showing prominent peaks in the alpha range (8-12 Hz) during rest and in the low-frequency range during naps (particularly in the theta range of 4-7 Hz). Analysis of alpha wave characteristics during eye closures revealed smaller alpha wave amplitudes and slightly lower signal-to-noise ratio (SNR) values in the in-ear EEG compared to scalp EEG. In around 80% of cases, cross-correlation analysis between in-ear and scalp signals, using a contralateral bipolar montage of 64 scalp electrodes, revealed significant correlations with scalp EEG (p < 0.01), particularly evident in the FT11-FT12 and T7-T8 electrode derivations. Our findings support the feasibility of using in-ear EEG devices with dry-contact electrodes for brain activity monitoring, compared to a standard scalp EEG, notably for wakefulness and sleep uses. Although marginal signal degradation is associated with head and facial muscle contractions, the in-ear device offers promising applications for long-term EEG recordings, particularly in scenarios requiring enhanced comfort and user-friendliness.

Prefrontal, Frontal, and Temporal Theta EEG Asymmetries and Self-Reports of Emotional Regulation.

Previous studies have shown thatright-sided frontal alpha asymmetry (fAA) is an electroencephalography (EEG) marker for negatively valenced emotions and a marker for negative self-perceptions of a person's psychosocial interactions. Alpha activity is affected by the changes in visual stimulation associated with eye-opening and eye-closing; theta activity is not so affected. Therefore, this analysis investigates the relationship between an individual's theta asymmetry and self-perceptions of their psychosocial interactions. We used quantitative electroencephalographic (qEEG) data from eight right-handed male medical students aged between 19 and 38 years, recorded under eyes-open (EO) and eyes-closed (EC) conditions. Significant correlations were found between self-reported measures of psychosocial interactions via the Interactive Self-Report Inventory (ISI). The main finding was that greater left-sided frontal temporal asymmetry (fTA) under both EO and EC conditions was associated with lower "regulated" ISI scores and lower "dependent" ISI scores. Greater left-sided temporal theta asymmetry (tTA), under EC conditions, was associated with higher "anxious" ISI scores. Greater left-sided prefrontal theta symmetry (pfTA), under EO conditions, was associated with lower "relaxed" ISI scores. These findings suggest that theta asymmetries in the frontal, prefrontal, and temporal cortices may be indicative of negative emotional states. The results of this study underscore the potential of pfTA, fTA, and tTA to be used as biomarkers for cognitive-emotional balance. The implications for mental health interventions, particularly personalized therapeutic approaches, are significant.