Increase In Alpha Power Research Articles

Comparison of power spectra from overnight electroencephalography between patients with Down syndrome and matched control subjects.

Electroencephalograms can capture brain oscillatory activities during sleep as a form of electrophysiological signals. We analysed electroencephalogram recordings from full-night in-laboratory polysomnography from 100 patients with Down syndrome, and 100 age- and sex-matched controls. The ages of patients with Down syndrome spanned 1 month to 31 years (median 4.4 years); 84 were younger than 12 years, and 54 were male. From each electroencephalogram, we extracted relative power in six frequency bands or rhythms (delta, theta, alpha, slow sigma, fast sigma, and beta) from six channels (frontal F3 and F4, central C3 and C4, and occipital O1 and O2) during five sleep stages (N3, N2, N1, R and W)-180 features in all. We examined differences in relative power between Down syndrome and control electroencephalograms for each feature separately. During wake and N1 sleep stages, alpha rhythms (8.0-10.5 Hz) had significantly lower power in patients with Down syndrome than controls. Moreover, the rate of increase in alpha power with age during rapid eye movement sleep was significantly slower in Down syndrome than control subjects. During wake and N1 sleep, delta rhythms (0.25-4.5 Hz) had higher power in patients with Down syndrome than controls. During N2 sleep, slow sigma rhythms (10.5-12.5 Hz) had lower power in patients with DS than controls. These findings extend previous research from routine electroencephalogram studies demonstrating that patients with Down syndrome had reduced circadian amplitude-the difference between wake alpha power and deep sleep delta power was smaller in Down syndrome than control subjects. We envision that these brain oscillatory activities may be used as surrogate markers for clinical trials for patients with Down syndrome.

Alpha modulation via transcranial alternating current stimulation in adults with attention-deficit hyperactivity disorder.

One potential therapy treating attention-deficit/hyperactivity disorder (ADHD) is to modulate dysfunctional brain activations using brain stimulation techniques. While the number of studies investigating the effect of transcranial direct current stimulation on ADHD symptoms continues to increase, transcranial alternating current stimulation (tACS) is poorly examined. Previous studies reported impaired alpha brain oscillation (8-12 Hz) that may be associated with increased attention deficits in ADHD. Our aim was to enhance alpha power in adult ADHD patients via tACS, using different methods to explore potential therapeutic effects. Undergoing a crossover design, adults with ADHD received active and sham stimulation on distinct days. Before and after each intervention, mean alpha power, attention performance, subjective symptom ratings, as well as head and gaze movement were examined. Frequency analyses revealed a significant power increase in the alpha band after both interventions. Despite a trend toward an interaction effect, this alpha power increase was, however, not significantly higher after active stimulation compared to sham stimulation. For the other measures, some additional pre-post effects were found, which were not intervention-related. Our study cannot provide clear evidence for a tACS-induced increase in alpha power in adult ADHD patients, and thus no stimulation related improvement of attention parameters. We provide further recommendations for the future investigation of tACS as a potential ADHD treatment.

In Utero Exposure to Alcohol and Tobacco and Electroencephalogram Power During Childhood

Prenatal alcohol exposure (PAE) and prenatal tobacco exposure (PTE) are risk factors associated with adverse neurobehavioral and cognitive outcomes. To quantify long-term associations of PAE and PTE with brain activity in early and middle childhood via electroencephalography (EEG). This cohort study included participants enrolled in the Safe Passage Study (August 2007 to January 2015), from which a subset of 649 participants were followed up in the Environmental Influences on Child Health Outcomes Program. From September 2018 through November 2022, EEG recordings were obtained at ages 4, 5, 7, 9, or 11 years. Data were analyzed from November 2022 to November 2023. Maternal self-reported consumptions of alcohol and tobacco during pregnancy were captured at the recruitment interview and at up to 3 visits during pregnancy (20-24, 28-32, and ≥34 weeks' gestation). Classifications of PAE (continuous drinking, quit-early drinking, and nondrinking) and PTE (continuous smoking, quit-early smoking, and nonsmoking) were previously obtained. EEG band powers (theta, alpha, beta, gamma) were extracted from the EEG recordings. Linear regression models were used to estimate the associations of PAE and PTE with EEG estimates. The final sample included 649 participants (333 [51.3%] female) aged 4, 5, 7, 9, or 11 years. Children whose mothers were in the quit-early drinking cluster had increased alpha power (0.116 [95% CI, 0.023 to 0.209] μV2; P = .02) compared with individuals without PAE. The magnitude of this increase was approximately double for children exposed to continuous drinking (0.211 [95% CI, 0.005 to 0.417] μV2; P = .04). Children whose mothers were in the continuous smoking cluster had decreased beta power (-0.031 [95% CI, -0.059 to -0.003] μV2; P = .03) and gamma power (-0.020 [95% CI, -0.039 to -0.000] μV2; P = .04) compared with the nonsmoking cluster. In exploratory sex-stratified models, male participants in the quit-early PAE cluster had greater EEG power in the alpha band (0.159 [95% CI, 0.003 to 0.315] μV2; P = .04) compared with those with no PAE, and the difference was approximately double for male participants with continuous PAE (0.354 [95% CI, 0.041 to 0.667] μV2; P = .03). Male participants in the continuous PTE cluster had decreased beta (-0.048 [95% CI, -0.090 to - 0.007] μV2; P = .02) and gamma (-0.032 [95% CI, -0.061 - 0.002] μV2; P = .04) power compared with those with no PTE. These findings suggest that even low levels of PAE and PTE were associated with long-term alterations of brain activity.

Amphetamine increases motivation of humans and mice as measured by breakpoint, but does not affect an Electroencephalographic biomarker.

Translation of drug targets from preclinical studies to clinical trials has been aided by cross-species behavioral tasks, but evidence for brain-based engagement during task performance is still required. Cross-species progressive ratio breakpoint tasks (PRBTs) measure motivation-related behavior and are pharmacologically and clinically sensitive. We recently advanced elevated parietal alpha power as a cross-species electroencephalographic (EEG) biomarker of PRBT engagement. Given that amphetamine increases breakpoint in mice, we tested its effects on breakpoint and parietal alpha power in both humans and mice. Twenty-three healthy participants performed the PRBT with EEG after amphetamine or placebo in a double-blind design. C57BL/6J mice were trained on PRBT with EEG (n = 24) and were treated with amphetamine or vehicle. A second cohort of mice was trained on PRBT without EEG (n = 40) and was treated with amphetamine or vehicle. In humans, amphetamine increased breakpoint. In mice, during concomitant EEG, 1 mg/kg of amphetamine significantly decreased breakpoint. In cohort 2, however, 0.3 mg/kg of amphetamine increased breakpoint consistent with human findings. Increased alpha power was observed in both species as they reached breakpoint, replicating previous findings. Amphetamine did not affect alpha power in either species. Amphetamine increased effort in humans and mice. Consistent with previous reports, elevated parietal alpha power was observed in humans and mice as they performed the PRBT. Amphetamine did not affect this EEG biomarker of effort. Hence, these findings support the pharmacological predictive validity of the PRBT to measure effort in humans and mice and suggest that this EEG biomarker is not directly reflective of amphetamine-induced changes in effort.

Changes in Mental Health and EEG Biomarkers of Undergraduates Under Different Patterns of Mindfulness.

The effects of short-term mindfulness are associated with the different patterns (autonomic, audio guided, or experienced and certified mindfulness instructor guided mindfulness). However, robust evidence for reported the impacts of different patterns of mindfulness on mental health and EEG biomarkers of undergraduates is currently lacking. Therefore, we aimed to test the hypotheses that mindfulness training for undergraduates would improve mental health, and increase alpha power over frontal region and theta power over midline region at the single electrode level. We also describe the distinction among frequency bands patterns in different sites of frontal and midline regions. 70 participants were enrolled and assigned to either 5-day mindfulness or a waiting list group. Subjective questionnaires measured mental health and other psychological indicators, and brain activity was recorded during various EEG tasks before and after the intervention. The 5-day mindfulness training improved trait mindfulness, especially observing (p = 0.001, d = 0.96) and nonreactivity (p = 0.03, d = 0.56), sleep quality (p = 0.001, d = 0.91), and social support (p = 0.001, d = 0.95) while not in affect. Meanwhile, the expected increase in the alpha power of frontal sites (p < 0.017, d > 0.84) at the single electrode level was confirmed by the current data rather than the theta. Interestingly, the alteration of low-beta power over the single electrode of the midline (p < 0.05, d > 0.71) was difference between groups. Short-term mindfulness improves practitioners' mental health, and the potentially electrophysiological biomarkers of mindfulness on neuron oscillations were alpha activity over frontal sites and low-beta activity over midline sites.

A study on neural changes induced by sauna bathing: Neural basis of the "totonou" state.

Saunas are becoming increasingly popular worldwide, being an activity that promotes relaxation and health. Intense feelings of happiness have been reported shortly after enjoying a hot sauna and cold water, what is known in Japan as the "totonou" state. However, no research has investigated what occurs in the brain during the "totonou" state. In the present study, participants underwent a sauna phase, consisting of three sets of alternating hot sauna, cold water, and rest. We elucidated changes in brain activity and mood in the "totonou" state by measuring and comparing brain activity and emotional scales before and after the sauna phase and during the rest phase in each set. We found significant increases in theta and alpha power during rest and after the sauna phase compared to before the sauna phase. Moreover, in an auditory oddball task, the p300 amplitude decreased significantly and MMN amplitude increased significantly after the sauna phase. The increase in MMN indicates higher activation of the pre-attentional auditory process, leading to a decrease in attention-related brain activity P300. Hence, the brain reaches in a more efficient state. Further, the response time in behavioral tasks decreased significantly. In addition, the participants' subjective responses to the questionnaire showed significant changes in physical relaxation and other indicators after being in the sauna. Finally, we developed an artificial intelligence classifier, obtaining an average accuracy of brain state classification of 88.34%. The results have potential for future application.

Evaluating the impact of water reuse educational videos on water reuse perceptions using EEG/event related potential

As climate change and population growth increasingly stress freshwater resources, government agencies and scientists have recognized the importance of water reuse (the beneficial use of reclaimed or recycled water). While end users (municipalities and farmers) are largely open to exploring water reuse, a barrier to using this water source is the public's negative perception, or the ‘yuck factor’. Recognizing that water reuse is becoming a necessity, there is an urgent need to determine how to improve public acceptance of this water source. Increasing knowledge has been identified as a critical method for improving the adoption of sustainable practices, but to date, there has been a lack of outcome studies on the ability of water reuse education materials to change perceptions. Previous studies have relied heavily on self-reported concerns and perceptions which are limited by bias and social expectations, and their results have failed to substantially change water reuse education efforts, and by extension failed to substantially improve water reuse perceptions. We propose the integration of psychology for evaluating the effectiveness of water reuse education and outreach efforts. The purpose of this study was to determine if water reuse educational videos modulate perceptions of water reuse terms. Participants were recruited from a university campus and completed pre-intervention surveys on water reuse knowledge, willingness to use recycled water, and preferred water reuse information sources. We then measured changes in neural activity in response to multiple categories of water reuse terms pre- and post-exposure to water reuse education videos using electroencephalogram (EEG). Through EEG we measured event related potential (ERP), which assesses sustained engagement with the cues (late positive potential (LPP) amplitude), and alpha power. Participants also completed a pre/post exposure battery involving five tasks, in randomized order, presented before and after viewing videos. Sixty-eight percent of survey participants had previously heard of water reuse and 91% reported willingness to use recycled water for at least one activity. Participants reported obtaining water reuse information mostly from the internet (77%) and preferred to receive additional information mainly by watching online videos (73%). We observed significant increases in alpha power, corresponding to feelings of relaxation, in response to seven of eight water reuse term categories post-video exposure. These findings show that water reuse educational videos can change perceptions of water reuse. Our results point to the possibility of validating and increasing the effectiveness of water reuse education materials using sophisticated neurocognitive measures.

Medication-invariant resting aperiodic and periodic neural activity in Parkinson's disease.

Parkinson's disease (PD) has been associated with greater total power in canonical frequency bands (i.e., alpha, beta) of the resting electroencephalogram (EEG). However, PD has also been associated with a reduction in the proportion of total power across all frequency bands. This discrepancy may be explained by aperiodic activity (exponent and offset) present across all frequency bands. Here, we examined differences in the eyes-open (EO) and eyes-closed (EC) resting EEG of PD participants (N = 26) on and off medication, and age-matched healthy controls (CTL; N = 26). We extracted power from canonical frequency bands using traditional methods (total alpha and beta power) and extracted separate parameters for periodic (parameterized alpha and beta power) and aperiodic activity (exponent and offset). Cluster-based permutation tests over spatial and frequency dimensions indicated that total alpha and beta power, and aperiodic exponent and offset were greater in PD participants, independent of medication status. After removing the exponent and offset, greater alpha power in PD (vs. CTL) was only present in EO recordings and no reliable differences in beta power were observed. Differences between PD and CTL in the resting EEG are likely driven by aperiodic activity, suggestive of greater relative inhibitory neural activity and greater neuronal spiking. Our findings suggest that resting EEG activity in PD is characterized by medication-invariant differences in aperiodic activity which is independent of the increase in alpha power with EO. This highlights the importance of considering aperiodic activity contributions to the neural correlates of brain disorders.

EEG Biofeedback Decreases Theta and Beta Power While Increasing Alpha Power in Insomniacs: An Open-Label Study.

Insomnia, often associated with anxiety and depression, is a prevalent sleep disorder. Biofeedback (BFB) treatment can help patients gain voluntary control over physiological events such as by utilizing electroencephalography (EEG) and electromyography (EMG) power. Previous studies have rarely predicted biofeedback efficacy by measuring the changes in relative EEG power; therefore, we investigated the clinical efficacy of biofeedback for insomnia and its potential neural mechanisms. We administered biofeedback to 82 patients with insomnia, of whom 68 completed 10 sessions and 14 completed 20 sessions. The average age of the participants was 49.38 ± 12.78 years, with 26 men and 56 women. Each biofeedback session consisted of 5 min of EMG and 30 min of EEG feedback, with 2 min of data recorded before and after the session. Sessions were conducted every other day, and four scale measures were taken before the first, fifth, and tenth sessions and after the twentieth session. After 20 sessions of biofeedback treatment, scores on the Pittsburgh Sleep Quality Index (PSQI) were significantly reduced compared with those before treatment (-5.5 ± 1.43,t = -3.85, p = 0.006), and scores on the Beck Depression Inventory (BDI-II) (-7.15 ± 2.43, t = -2.94, p = 0.012) and the State-Trait Anxiety Inventory (STAI) (STAI-S: -12.36 ± 3.40, t = -3.63, p = 0.003; and STAI-T: -9.86 ± 2.38, t = -4.41, p = 0.001) were significantly lower after treatment than before treatment. Beta and theta power were significantly reduced after treatment, compared with before treatment (F = 6.25, p = 0.014; and F = 11.91, p = 0.001). Alpha power was increased after treatment, compared with before treatment, but the difference was not prominently significant (p > 0.05). EMG activity was significantly decreased after treatment, compared with before treatment (F = 2.11, p = 0.015). Our findings suggest that BFB treatment based on alpha power and prefrontal EMG relieves insomnia as well as anxiety and depression and may be associated with increased alpha power, decreased beta and theta power, and decreased EMG power.

The Experience of Meaningful Coincidences Is Associated with Stronger Alpha Power Increases during an Eyes-closed Resting Condition: A Bayesian Replication Approach.

Recognizing and perceiving meaningful patterns in an ever-changing environment is fundamental to (human) beings. Apophenia, patternicity, and the propensity to perceive meaningful coincidences might result from the human brain working as a prediction machine that constantly matches sensory information to prior expectations. The propensity for Type I errors varies between people and, at its extreme, is associated with symptoms of schizophrenia. However, on a nonclinical level seeing meaning in randomness might be benevolent and was found to be associated with creativity and openness. However, hardly any neuroscientific investigation has examined EEG patterns of the propensity to experience meaningful coincidences in this manner. We hypothesized deviations in brain functions as one potential reason why some people experience more meaning in random arrangements than others. The gating by inhibition theory suggests that alpha power increases represent basic control mechanisms of sensory processes during varying task requirements. We found that people perceiving more meaningful coincidences had higher alpha power during an eyes-closed versus eyes-opened condition compared with people experiencing less meaningful coincidences. This indicates deviations in the sensory inhibition mechanism of the brain, which are critically relevant for higher cognitive functions. Applying Bayesian statistics, we replicated this finding in another independent sample.

Immature event-related alpha dynamics in children compared with the young adults during inhibition shown by day-night stroop task.

Inhibitory control develops gradually from infancy to childhood and improves further during adolescence as the brain matures. Related previous studies showed the indispensable role of task-related alpha power during inhibition both in children and young adults. Nonetheless, none of the studies have been able to investigate the direct differences in brain responses between children and young adults when confronted with a stimulus that should be inhibited. Because, unlike event-related designs, task-related designs involve continuous tasks over a certain period, which precludes the possibility of making such a comparison. Accordingly, by employing event-related design, the present study first time in the literature, aimed to analyze the event-related alpha phase locking and event-related alpha synchronization/ desynchronization to differentiate the inhibitory processes in children compared to young adults. Twenty children between the ages of 6 to 7 years and 20 healthy young adult subjects between the ages of 18 to 30 years were included in the study. Day-night Stroop task was applied to all subjects during 18-channel EEG recordings. Event-related time-frequency analysis was performed with the complex Morlet Wavelet Transform for the alpha frequency band (8-13 Hz). Event related spectral perturbation (ERSP) in three different time windows (0-200 ms, 200-400 ms, 400-600 ms) and Event-related phase locking in the early time window (0-400 ms) was calculated. The children had increased alpha power in early and late time windows but decreased alpha phase locking in the early time windows compared to young adults. There were also topological differences between groups; while young adults had increased alpha phase-locking in frontal and parietal electrode sites, children had increased occipital alpha power and phase locking. The shift in event-related alpha power observed from posterior to anterior regions with age may suggest a progressive maturation of the frontal areas involved in inhibitory processes from childhood to adulthood. The results of the present study showed that children and young adults had different EEG oscillatory dynamics during inhibitory processes at alpha frequency range.

Attention-related power and functional connectivity modulation associated with long-term alpha neurofeedback training

Electroencephalography (EEG) based Neurofeedback training (NFT) is a non-invasive, brain-modulation technique that can improve the subject’s attention. In this research, the effectiveness of long-term NFT on the subject’s attention is explored. Real-time frontal lobe alpha band (8–13 Hz) power was used as feedback. The subjects were divided into the NFT group (n = 25) which received training and the control group (n = 25) which did not. All the subjects participated in the attention network task (ANT) at three stages i.e., before, mid, and at the end of NFT sessions. The EEG and behavioral data (Response time (RT) of the ANT task) were recorded for all subjects. The EEG data were pre-processed using a manual artifact removal procedure to avoid event-related information loss. Alpha band modulation can affect other bands such as theta (4–8 Hz) and beta (13–30 Hz) hence event-related functional connectivity (FC) and band power (BP) were analyzed in these bands as well. In event-related analysis, a significant increase (ANOVA & T-Test: P < 0.05) in theta and alpha power and FC within the NFT group was observed after NFT sessions whereas the changes observed within the control group were not significant. The RT of the subjects in the NFT group decreased. The increase in event-related power and connectivity within the theta and alpha band and the decrease in RT in the NFT group indicate the effectiveness of NFT sessions in the enhancement of attention.

Frontal EEG alterations induced by hippocampal amyloid pathology in rats

PurposeIn this study, it was aimed to determine the dose-dependent effects of hippocampal amyloid beta (Aβ) on frontal EEG activity and to elucidate the possible non-invasive biomarkers by recording spontaneous EEG in free-moving rats. Material and methodsMale albino Wistar rats aged 3 months were randomly divided into 4 groups (n ​= ​8 for each group), obtained by intrahippocampal injection of saline or different doses of Aβ1-42 i.e. 0.01 ​μg/μl, 0.1 ​μg/μl, and 1 ​μg/μl. After two weeks of recovery period, spontaneous EEG recordings were obtained from frontal regions and spectral power analyses were performed. ResultsWe detected a general slowdown in the brain activity two weeks after Aβ1-42 injection.We observed significant increases in frontal alpha power (p ​= ​0.0021) and significant decreases in frontal beta power (p ​= ​0.0003) between the Sh and Aβ1-42-injected groups. More specifically, the ratio of the frontal EEG beta and alpha power (rFBA) was significantly affected by the intrahippocampal injection of Aβ1-42 (p ​< ​0.0001). Also, we observed that rFBA was negatively and strongly correlated with hippocampal Aβ1-42 peptide levels (r ​= ​−0.781, p ​< ​0.0001). ConclusionOur findings indicate that spontaneous frontal EEG beta and alpha activity were significantly affected by the intrahippocampal injection of Aβ1-42. However, the results suggest that the power ratios of these bands are more sensitive to the hippocampal amyloid pathology. As such, it is proposed that the rFBA may be a more effective biomarker for diagnosing hippocampal pathology induced by Aβ1-42.

Understanding the effects of cortical gyrification in tACS: insights from experiments and computational models.

The alpha rhythm is often associated with relaxed wakefulness or idling and is altered by various factors. Abnormalities in the alpha rhythm have been linked to several neurological and psychiatric disorders, including Alzheimer's disease. Transcranial alternating current stimulation (tACS) has been proposed as a potential tool to restore a disrupted alpha rhythm in the brain by stimulating at the individual alpha frequency (IAF), although some research has produced contradictory results. In this study, we applied an IAF-tACS protocol over parieto-occipital areas to a sample of healthy subjects and measured its effects over the power spectra. Additionally, we used computational models to get a deeper understanding of the results observed in the experiment. Both experimental and numerical results showed an increase in alpha power of 8.02% with respect to the sham condition in a widespread set of regions in the cortex, excluding some expected parietal regions. This result could be partially explained by taking into account the orientation of the electric field with respect to the columnar structures of the cortex, showing that the gyrification in parietal regions could generate effects in opposite directions (hyper-/depolarization) at the same time in specific brain regions. Additionally, we used a network model of spiking neuronal populations to explore the effects that these opposite polarities could have on neural activity, and we found that the best predictor of alpha power was the average of the normal components of the electric field. To sum up, our study sheds light on the mechanisms underlying tACS brain activity modulation, using both empirical and computational approaches. Non-invasive brain stimulation techniques hold promise for treating brain disorders, but further research is needed to fully understand and control their effects on brain dynamics and cognition. Our findings contribute to this growing body of research and provide a foundation for future studies aimed at optimizing the use of non-invasive brain stimulation in clinical settings.

Time-locked acute alpha-frequency stimulation of subthalamic nuclei during the evaluation of emotional stimuli and its effect on power modulation.

Deep brain stimulation (DBS) studies in Parkinson's Disease (PD) targeting the subthalamic nucleus (STN) have characterized its spectral properties across cognitive processes. In emotional evaluation tasks, specific alpha frequency (8-12 Hz) event-related de-synchronization (ERD) (reduced power) has been demonstrated. The time-locked stimulation of STN relative to stimuli onset has shown subjective positive valence shifts with 10 Hz but not with 130 Hz. However, neurophysiological effects of stimulation on power modulation have not been investigated. We aim to investigate effects of acute stimulation of the right STN on concurrent power modulation in the contralateral STN and frontal scalp EEG. From our previous study, we had a strong a priori hypothesis that negative imagery without stimulation would be associated with alpha ERD; negative imagery with 130 Hz stimulation would be also associated with alpha ERD given the lack of its effect on subjective valence ratings; negative imagery with 10 Hz stimulation was to be associated with enhanced alpha power given the shift in behavioral valence ratings. Twenty-four subjects with STN DBS underwent emotional picture-viewing tasks comprising neutral and negative pictures. In a subset of these subjects, the negative images were associated with time-locked acute stimulation at either 10 or 130 Hz. Power of signals was estimated relative to the baseline and subjected to non-parametric statistical testing. As hypothesized, in 130 Hz stimulation condition, we show a decrease in alpha power to negative vs. neutral images irrespective of stimulation. In contrast, this alpha power decrease was no longer evident in the negative 10 Hz stimulation condition consistent with a predicted increase in alpha power. Greater beta power in the 10 Hz stimulation condition along with correlations between beta power across the 10 Hz stimulation and unstimulated conditions suggest physiological and cognitive generalization effects. Acute alpha-specific frequency stimulation presumably was associated with a loss of this expected decrease or desynchronization in alpha power to negative images suggesting the capacity to facilitate the synchronization of alpha and enhance power. Acute time-locked stimulation has the potential to provide causal insights into the spectral frequencies and temporal dynamics of emotional processing.

Effect of alpha range activity on SSVEP decoding in brain-computer interfaces.

Brain-computer interfaces (BCIs) facilitate direct communication between the brain and external devices. For BCI technology to be commercialized for wide scale applications, BCIs should be accurate, efficient, and exhibit consistency in performance for a wide variety of users. A core challenge is the physiological and anatomical differences amongst people, which causes a high variability amongst participants in BCI studies. Hence, it becomes necessary to analyze the mechanisms causing this variability and address them by improving the decoding algorithms. In this paper, a publicly available steady-state visual evoked potential (SSVEP) dataset is analyzed to study the effect of SSVEP flicker on the endogenous alpha power and the subsequent overall effect on the classification accuracy of the participants. It was observed that the participants with classification accuracy below 95% showed increased alpha power in their brain activities. Incorrect prediction in the decoding algorithm was observed a maximum number of times when the predicted frequency was in the range 9-12 Hz. We conclude that frequencies between 9-12 Hz may result in below par performance in some participants when canonical correlation analysis is used for classification.Clinical relevance-If alpha-band frequencies are used for SSVEP stimulation, alpha power interference in EEG may alter BCI accuracy for some users.

Alpha oscillations protect working memory against distracters in a modality-specific way

Alpha oscillations are thought to be involved in suppressing distracting input in working-memory tasks. Yet, the spatial-temporal dynamics of such suppression remain unclear. Key questions are whether such suppression reflects a domain-general inattentiveness mechanism, or occurs in a stimulus- or modality-specific manner within cortical areas most responsive to the distracters; and whether the suppression is proactive (i.e., preparatory) or reactive. Here, we addressed these questions using a working-memory task where participants had to memorize an array of visually presented digits and reproduce one of them upon being probed. We manipulated the presence of distracters and the sensory modality in which distracters were presented during memory maintenance. Our results show that sensory areas most responsive to visual and auditory distracters exhibited stronger alpha power increase after visual and auditory distracter presentation respectively. These results suggest that alpha oscillations underlie distracter suppression in a reactive, modality-specific manner.

The potential role of GSK-3β signaling pathway for amelioration actions of ketamine on the PTSD rodent model

RationalePost-traumatic stress disorder (PTSD) is a complex, chronic psychiatric disorder typically triggered by life-threatening events and, as yet, lacks a specialized pharmacological treatment. The potential therapeutic role of ketamine, an N-methyl-D-aspartate receptor antagonist, in mitigating PTSD has been the subject of investigation. ObjectiveThe aim of this study was to elucidate alterations in the glycogen synthase kinase-3β (GSK-3β) signaling pathway in response to ketamine intervention, using the single prolonged stress (SPS) model of PTSD at a molecular level. MethodsPTSD-like symptoms were simulated using the SPS model. Ketamine (10 mg/kg) and GSK-3β antagonist SB216763 (5 mg/kg) were then administered intraperitoneally. Stress-related behavior was evaluated through the open field test (OFT) and the elevated plus maze test (EMPT). Additionally, brain activity was analyzed using quantitative electroencephalography (qEEG). Changes in protein and mRNA expressions of glucocorticoid receptor (GR), brain-derived neurotrophic factor (BDNF), GSK-3β, phosphorylated ser-9 GSK-3β (p-GSK-3β), FK506 binding protein 5 (FKBP5), and corticotropin-releasing hormone (CRH) were assessed in the hypothalamus via western blot and qPCR. ResultsSPS-exposed rats exhibited reduced distance and time spent in the center of the open arms, a pattern divergent from control rats. qEEG readings revealed SPS-induced increases in alpha power, low gamma and high gamma power. Furthermore, SPS triggered an upregulation in the protein and gene expression of GSK-3β, GR, BDNF, p-GSK-3β, and FKBP5, and downregulated CRH expression in the hypothalamus. Ketamine administration following the SPS procedure counteracted these changes by increasing the time spent in the center of the OFT, the distance traversed in the open arms of the EMPT, and mitigating SPS-induced alterations in cerebral cortex oscillations. Moreover, ketamine reduced the protein levels of GSK-3β, GR, p-GSK-3β, and altered the ratio of p-GSK-3β to GSK-3β. Gene expression of GSK-3β, GR, BDNF, and FKBP5 decreased in the SPS-Ket group compared to the SPS-Sal group. ConclusionsKetamine appeared to remediate the abnormal GSK-3β signaling pathway induced by SPS. These findings collectively suggest that ketamine could be a promising therapeutic agent for PTSD symptoms, working through the modulation of the GSK-3β signaling pathway.

Effects of acute psychosocial stress on source level EEG power and functional connectivity measures

The usage of EEG to uncover the influence of psychosocial stressors (PSSs) on neural activity has gained significant attention throughout recent years, but the results are often troubled by confounding stressor types. To investigate the effect of PSSs alone on neural activity, we employed a paradigm where participants are exposed to negative peer comparison as PSS, while other possible stressors are kept constant, and compared this with a condition where participants received neutral feedback. We analyzed commonly used sensor level EEG indices (frontal theta, alpha, and beta power) and further investigated whether source level power and functional connectivity (i.e., the temporal dependence between spatially seperated brain regions) measures, which have to our knowledge not yet been used, are more sensitive to PSSs than sensor level-derived EEG measures. Our results show that on sensor level, no significant frontal power changes are present (all p’s > 0.16), indicating that sensor level frontal power measures are not sensitive enough to be affected by only PSSs. On source level, we find increased alpha power (indicative of decreased cortical activity) in the left- and right precuneus and right posterior cingulate cortex (all p’s < 0.03) and increased functional connectivity between the left- and right precuneus (p < 0.001), indicating that acute, trial based PSSs lead to decreased precuneus/PCC activity, and possibly indicates a temporary disruption in the self-referential neural processes of an individual.

0036 ARC Genotype Modulates REM EEG Spectral Power Following Total Sleep Deprivation

Abstract Introduction EEG spectral power in the alpha range is indicative of a wake-like state, with alpha power typically high during wakefulness and reduced during sleep. We previously reported that a single nucleotide polymorphism (SNP) of the activity-regulated cytoskeleton associated protein (ARC) gene modulates non-REM theta and alpha spectral power. Here we sought to determine whether ARC genotype is also associated with phenotypic differences in EEG spectral power during REM sleep. Methods 43 healthy adults (27.6±4.8y; 23 females) participated in one of two in-laboratory studies. Each participant had a 10h baseline sleep opportunity (22:00–08:00), 38h TSD, and 10h recovery sleep opportunity (22:00–08:00). Sleep periods were recorded polysomnographically and visually scored according to AASM criteria. Genomic DNA was assayed for the ARC c.*742 + 58C&amp;gt;T non-coding SNP, rs35900184. Log-transformed EEG spectral power (C3-M3 derivation) for REM sleep over 0.2 Hz frequency bins in each of four frequency bands – delta (0.8–4.0 Hz), theta (4.2–8.0 Hz), alpha (8.2–12.0 Hz), and beta (12.2–16.0 Hz) – was analyzed by band using mixed-effects ANOVA with fixed effects for ARC genotype, night (baseline, recovery), frequency bin, and their interactions. Analyses included study and age as covariates and a random effect over subjects on the intercept. Results The genotype distribution in this sample was 28 C/C homozygotes, 10 C/T heterozygotes, and 5 T/T homozygotes. There was a significant genotype by night interaction in the alpha band (F2,1560=23.80, p&amp;lt; 0.001). Compared to baseline sleep, T/T homozygotes had 13.0% more alpha power during post-TSD recovery sleep, whereas C/C homozygotes had 1.2% less alpha power and C/T heterozygotes had 3.2% less alpha power. This differential TSD effect for the ARC genotypes was not seen in the other spectral bands. Conclusion Our results show that ARC genotype mediates the REM sleep EEG response to TSD, with T/T homozygotes displaying a pronounced increase in REM alpha power following sleep deprivation. The ARC SNP has been associated with schizophrenia, a psychiatric disorder with known sleep disturbances. As such, the ARC-mediated increase in REM EEG alpha power for T/T homozygotes might be a marker of a psychosis-like predisposition. Support (if any) ONR N00014-13-1-0302; NIH R21CA167691; USAMRDC W81XWH-18-1-0100; ARO W911NF2210223