Individual Alpha Peak Frequency Research Articles

Individual posterior alpha rhythms and cognitive reserve as possible early prognostic markers in people with subjective memory complaints

Subjective memory complaints (SMCs) are a memory disorder that often precedes mild cognitive impairment (MCI) or Alzheimer’s disease (AD). Both individual alpha rhythms and cognitive reserve (CR) represent key features of SMCs and provide useful tools to characterize and predict the course of the disorder. We studied whether older people with SMCs may also present some abnormal resting state electroencephalogram (rsEEG) alpha rhythms, and whether alpha rhythms are associated with CR. To do this, eyes-closed rsEEG were recorded in 68 older people with and without SMCs. The individual alpha indexes alpha/theta transition frequency (TF) and individual alpha frequency peak (IAFp) were computed. TF and IAFp were also used to determine the alpha1, alpha2, and alpha3 power frequency. Results indicated no differences in TF or IAFp between older people with SMCs and controls. The SMCs group showed a reduction in alpha3 power in comparison with controls. Specifically, women with SMCs were characterized by a significant decrease in alpha3 power compared to control women. Furthermore, only in SMCs group, greater CR was associated with slow IAFp. In sum, these results suggest that TF and IAFp are two stable indexes that are not influenced by the presence of SMCs. However, the reduction in alpha3, as observed in women with SMCs, shows an abnormal posterior rsEEG at alpha power. Finally, the compensatory mechanisms of CR appear to interact with the neurophysiological mechanisms that underlie the regulation of alpha rhythms.

Aperiodic component of EEG power spectrum and cognitive performance are modulated by education in aging

Recent studies have shown a growing interest in the so-called “aperiodic” component of the EEG power spectrum, which describes the overall trend of the whole spectrum with a linear or exponential function. In the field of brain aging, this aperiodic component is associated both with age-related changes and performance on cognitive tasks. This study aims to elucidate the potential role of education in moderating the relationship between resting-state EEG features (including aperiodic component) and cognitive performance in aging. N = 179 healthy participants of the “Leipzig Study for Mind–Body-Emotion Interactions” (LEMON) dataset were divided into three groups based on age and education. Older adults exhibited lower exponent, offset (i.e. measures of aperiodic component), and Individual Alpha Peak Frequency (IAPF) as compared to younger adults. Moreover, visual attention and working memory were differently associated with the aperiodic component depending on education: in older adults with high education, higher exponent predicted slower processing speed and less working memory capacity, while an opposite trend was found in those with low education. While further investigation is needed, this study shows the potential modulatory role of education in the relationship between the aperiodic component of the EEG power spectrum and aging cognition.

Peak alpha frequency and electroencephalographic microstates are correlated with aggression in schizophrenia

Large scale retrospective studies have shown an association between schizophrenia and risk of violence. Overall, this increase in risk is small and does not justify or support stigmatizing public perceptions or media depictions of people with schizophrenia. Nonetheless, in some situations, some symptoms of schizophrenia can increase the risk of violent behavior. Prediction of this behavior would allow high impact preventive interventions. However, to date the neurobiological correlates of violent behavior in schizophrenia are not well understood, precluding the development of prognostic biomarkers. We used electroencephalography to measure alpha activity and microstates from 31 patients with schizophrenia and 18 age matched controls. Participants also completed multiple assessments of current aggressive tendencies and their lifetime history of aggressive acts. We found that individual alpha peak frequency was negatively correlated with aggression scores in both patients and controls (largest Spearman's r = −0.45). Furthermore, this result could be replicated in data taken from a single frontal channel suggesting that this may be possible to obtain in routine clinical settings (largest Spearman's r = −0.40). We also found that transitions between microstates corresponding to auditory and visual networks were inversely correlated with aggression scores. Finally, we found that, within patients, aggression was correlated with the degree of randomness between microstate transitions. This suggests that aggression is related to inappropriate switching between large scale brain networks and subsequent failure to appropriately integrate complicated environmental and internal stimuli. By elucidating some of the electrophysiological correlates of aggression, these data facilitate the development of prognostic biomarkers.

Correlations between Visual Temporal Resolution and Individual Alpha Peak Frequency: Evidence that Internal and Measurement Noise Drive Null Findings.

The brain organizes the continuous flow of sensory input by parsing it into discrete events. In the case of two flashes separated by a brief ISI, for example, perception may be of a single flash or two distinct flashes, depending on the ISI but also on the speed of processing. A number of studies have reported evidence that participants with a higher EEG peak alpha frequency are able to detect the presence of two flashes separated by short intervals, whereas those with slower alpha report only one flash. Other studies have not found this correlation. We investigated potential factors that might mask the relationship between individual alpha frequency and visual perception. We recorded resting-state EEG from a large sample of participants (n = 50) and measured the temporal resolution of visual perception with the two-flash fusion task. We found that individual alpha frequency over posterior channels predicted the two-flash fusion threshold, in line with previous studies, but this correlation was significant only when taking into account the steepness of the psychophysical curve of the two-flash task. Participants with a relatively shallow psychophysical curve, likely reflecting high sensory and/or decision noise, failed to show this relationship. These findings replicate previous reports of a correlation between alpha frequency and visual temporal resolution, while also suggesting that an explanation of two-flash fusion performance that neglects the role of internal noise might be insufficient to account for all individual differences.

Alpha peak frequency affects visual performance beyond temporal resolution

Abstract Recent work suggests that the individual alpha peak frequency (IAPF) reflects the temporal resolution of visual processing: individuals with higher IAPF can segregate stimuli at shorter intervals compared to those with lower IAPF. However, this evidence mainly comes from studies focusing on short intervals, with stimulus onset asynchronies (SOA) rarely extending beyond a single alpha cycle (e.g., ~100 ms). Here, we investigated the relationship between IAPF and performance in visual backward masking (VBM), which allowed us to test the effects of IAPF for longer SOAs than an alpha cycle. A group of healthy controls (N = 79) and schizophrenia patients (N = 121), who generally exhibit lower IAPF, were tested in conditions with a Vernier shown alone, a Vernier followed by a mask at two SOAs (30 and 150 ms), or only a mask. Our results show that IAPF can predict VBM performance in all conditions with a Vernier. Furthermore, in both the control and schizophrenia groups, individuals with higher IAPF showed reduced masking effects, even when the SOA of 150 ms exceeded the alpha cycle. These findings challenge the notion that IAPF is exclusively related to temporal resolution and visual processing within a single alpha cycle. We discuss alternative mechanisms by which IAPF determines visual performance.

Resting EEG Periodic and Aperiodic Components Predict Cognitive Decline Over 10 Years.

Measures of intrinsic brain function at rest show promise as predictors of cognitive decline in humans, including EEG metrics such as individual α peak frequency (IAPF) and the aperiodic exponent, reflecting the strongest frequency of α oscillations and the relative balance of excitatory/inhibitory neural activity, respectively. Both IAPF and the aperiodic exponent decrease with age and have been associated with worse executive function and working memory. However, few studies have jointly examined their associations with cognitive function, and none have examined their association with longitudinal cognitive decline rather than cross-sectional impairment. In a preregistered secondary analysis of data from the longitudinal Midlife in the United States (MIDUS) study, we tested whether IAPF and aperiodic exponent measured at rest predict cognitive function (N = 235; age at EEG recording M = 55.10, SD = 10.71) over 10 years. The IAPF and the aperiodic exponent interacted to predict decline in overall cognitive ability, even after controlling for age, sex, education, and lag between data collection time points. Post hoc tests showed that "mismatched" IAPF and aperiodic exponents (e.g., higher exponent with lower IAPF) predicted greater cognitive decline compared to "matching" IAPF and aperiodic exponents (e.g., higher exponent with higher IAPF; lower IAPF with lower aperiodic exponent). These effects were largely driven by measures of executive function. Our findings provide the first evidence that IAPF and the aperiodic exponent are joint predictors of cognitive decline from midlife into old age and thus may offer a useful clinical tool for predicting cognitive risk in aging.

Limited usefulness of neurocognitive functioning indices as predictive markers for treatment response to methylphenidate or neurofeedback@home in children and adolescents with ADHD.

Earlier studies exploring the value of executive functioning (EF) indices for assessing treatment effectiveness and predicting treatment response in attention-deficit/hyperactivity disorder (ADHD) mainly focused on pharmacological treatment options and revealed rather heterogeneous results. Envisioning the long-term goal of personalized treatment selection and intervention planning, this study comparing methylphenidate treatment (MPH) and a home-based neurofeedback intervention (NF@Home) aimed to expand previous findings by assessing objective as well as subjectively reported EF indices and by analyzing their value as treatment and predictive markers. Children and adolescents (n = 146 in the per protocol sample) aged 7-13 years with a formal diagnosis of an inattentive or combined presentation of ADHD were examined. We explored the EF performance profile using the Conners Continuous Performance Task (CPT) and the BRIEF self-report questionnaire within our prospective, multicenter, randomized, reference drug-controlled NEWROFEED study with sites in five European countries (France, Spain, Switzerland, Germany, and Belgium). As primary outcome for treatment response, the clinician-rated ADHD Rating Scale-IV was used. Patients participating in this non-inferiority trial were randomized to either NF@home (34-40 sessions of TBR or SMR NF depending on the pre-assessed individual alpha peak frequency) or MPH treatment (ratio: 3:2). Within a mixed-effects model framework, analyses of change were calculated to explore the predictive value of neurocognitive indices for ADHD symptom-related treatment response. For a variety of neurocognitive indices, we found a significant pre-post change during treatment, mainly in the MPH group. However, the results of the current study reveal a rather limited prognostic value of neurocognitive indices for treatment response to either NF@Home or MPH treatment. Some significant effects emerged for parent-ratings only. Current findings indicate a potential value of self-report (BRIEF global score) and some objectively measured neurocognitive indices (CPT commission errors and hit reaction time variability) as treatment markers (of change) for MPH. However, we found a rather limited prognostic value with regard to predicting treatment response not (yet) allowing recommendation for clinical use. Baseline symptom severity was revealed as the most relevant predictor, replicating robust findings from previous studies.

Physical activity and verbal memory performance: Mediating effects of resting-state brain activity.

Verbal short-term and long-term memory are crucial neuropsychological functions involved in core cognitive abilities. They constitute vital components of subjective well-being and academic achievement. To date, there is limited research on the association between regular physical activity and memory abilities during young adulthood. The Individual Alpha Peak Frequency (IAPF) contributes to various cognitive abilities and also appears to be sensitive to physical activity. Consequently, the IAPF has the potential to underlie the association between physical activity and verbal memory. We examined the direct relation of physical activity and verbal memory, and the potential indirect relation via IAPF in young adults. Regular physical activity was assessed via accelerometry on seven consecutive days in 115 participants (N=115, 48% female) aged 18-35 years (M=24.1, SD=3.8). In addition, verbal memory performance was assessed using an immediate and delayed free-recall task. Brain activity during rest was recorded with EEG, and IAPF was extracted for mediation analyses. Path analysis revealed pronounced sex differences in the association between physical activity, IAPF, and verbal memory performance. Exclusively in female participants, higher vigorous physical activity levels were associated with better recall performance. In contrast, no association of physical activity and memory was found in male participants. However, being more physically active was related to a higher IAPF exclusively in male participants. Physical activity shows differential associations between IAPF and verbal memory in male and female participants. However, the lack of a mediating role of IAPF suggests that this neurophysiological marker cannot explain these specific associations in young adults.

Dreaming while awake: The beneficial effects of yoga Nidra on mental and physical recovery in two elite karate athletes

Yoga Nidra (YN) naturally stimulates a hypnagogic state wherein an individual is physiologically asleep yet maintains a certain awareness to follow a guide's instructions. The aim of this study was to investigate the effects of this aware sleep state on recovery-stress balance in two elite karate athletes adopting an idiosyncratic and multimodal approach. One male and one female athlete underwent a YN intervention. Before intervention, after intervention and three weeks later, recovery-stress balance specific scales, perceived stress, cognitive and somatic anxiety, subjective and objective sleep quality, and individual alpha peak frequency (iAPF) values were assessed. Perceived quality of recovery was continuously monitored for three months including the period of the investigation. Feelings and arousal levels before and after each YN session were also examined. Our results showed a YN general positive effect; however, the intervention had higher sport specific effects in the male compared to the female athlete. On the other hand, in the female athlete, YN seems to have effects both from an emotional and physical point of view. We also noted the intertwined relationship among interoception, perceived stress and YN effects. Also, findings suggest that iAPF modulation reflected improved recovery skills or a better control of stressful situations, while the acute effects on arousal levels were expression of anxiety or energy reduction. Overall, YN improved both the perceived quality of recovery and sleep quality, shedding light on the importance of YN for recovery-stress balance enhancement in the sport context.

Abnormalities in Occipital Cortical Sources of Resting‐State EEG Rhythms in Patients with Epileptiform Activity and Mild Cognitive Impairment due to Alzheimer’s Disease

AbstractBackgroundAlzheimer’s Disease (AD) patients present a higher risk of developing epilepsy compared to the age‐matched general population. Neurodegenerative cognitive disorders in general are closely linked with epilepsy and subclinical Epileptiform Electroencephalographic Activity (EEA). Furthermore, AD with Mild Cognitive Impairment (MCI) patients present abnormalities in posterior cortical sources of resting‐state eyes‐closed EEG rhythms at delta (< 4 Hz) and low‐frequency alpha (8‐10 Hz) rhythms. This retrospective study tested the hypothesis that ADMCI patients with EEA (ADMCI‐EEA) may be characterized by specific disease‐related abnormalities in delta and alpha rsEEG source activities compared with ADMCI patients without EEA (ADMCI‐noEEA) and noADMCI controls.MethodWe analysed data from an international database (www.pdwaves.org) comprising clinical, neuropsychological, rsEEG (25‐30 minutes), cerebrospinal fluid (CSF), and structural magnetic resonance imaging (sMRI) data in n = 42 ADMCI and n = 32 noADMCI patients without a diagnosis of epilepsy. The database also included clinical, neuropsychological, and rsEEG data of n = 38 matched cognitively unimpaired elderly (Nold) persons, used as additional controls in the present study. The rsEEG traces were reviewed by expert epileptologists blinded to the diagnostic status. EEA was detected in n = 8 ADMCI and n = 13 no‐ADMCI patients (Table 1). Individual alpha frequency peak (IAF) was used to determine the rsEEG delta, theta, and alpha bands. Regional rsEEG cortical sources were estimated using the eLORETA freeware.ResultCompared to the Nold and noADMCI‐noEEA groups, the noADMCI‐EEA group showed greater temporal rsEEG delta cortical source activity. Conversely, compared to the Nold and ADMCI‐noEEA groups, the ADMCI‐EEA group showed greater temporal and occipital rsEEG delta cortical source activity (Figure 1). Notably, CSF amyloid (but not sMRI‐based cortical atrophy) burden was greater in the ADMCI‐EEA than in ADMCI‐noEEA patients (Table 2).ConclusionThe abnormal temporal rsEEG delta cortical source activity in the ADMCI‐EEA and noADMCI‐EEA groups may reflect an unspecific susceptibility of the temporal lobe to slowing rsEEG activity for several neuropathological processes. Instead, the abnormal occipital rsEEG delta cortical source activity in the ADMCI‐EEA over the control groups may reflect a specific susceptibility of the occipital lobe to slowing rsEEG activity for AD‐related neuropathological processes in the cholinergic tract to the occipital cortex.

Relationship between default mode network and posterior resting‐state electroencephalographic delta rhythms in cognitively unimpaired seniors and patients with dementia due to Alzheimer’s

AbstractBackgroundAlzheimer’s disease dementia (ADD) is the most common neurodegenerative dementing disorder explaining about 60‐70% of 50 million patients worldwide (www.who.int). Some previous studies in ADD patients showed significant neurodegenerative processes as revealed by reduced gray matter volume in the cerebral cortex, including the default mode network (DMN), dorsal attention (DAN), and sensorimotor (SMN) cortical networks from structural magnetic resonance imaging (sMRI). Other studies in these patients reported the “slowing” of the resting‐state eyes‐closed electroencephalographic (rsEEG) rhythms reflecting vigilance dysfunctions. Here we tested the hypothesis of a significant relationship between these neurodegenerative and neurophysiological readouts, thus suggesting the sensitivity of rsEEG activity to intrinsic AD processes.MethodClinical, sMRI, and rsEEG rhythms in demographic‐ and age‐matched ADD (N = 45) and healthy cognitively unimpaired (Nold, N = 40) persons were available from an international archive (www.pdwaves.eu). Individual alpha frequency peak was used to determine the alpha frequency band on a personal basis. Fixed beta bands were considered. The eLORETA freeware estimated rsEEG sources in posterior (i.e., central, parietal, and occipital) cortical regions of interest. Freeware platforms served to estimate the normalized gray matter volume in the DMN, DAN, and SMN cortical networks from sMRI.ResultThe results (Fig. 1) showed: (1) lower DMN, DAN, and SMN volumes (maximum effects in the DMN), higher posterior rsEEG delta‐theta source activities, and lower rsEEG alpha source activities in the ADD than in the Nold group; (2) substantial inverse correlation between the DMN volume and the posterior rsEEG delta‐theta source activities in the ADD and Nold participants; and (3) a mediating effect of the posterior rsEEG delta‐theta source activities in the correlation between the DMN volume and the global cognitive status across all participants.ConclusionThese results suggest a prominent relationship between DMN atrophy and the posterior rsEEG delta‐theta rhythms across physiological and AD‐related aging. As such, they support the enrichment of the ATN model for an extension to “Physiology” (P) = A‐T‐P‐N, as the physiology of the oscillatory activity within large inter‐connected neuronal populations due to disruptive effects of AD‐related neuropathology can be additionally informative.

Association of the Brain-Derived Neurotrophic Factor Gene (BDNF) Val66Met Polymorphism with Individual Alpha Peak Frequency and Alpha Power in Adults

—A single nucleotide polymorphism in the brain-derived neurotrophic factor (BDNF) gene (Val66Met) functions to regulate activity-dependent secretion of (BDNF), which plays an important role in neuroprotection and synaptic plasticity. In several studies, the Met allele was associated with lower electroencephalogram (EEG) α-power values, calculated in the standard frequency range, in young subjects. In addition to α-power, one of the inherited EEG correlates of brain functioning is individual alpha peak frequency (IAPF). Although IAPF has a separate functional role, its association with BDNF Val66Met polymorphism has not been studied. IAPF is also used to determine the boundaries of individual frequency ranges, which, unlike the standard ones, are more consistent with functional rhythm characteristics. Using a sample of 192 subjects aged 18–78 years, the association between parietal-occipital IAPF and BDNF polymorphism, as well as the genotype differences in α-power calculated in standard (8–12 Hz) and individual frequency ranges (from (IAPF –2) to (IAPF +2) Hz) were examined. A decrease of IAPF in Val/Met compared to Val/Val was observed. For power calculated in the individual frequency range, genetic differences in both eyes-closed (Val/Met > homozygous genotypes) and eyes-open (Val-carriers > Met/Met) conditions were revealed. Analysis within the standard frequency range showed differences only in the eyes-open condition, which could be due to a shift of power indicators calculated in the α-rhythm functional range to the low frequency region among Val/Met carriers, which showed a decrease in IAPF. The results suggest that the inclusion of Val/Met in the pooled group of Met carriers in the analysis of genetic differences in brain activity may level out the differences between the Val/Val and Val/Met genotypes and show the advantage of using individual frequency bands in the analysis of BDNF Val66Met-associated EEG features.

Val66Met Polymorphism of Brain-Derived Neurotrophic Factor (BDNF) is Associated with Individual Alpha Peak Frequency and Alpha Power in Adults

Single-nucleotide polymorphism within the BDNF gene (Val66Met) influences activity-dependent secretion of the brain-derived neurotrophic factor (BDNF), which affects neuroprotection and synaptic plasticity. Several studies found associations between Met allele and lower power of the EEG α-rhythm determined in the standard frequency range in young adults. Along with the power, one of the highly heritable EEG correlates of brain functions is the individual α-peak frequency (IAPF). Although IAPF has independent functional significance, its association with the Val66Met BDNF polymorphism has not been studied. IAPF is also used to determine the boundaries of individual frequency ranges; in contrast to the standard ones, they reflect functional characteristics of rhythms to a greater extent. We explored in 192 subjects aged 18–78 years whether parieto-occipital IAPF is associated with BDNF polymorphism and tested genotypic differences in α-power calculated in standard (8−12 Hz) and individual (from (IAPF –2) to (IAPF +2) Hz) frequency ranges. IAPF was decreased in Val/Met in comparison to Val/Val. For individual frequency range, genetic differences were found in both eyes closed (Val/Met homozygous genotypes) and eyes open (Val-carriers Met/Met) condition. For standard frequency range – only in eyes open condition, which may be due to a shift of the α-functional range towards a region of low frequencies among Val/Met-carriers that showed a decrease in IAPF. The results indicate that the inclusion of Val/Met in the combined group of Met-carriers in the analysis of genetic differences in brain activity can eliminate the differences between Val/Val and Val/Met genotypes, as well as the advantage of using individual frequency bands in the analysis of BDNF-associated features of EEG.

Increased neurocardiological interplay after mindfulness meditation: a brain oscillation-based approach.

Brain oscillations facilitate interaction within the brain network and between the brain and heart activities, and the alpha wave, as a prominent brain oscillation, plays a major role in these coherent activities. We hypothesize that mindfully breathing can make the brain and heart activities more coherent in terms of increased connectivity between the electroencephalogram (EEG) and electrocardiogram (ECG) signals. Eleven participants (28-52 years) attended 8 weeks of Mindfulness Based Stress Reduction (MBSR) training. EEG and ECG data of two states of mindful breathing and rest, both eye-closed, were recorded before and after the training. EEGLAB was used to analyze the alpha band (8-12 Hz) power, alpha peak frequency (APF), peak power and coherence. FMRIB toolbox was used to extract the ECG data. Heart coherence (HC) and heartbeat evoked potential (HEP) were calculated for further correlation analysis. After 8 weeks of MBSR training, the correlation between APF and HC increased significantly in the middle frontal region and bilateral temporal regions. The correlation between alpha coherence and heart coherence had similar changes, while alpha peak power did not reflect such changes. In contrast, spectrum analysis alone did not show difference before and after MBSR training. The brain works in rhythmic oscillation, and this rhythmic connection becomes more coherent with cardiac activity after 8 weeks of MBSR training. Individual APF is relatively stable and its interplay with cardiac activity may be a more sensitive index than power spectrum by monitoring the brain-heart connection. This preliminary study has important implications for the neuroscientific measurement of meditative practice.

Genetic association of apolipoprotein E genotype with EEG alpha rhythm and resting‐state functional MRI connectivity in non‐demented adults during aging

AbstractBackgroundThe ε4 allele of the apolipoprotein E (APOE) genotype is a major genetic risk factor for Alzheimer’s disease (AD), but the mechanisms underlying its influence are not completely understood. The study was aimed at determining the possible effect of APOE genotype on spontaneous EEG alpha rhythm characteristics and on the resting‐state functional MRI (fMRI) connectivity (rsFC) in large brain networks in non‐demented adults during aging.MethodWe examined individual alpha peak frequency (IAPF), the EEG alpha sub‐bands power and the fMRI rsFC in 137 non‐demented volunteers, age range 26‐79 years, stratified by APOE genotype. APOE ε3/ε3 subgroup (APOE4‐) included 91 subjects, APOE ε4/ε3+ (APOE4+) subgroup – 46 subjects. The individuals underwent resting‐state fMRI of the brain, the CONN Matlab/SPM‐based toolbox was used to study connectivity in brain networks (Whitfield‐Gabrieli and Nieto‐Castanon, 2012). Informed written consent was obtained from all participants. All subjects underwent a neurological examination and cognitive screening.ResultThe presence of the APOE4+ genotype was associated with lower IAPF and lower relative power of the 11‐13Hz alpha sub‐bands. The age‐related alpha rhythm slowing was more pronounced in the APOE4+ than in the APOE4+ non‐carriers. The negative rsFC between the left hippocampus and the right posterior parietal cortex was reduced for the APOE4+ carriers compared to the APOE4‐ carriers. EEG IAFT showed a significant inverse correlation between rsFC of the left hippocampus and the right posterior parietal cortex.ConclusionAPOE4+ genotype is associated with marked age‐related alpha rhythm slowing and the dysfunction of the inhibitory large‐scale hippocampal networks. Inhibitory deficit of these networks function, interconnected with alpha rhythm slowing, may be related to learning and memory impairments and contribute to the subsequent AD development.This study was supported by Russian Science Foundation (Project No. 19‐75‐30039, genotyping)

Test-retest reliability of resting-state EEG in young and older adults.

The quantification of resting-state electroencephalography (EEG) is associated with a variety of measures. These include power estimates at different frequencies, microstate analysis, and frequency-resolved source power and connectivity analyses. Resting-state EEG metrics have been widely used to delineate the manifestation of cognition and to identify psychophysiological indicators of age-related cognitive decline. The reliability of the utilized metrics is a prerequisite for establishing robust brain-behavior relationships and clinically relevant indicators of cognitive decline. To date, however, test-retest reliability examination of measures derived from resting human EEG, comparing different resting-state measures between young and older participants, within the same adequately powered dataset, is lacking. The present registered report examined test-retest reliability in a sample of 95 young (age range: 20-35 years) and 93 older (age range: 60-80 years) participants. A good-to-excellent test-retest reliability was confirmed in both age groups for power estimates on both scalp and source levels as well as for the individual alpha peak power and frequency. Partial confirmation was observed for hypotheses stating good-to-excellent reliability of microstates measures and connectivity. Equal levels of reliability between the age groups were confirmed for scalp-level power estimates and partially so for source-level power and connectivity. In total, five out of the nine postulated hypotheses were empirically supported and confirmed good-to-excellent reliability of the most commonly reported resting-state EEG metrics.

Alterations in rhythmic and non‐rhythmic resting‐state EEG activity and their link to cognition in older age

While many structural and biochemical changes in the brain have previously been associated with older age, findings concerning functional properties of neuronal networks, as reflected in their electrophysiological signatures, remain rather controversial. These discrepancies might arise due to several reasons, including diverse factors determining general spectral slowing in the alpha frequency range as well as amplitude mixing between the rhythmic and non-rhythmic parameters. We used a large dataset (N = 1703, mean age 70) to comprehensively investigate age-related alterations in multiple EEG biomarkers taking into account rhythmic and non-rhythmic activity and their individual contributions to cognitive performance. While we found strong evidence for an individual alpha peak frequency (IAF) decline in older age, we did not observe a significant relationship between theta power and age while controlling for IAF. Not only did IAF decline with age, but it was also positively associated with interference resolution in a working memory task primarily in the right and left temporal lobes suggesting its functional role in information sampling. Critically, we did not detect a significant relationship between alpha power and age when controlling for the 1/f spectral slope, while the latter one showed age-related alterations. These findings thus suggest that the entanglement of IAF slowing and power in the theta frequency range, as well as 1/f slope and alpha power measures, might explain inconsistencies reported previously in the literature. Finally, despite the absence of age-related alterations, alpha power was negatively associated with the speed of processing in the right frontal lobe while 1/f slope showed no consistent relationship to cognitive performance. Our results thus demonstrate that multiple electrophysiological features, as well as their interplay, should be considered for the comprehensive assessment of association between age, neuronal activity, and cognitive performance.

One-year-later spontaneous EEG features predict visual exploratory human phenotypes

During visual exploration, eye movements are controlled by multiple stimulus- and goal-driven factors. We recently showed that the dynamics of eye movements –how/when the eye move– during natural scenes’ free viewing were similar across individuals and identified two viewing styles: static and dynamic, characterized respectively by longer or shorter fixations. Interestingly, these styles could be revealed at rest, in the absence of any visual stimulus. This result supports a role of intrinsic activity in eye movement dynamics. Here we hypothesize that these two viewing styles correspond to different spontaneous patterns of brain activity. One year after the behavioural experiments, static and dynamic viewers were called back to the lab to record high density EEG activity during eyes open and eyes closed. Static viewers show higher cortical inhibition, slower individual alpha frequency peak, and longer memory of alpha oscillations. The opposite holds for dynamic viewers. We conclude that some properties of spontaneous activity predict exploratory eye movement dynamics during free viewing.

Premenstrual syndrome is associated with an altered spontaneous electroencephalographic delta/beta power ratio across the menstrual cycle

Premenstrual syndrome is associated with altered spontaneous brain activity in the late luteal phase, but the fluctuation patterns of brain activity throughout the menstrual cycle have not been revealed. Furthermore, it is also unknown whether the altered spontaneous brain activity during the whole menstrual cycle is further associated with their habitual use of maladaptive emotion regulation strategies. Based on the two reasons, electroencephalogram data and cognitive emotion regulation questionnaire from 32 women with high premenstrual symptoms (HPMS) and 33 women with low premenstrual symptoms (LPMS) were measured in the late luteal and follicular phases. Delta power, theta power, beta power, and the slow/fast wave ratios (SW/FW, including theta/beta power ratio [TBR] and delta/beta power ratio [DBR]) were calculated using both fixed frequency bands and individually adjusted frequency bands (based on the individual alpha peak frequency). The results showed that for the frontal and central DBR, as assessed both with fixed and individualized frequency bands, there was no difference between the two phases of the LPMS group, whereas there was a difference between the two phases of the HPMS group with a higher DBR in the late luteal phase than in the follicular phase. Further correlation results revealed that for women with HPMS in the late luteal phase, the frontal and central DBR values, as assessed both with fixed and individualized frequency bands, were positively correlated with self-blame and rumination. Consequently, HPMS was characterized by a fluctuation across the menstrual cycle in the DBR, which was further associated with maladaptive emotion regulation.

Genetic association of apolipoprotein E genotype with EEG alpha rhythm slowing and functional brain network alterations during normal aging.

The ε4 allele of the apolipoprotein E (APOE4+) genotype is a major genetic risk factor for Alzheimer’s disease (AD), but the mechanisms underlying its influence remain incompletely understood. The study aimed to investigate the possible effect of the APOE genotype on spontaneous electroencephalogram (EEG) alpha characteristics, resting-state functional MRI (fMRI) connectivity (rsFC) in large brain networks and the interrelation of alpha rhythm and rsFC characteristics in non-demented adults during aging. We examined the EEG alpha subband’s relative power, individual alpha peak frequency (IAPF), and fMRI rsFC in non-demented volunteers (age range 26–79 years) stratified by the APOE genotype. The presence of the APOE4+ genotype was associated with lower IAPF and lower relative power of the 11–13 Hz alpha subbands. The age related decrease in EEG IAPF was more pronounced in the APOE4+ carriers than in the APOE4+ non-carriers (APOE4-). The APOE4+ carriers had a stronger fMRI positive rsFC of the interhemispheric regions of the frontoparietal, lateral visual and salience networks than the APOE4– individuals. In contrast, the negative rsFC in the network between the left hippocampus and the right posterior parietal cortex was reduced in the APOE4+ carriers compared to the non-carriers. Alpha rhythm slowing was associated with the dysfunction of hippocampal networks. Our results show that in adults without dementia APOE4+ genotype is associated with alpha rhythm slowing and that this slowing is age-dependent. Our data suggest predominant alterations of inhibitory processes in large-scale brain network of non-demented APOE4+ carriers. Moreover, dysfunction of large-scale hippocampal network can influence APOE-related alpha rhythm vulnerability.