Higher Alpha Power Research Articles

EEG Spectral Features Discriminate between Alzheimer's and Vascular Dementia.

Alzheimer’s disease (AD) and vascular dementia (VaD) present with similar clinical symptoms of cognitive decline, but the underlying pathophysiological mechanisms differ. To determine whether clinical electroencephalography (EEG) can provide information relevant to discriminate between these diagnoses, we used quantitative EEG analysis to compare the spectra between non-medicated patients with AD (n = 77) and VaD (n = 77) and healthy elderly normal controls (NC) (n = 77). We use curve-fitting with a combination of a power loss and Gaussian function to model the averaged resting-state spectra of each EEG channel extracting six parameters. We assessed the performance of our model and tested the extracted parameters for group differentiation. We performed regression analysis in a multivariate analysis of covariance with group, age, gender, and number of epochs as predictors and further explored the topographical group differences with pair-wise contrasts. Significant topographical differences between the groups were found in several of the extracted features. Both AD and VaD groups showed increased delta power when compared to NC, whereas the AD patients showed a decrease in alpha power for occipital and temporal regions when compared with NC. The VaD patients had higher alpha power than NC and AD. The AD and VaD groups showed slowing of the alpha rhythm. Variability of the alpha frequency was wider for both AD and VaD groups. There was a general decrease in beta power for both AD and VaD. The proposed model is useful to parameterize spectra, which allowed extracting relevant clinical EEG key features that move toward simple and interpretable diagnostic criteria.

Premovement high-alpha power is modulated by previous movement errors: Indirect evidence to endorse high-alpha power as a marker of resource allocation during motor programming.

Previous electroencephalographic studies have identified premovement high‐alpha power as a predictor of movement accuracy; less frontal‐central high‐alpha power is associated with accurate movements (e.g., holed golf putts), and could reflect more cognitive resources being allocated to response programming. The present experiment tested this interpretation. Ten expert and ten novice golfers completed 120 putts while high‐alpha power was recorded and analyzed as a function of whether the previous putt was holed (i.e., a correct response) or missed (i.e., an error). Existing evidence indicates that more resources are allocated to response programming following errors. We observed less premovement high‐alpha power following errors, especially in experts. Our findings provide indirect evidence that high‐alpha power is an inverse marker of the amount of resources allocated to motor response programming.

Electrophysiological Indices of Competition for Neural Resources in a Dual Working-Memory and Selective-Attention Task

Event Abstract Back to Event Electrophysiological Indices of Competition for Neural Resources in a Dual Working-Memory and Selective-Attention Task Dion Henare1, 2* and Paul Corballis1, 2 1 University of Auckland, School of Psychology, New Zealand 2 University of Auckland, Centre for Brain Research, New Zealand Visual selective attention performs an essential function in the human visual system, preferentially processing the most salient and relevant pieces of information in a scene. In this way, selective attention acts as a gate for high level, limited capacity processes like working memory. Evidence has also shown however that the contents of working memory can influence the performance of selective attention and this apparent interaction has led some to suggest that the two processes share the same limited neural resources. Previous studies have shown that increasing the load on an individual's working memory leads them to become more distractible in an attention task. In this experiment we recorded scalp EEG while participants perform a modified version of the localised attentional interference (LAI) paradigm under different levels of working memory load. The LAI paradigm allows us to show working-memory load effects on the amplitude of the attention-related lateralised components of the event-related brain potential (N2pc, Ptc, and SPCN), which have been related to target selection, distractor suppression, and working memory processes respectively. In addition, we have explored the EEG correlates of switching between the working-memory encoding task and the LAI task. We observe significant decreases in occipital alpha activity when participants initially switch to the LAI task following working-memory encoding, however this is only true for individuals with high baseline alpha power. This alpha decrease has been related to phasic arousal and alertness in previous task switching paradigms, and therefore its coincidence with behavioural differences in our task suggests that it may be an important factor to consider when studying the interaction of selective attention and working memory. Keywords: Attention, task-switching, working memory, Interaction, VEP, alpha modulation, lateralized ERP Conference: XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014. Presentation Type: Poster Topic: Attention Citation: Henare D and Corballis P (2015). Electrophysiological Indices of Competition for Neural Resources in a Dual Working-Memory and Selective-Attention Task. Conference Abstract: XII International Conference on Cognitive Neuroscience (ICON-XII). doi: 10.3389/conf.fnhum.2015.217.00181 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 19 Feb 2015; Published Online: 24 Apr 2015. * Correspondence: Mr. Dion Henare, University of Auckland, School of Psychology, Auckland, New Zealand, Dion.Henare@auckland.ac.nz Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Dion Henare Paul Corballis Google Dion Henare Paul Corballis Google Scholar Dion Henare Paul Corballis PubMed Dion Henare Paul Corballis Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Decreased delta sleep ratio and elevated alpha power predict vulnerability to depression during interferon-alpha treatment.

Although poor sleep accompanies depression, it is unknown which specific sleep abnormalities precede depression. This is similarly the case for depression developing during interferon-α (IFN-α) therapy. Because vulnerability becomes evident in those who slept poorly before IFN-α, we prospectively determined which specific aspect of sleep could predict subsequent depression. Two nights of polysomnography with quantitative electroencephalogram (EEG) were obtained in 24 adult, euthymic subjects--all subsequently treated with IFN-α for hepatitis C. Every 2 weeks, a Beck Depression Inventory-II (BDI-II) score was obtained, and the maximal increase in BDI-II from pre-treatment baseline--excluding the sleep question--was determined. The delta sleep ratio (DSR; an index of early-night restorative delta power) was inversely associated with BDI-II increases (p<0.01), as was elevated alpha power (8-12 Hz; p<0.001). Both delta (0.5-4 Hz) and alpha power exhibited high between-night correlations (r=0.83 and 0.92, respectively). In mixed-effect repeated-measure analyses, there was an interaction between alpha power and DSR (p<0.001)--subjects with low alpha power and elevated DSR were resilient to developing depression. Most other sleep parameters--including total sleep time and percentage of time in slow wave sleep--were not associated with subsequent changes in depression. Both high DSR and low alpha power may be specific indices of resilience. As most other aspects of sleep were not associated with resilience or vulnerability, sleep interventions to prevent depression may need to specifically target these specific sleep parameters.

Childhood EEG frontal alpha power as a predictor of adolescent antisocial behavior: A twin heritability study

High EEG frontal alpha power (FAP) is thought to represent a state of low arousal in the brain, which has been related in past research to antisocial behavior (ASB). We investigated a longitudinal sample of 900 twins in two assessments in late childhood and mid-adolescence to verify whether relationships exist between FAP and both aggressive and nonaggressive ASB. ASB was measured by the Child Behavioral Checklist, and FAP was calculated using connectivity analysis methods that used principal components analysis to derive power of the most dominant frontal activation. Significant positive predictive relationships emerged in males between childhood FAP and adolescent aggressive ASB using multilevel mixed modeling. No concurrent relationships were found. Using bivariate biometric twin modeling analysis, the relationship between childhood FAP and adolescent aggressive ASB in males was found to be entirely due to genetic factors, which were correlated r=0.22.

Investigating the efficacy of neurofeedback training for expediting expertise and excellence in sport

ObjectivesThis experiment examined whether electroencephalographic (EEG)-based neurofeedback could be used to train recreational golfers to regulate their brain activity, expedite skill acquisition, and promote robust performance under pressure. DesignWe adopted a mixed-multifactorial design, with group (neurofeedback, control) as a between-subjects factor, and pressure (low, high), session (pre-test, acquisition 1, acquisition 2, acquisition 3, post-test), block (putts within each training session), and epoch (cortical activity in the seconds around movement initiation) as within-subject factors. MethodsRecreational golfers received three hours of either true (to reduce frontal EEG high-alpha power, N = 12) or false (control, N = 12) neurofeedback training sandwiched between pre-test and post-test sessions during which we collected measures of cortical activity (EEG) and putting performance under both low and high pressure conditions. ResultsIndividuals in the neurofeedback group learned to reduce their frontal high-alpha power before striking putts. Despite causing this more “expert-like” pattern of cortical activity, neurofeedback training failed to selectively enhance performance, as both groups improved their putting performance similarly from the pre-test to the post-test. Finally, both groups performed robustly under pressure. ConclusionsPerformers can learn to regulate their brain activity using neurofeedback training. However, research identifying the cortical correlates of expertise is required to refine neurofeedback interventions if this training method is to expedite learning. Suggestions for future neurofeedback interventions are discussed.

Maintenance of relational information in working memory leads to suppression of the sensory cortex.

Working memory (WM) for sensory-based information about individual objects and their locations appears to involve interactions between lateral prefrontal and sensory cortexes. The mechanisms and representations for maintenance of more abstract, nonsensory information in WM are unknown, particularly whether such actively maintained information can become independent of the sensory information from which it was derived. Previous studies of WM for individual visual items found increased electroencephalogram (EEG) alpha (8-13 Hz) power over posterior electrode sites, which appears to correspond to the suppression of cortical areas that represent irrelevant sensory information. Here, we recorded EEG while participants performed a visual WM task that involved maintaining either concrete spatial coordinates or abstract relational information. Maintenance of relational information resulted in higher alpha power in posterior electrodes. Furthermore, lateralization of alpha power due to a covert shift of attention to one visual hemifield was marginally weaker during storage of relational information than during storage of concrete information. These results suggest that abstract relational information is maintained in WM differently from concrete, sensory representations and that during maintenance of abstract information, posterior sensory regions become task irrelevant and are thus suppressed.

Preparation for action: psychophysiological activity preceding a motor skill as a function of expertise, performance outcome, and psychological pressure.

Knowledge of the psychophysiological responses that characterize optimal motor performance is required to inform biofeedback interventions. This experiment compared cortical, cardiac, muscular, and kinematic activity in 10 experts and 10 novices as they performed golf putts in low- and high-pressure conditions. Results revealed that in the final seconds preceding movement, experts displayed a greater reduction in heart rate and EEG theta, high-alpha, and beta power, when compared to novices. EEG high-alpha power also predicted success, with participants producing less high-alpha power in the seconds preceding putts that were holed compared to those that were missed. Increased pressure had little impact on psychophysiological activity. It was concluded that greater reductions in EEG high-alpha power during preparation for action reflect more resources being devoted to response programming, and could underlie successful accuracy-based performance.

Alpha power increases in right parietal cortex reflects focused internal attention

This study investigated the functional significance of EEG alpha power increases, a finding that is consistently observed in various memory tasks and specifically during divergent thinking. It was previously shown that alpha power is increased when tasks are performed in mind—e.g., when bottom-up processing is prevented. This study aimed to examine the effect of task-immanent differences in bottom-up processing demands by comparing two divergent thinking tasks, one intrinsically relying on bottom-up processing (sensory-intake task) and one that is not (sensory-independence task). In both tasks, stimuli were masked in half of the trials to establish conditions of higher and lower internal processing demands. In line with the hypotheses, internal processing affected performance and led to increases in alpha power only in the sensory-intake task, whereas the sensory-independence task showed high levels of task-related alpha power in both conditions. Interestingly, conditions involving focused internal attention showed a clear lateralization with higher alpha power in parietal regions of the right hemisphere. Considering evidence from fMRI studies, right-parietal alpha power increases may correspond to a deactivation of the right temporoparietal junction, reflecting an inhibition of the ventral attention network. Inhibition of this region is thought to prevent reorienting to irrelevant stimulation during goal-driven, top-down behavior, which may serve the executive function of task shielding during demanding cognitive tasks such as idea generation and mental imagery.

The time-course of alpha neurofeedback training effects in healthy participants

The time-course of alpha neurofeedback training (NFT) was investigated in 18 healthy participants who received 15 sessions of training (eyes open), each consisting of three training periods (data are from Van Boxtel et al., 2012). Here we report on the within- and between-session training effects using multilevel analyses. Over sessions, total alpha power (8–12Hz) increased up to the tenth session, after which low alpha power (8–10Hz) remained at the same level, while high alpha power (10–12Hz) decreased. Within each training session, total alpha power increased from the first to the second period, and then decreased again. This decrease, however, was caused by a decrease in high alpha power only; low alpha power remained up to the end of training. These effects are discussed in terms of attention and motivation, and suggest different trainability for low and high alpha power.

The moderating influence of nicotine and smoking on resting-state mood and EEG changes in remitted depressed patients during tryptophan depletion

Comorbidity between depression and tobacco use may reflect self-medication of serotonergically mediated mood dysregulation, which has been associated with aberrant cortical activation and hemispheric asymmetry in patients with major depressive disorders (MDD). This randomized, double-blind study in 28 remitted MDD patients examined the moderating effects of acute nicotine and smoker vs. nonsmoker status on mood and EEG changes accompanying transient reductions in serotonin induced by acute tryptophan depletion (ATD). In smokers, who exhibited greater posterior high alpha power and increased left frontal low alpha power (signs of deactivation) compared to nonsmokers, ATD increased self-ratings of depressed mood and elevated left frontal and right parietal high alpha power (i.e. further cortical deactivation). Smokers were not affected by nicotine administration. In nonsmokers, ATD did not influence depression ratings, but it reduced vigor ratings and increased frontal and posterior theta power; both of which were blocked by acute nicotine. These findings indicate a role for nicotinic receptors in disordered mood.

The influence of social evaluation on cerebral cortical activity and motor performance: A study of “Real-Life” competition

Motor performance in a social evaluative environment was examined in participants (N=19) who completed a pistol shooting task under both performance-alone (PA) and competitive (C) conditions. Electroencephalographic (EEG), autonomic, and psychoendocrine activity were recorded in addition to kinematic measures of the aiming behavior. State anxiety, heart rate, and cortisol were modestly elevated during C and accompanied by relative desynchrony of high-alpha power, increased cortico-cortical communication between motor and non-motor regions, and degradation of the fluency of aiming trajectory, but maintenance of performance outcome (i.e., score). The findings reveal that performance in a complex social-evaluative environment characterized by competition results in elevated cortical activity beyond that essentially required for motor performance that translated as less efficient motor behavior.

Spontaneous EEG alpha oscillation interacts with positive and negative BOLD responses in the visual–auditory cortices and default-mode network

The human brain is continually, dynamically active and spontaneous fluctuations in this activity play a functional role in affecting both behavioural and neuronal responses. However, the mechanisms through which this occurs remain poorly understood. Simultaneous EEG-fMRI is a promising technique to study how spontaneous activity modulates the brain's response to stimulation, as temporal indices of ongoing cortical excitability can be integrated with spatially localised evoked responses. Here we demonstrate an interaction between the ongoing power of the electrophysiological alpha oscillation and the magnitude of both positive (PBR) and negative (NBR) fMRI responses to two contrasts of visual checkerboard reversal. Furthermore, the amplitude of pre-stimulus EEG alpha-power significantly modulated the amplitude and shape of subsequent PBR and NBR to the visual stimulus. A nonlinear reduction of visual PBR and an enhancement of auditory NBR and default-mode network NBR were observed in trials preceded by high alpha-power. These modulated areas formed a functionally connected network during a separate resting-state recording. Our findings suggest that the "baseline" state of the brain exhibits considerable trial-to-trial variability which arises from fluctuations in the balance of cortical inhibition/excitation that are represented by respective increases/decreases in the power of the EEG alpha oscillation. The consequence of this spontaneous electrophysiological variability is modulated amplitudes of both PBR and NBR to stimulation. Fluctuations in alpha-power may subserve a functional relationship in the visual-auditory network, acting as mediator for both short and long-range cortical inhibition, the strength of which is represented in part by NBR.

The Effect of Foster Care on Social Skills

Almas AN, Degnan KA, Radulescu A, et al. Effects of early intervention and the moderating effect of brain activity on institutionalized children’s social skills at age 8. PNAS. 2012; 10(Suppl 2): 17228-17231; doi: 10.1073/pnas.1121256109Investigators from multiple institutions sought to understand the effect of early foster care placement on the social skills of previously institutionalized children when they reached middle childhood. This study was part of the Bucharest Early Intervention Project (BEIP) that began in 2001. BEIP is a randomized controlled trial of foster care as an intervention for children abandoned at birth and placed in 1 of 6 institutions for young children in Bucharest, Romania. At the outset of the BEIP, 136 institutionalized children were randomized to either foster care or usual care in the institution in which they currently resided. Children who were randomized to foster care were initially placed at ages 7 to 35 months. A control group of non-institutionalized children from the Bucharest community were also enrolled and were matched on age and gender to children in the intervention groups.For the current study, children had their attachment security to a primary caregiver (foster mother or favorite caregiver in the institution) assessed by the preschool version of the Strange Situation Procedure when they were 42 months old. When participants were 8 years old, brain electrical activity (EEG) was obtained; EEG power in the alpha band (7-12 Hz) was computed, since alpha activity is associated with attention and processing of sensory information and high alpha power reflects cortical maturity.1 The primary outcome was social skills which were measured by administering the Social Skills Rating System (SSRS) to their teachers when the children were 8 years old. Social skills of children in each of the 3 groups were compared, and the effects of age at foster care placement, EEG alpha power, and attachment security on this outcome were assessed.In the present study, there were 44 children in the usual care group, 52 in the foster care group, and 97 in the control group. Only 12 children in the usual care group were still living in an institution at age 8 years. Overall, children in the control group were rated significantly higher on social skills than children in the foster care and usual care groups. However, children placed in foster care before 20 months of age were rated no differently on social skills than control children and were rated significantly higher than usual care children. High EEG power in the alpha band among usual care and foster care children was significantly associated with better attachment security and social skills. There was no significant relationship between attachment security and social skills in usual care and foster care children who had low EEG power in the alpha band.The authors conclude that forming secure foster care relationships positively influences social skills of children who have experienced severe social deprivation from early institutionalization, and that alpha electrical activity appears important in the relationship between attachment and social skills.Middle childhood is a period of increasing interest to both foster and adoptive parents because poor social skills at this critical time in a child’s life can lead to rejection and exclusion by their peers during the transition to adolescence.2 Wiik et al recently reported that postinstitutionalized children have a greater risk of attention-deficit hyperactivity disorder symptoms and emotional or internalizing behavioral disorders than children in foster care/minimal institutionalization and control children (see AAP Grand Rounds, June 2011;25[6]:623). Erol et al found that institutionalized adolescents with few friends and poor relationships have more internalizing and externalizing problem behaviors, which can persist into and complicate their adulthood.4In the current study the BEIP provided researchers a unique opportunity to evaluate how variations in attachment relationships can influence the negative impact of early institutionalization. The investigators have proffered evidence that foster care has the expected positive influence on the social development of children who have experienced deprivation, as long as the intervention occurs early enough in life. However, the results also demonstrate that future research must consider other factors, such as brain development, which can dramatically affect the attachment-social skills relationship.Life is full of limited time offers. For institutionalized children, this study now helps pinpoint the deadline (ie, 20 months of age) after which a critical intervention may no longer change the future bleak outcome and direction of a child’s life. And, like the hidden catches in many of these limited time offers, there is no guarantee that a good intervention will result in the desired outcome.

Adverse Listening Conditions and Memory Load Drive a Common Alpha Oscillatory Network

How does acoustic degradation affect the neural mechanisms of working memory? Enhanced alpha oscillations (8-13 Hz) during retention of items in working memory are often interpreted to reflect increased demands on storage and inhibition. We hypothesized that auditory signal degradation poses an additional challenge to human listeners partly because it draws on the same neural mechanisms. In an adapted Sternberg paradigm, auditory memory load and acoustic degradation were parametrically varied and the magnetoencephalographic response was analyzed in the time-frequency domain. Notably, during the stimulus-free delay interval, alpha power monotonically increased at central-parietal sensors as functions of memory load (higher alpha power with more memory load) and of acoustic degradation (also higher alpha power with more severe acoustic degradation). This alpha effect was superadditive when highest load was combined with most severe degradation. Moreover, alpha oscillatory dynamics during stimulus-free delay were predictive of response times to the probe item. Source localization of alpha power during stimulus-free delay indicated that alpha generators in right parietal, cingulate, supramarginal, and superior temporal cortex were sensitive to combined memory load and acoustic degradation. In summary, both challenges of memory load and acoustic degradation increase activity in a common alpha-frequency network. The results set the stage for future studies on how chronic or acute degradations of sensory input affect mechanisms of executive control.

Effects of ongoing brain oscillations on psychometric functions

Extract single trials' power in a specific TF window. (This will be repeated for all TF windows of interest) For each TF window, sort trials in 3 bins: • low-alpha power • mid-alpha power • hi-alpha power For each TF window, fit performance with a Weibull function. • low-alpha power: Threshold (α) and Slope (β) • mid-alpha power: Threshold (α) and Slope (β) • high-alpha power: Threshold (α) and Slope (β) Lo Mi Hi Pe rf or m an ce

Neural expression of nicotine's antidepressant properties during tryptophan depletion: An EEG study in healthy volunteers at risk for depression

Nicotine amelioration of serotonergically mediated mood dysregulation may contribute to the comorbidity between cigarette smoking and depression, a disorder which is associated with aberrant activation and hemispheric asymmetry in frontal and posterior cortical regions. This randomized, double-blind study in 20 healthy volunteers with a positive family history of depression examined the effects of transdermal nicotine on mood and EEG changes accompanying transient reductions in serotonin induced by acute tryptophan depletion (ATD). Increased self-ratings of depressed mood and elevation in left frontal high alpha power (decreased activation) were evidenced with ATD (vs. balanced mixture) in participants treated with the placebo but not the nicotine treated group. Nicotine alone increased vigor and posterior high alpha bilaterally, and during ATD it prevented the reduction in left frontal high alpha that was evident in the placebo patch group.These findings indicate that in depression prone individuals, nicotine acts to stabilize the mood lowering and associated frontal functional asymmetry elicited by an acute decrease in brain serotonin.

Modulations of ongoing alpha oscillations predict successful short-term visual memory encoding

Alpha-frequency band oscillations have been shown to be one of the most prominent aspects of neuronal ongoing oscillatory activity, as reflected by electroencephalography (EEG) recordings. First thought to reflect an idling state, a recent framework indicates that alpha power reflects cortical inhibition. In the present study, the role of oscillations in the upper alpha-band (12 Hz) was investigated during a change-detection test of short-term visual memory. If alpha oscillations arise from a purely inhibitory process, higher alpha power before sample stimulus presentation would be expected to correlate with poorer performance. Instead, participants with faster reaction-times showed stronger alpha power before the sample stimulus in frontal and posterior regions. Additionally, faster participants showed stronger alpha desynchronization after the stimulus in a group of right frontal and left posterior electrodes. The same pattern of electrodes showed stronger alpha with higher working-memory load, so that when more items were processed, alpha power desynchronized faster after the stimulus. During memory maintenance, alpha power was greater when more items were held in memory, likely due to a faster resynchronization. These data are consistent with the hypothesis that the level of suppression of alpha power by stimulus presentation is an important factor for successfully encoding visual stimuli. The data are also consistent with a role for alpha as actively participating in attentional processes.

EEG alpha rhythms and transient chromatic and achromatic pattern visual evoked potentials in children and adults

Transient chromatic pattern visual evoked potentials (VEPs) have been found to be less repeatable in morphology in children than in adults at low to moderate chromatic contrasts. The purpose of this study is to investigate whether low repeatability of VEP components can be associated with high alpha power, in a comparison of alpha activity in children and adults. Transient chromatic contrast and achromatic resolution VEPs were recorded in children (n=14, mean 9.6years) and adults (n=12, mean 21.8years) with normal vision and assessed for repeatability. Isoluminant chromatic (magenta-cyan) and luminance-modulated achromatic grating stimuli were presented at and above psychophysical threshold levels, in pattern onset-offset at 2Hz temporal frequency. EEGs (eyes closed and open) were recorded as single sweeps (1s long) over three 30s periods while facing a uniform computer display. An index of VEP detectability by observation was developed based on VEP component repeatability. The index was examined for correlations with alpha-wave parameters. Alpha power was calculated as the sum of the powers of 8-13Hz frequencies of the EEG sweeps (using the discrete Fourier transform). Alpha power variability was calculated using the standard deviation of the powers of each sweep in a 30s time period. The children had significantly higher alpha powers than the adults for both the eyes-open and eyes-closed conditions. Alpha power variability was significantly higher for the eyes-open condition only. There was no relationship between alpha power parameters and index of VEP detectability by observation for both the chromatic and achromatic grating stimuli. Poor repeatability of transient pattern VEPs is not associated with high alpha power or its variability in EEG measurements in older children or young adults at Oz.

Timing of intervention affects brain electrical activity in children exposed to severe psychosocial neglect.

BackgroundEarly psychosocial deprivation has profound effects on brain activity in the young child. Previous reports have shown increased power in slow frequencies of the electroencephalogram (EEG), primarily in the theta band, and decreased power in higher alpha and beta band frequencies in infants and children who have experienced institutional care.Methodology/Principal FindingsWe assessed the consequences of removing infants from institutions and placing them into a foster care intervention on brain electrical activity when children were 8 years of age. We found the intervention was successful for increasing high frequency EEG alpha power, with effects being most pronounced for children placed into foster care before 24 months of age.Conclusions/SignificanceThe dependence on age of placement for the effects observed on high frequency EEG alpha power suggests a sensitive period after which brain activity in the face of severe psychosocial deprivation is less amenable to recovery.