EEG Alpha Power Research Articles

INFLUENCE OF ALPHAEEG/EMG BIOFEEDBACK AND SELF-REGULATION PSYCHO TECHNIQUES ON THE HEART RATE VARIABILITY INDICES

With the purpose to study the impact of the upper frequency alpha EEG power increasing neurofeedback training (ANFT) on the cognitive performance, EEG alpha-activity and heart rate variability (HRV) 27 healthy men aged 18–34 years in pre, post and follow up one month 10 sessions ANFT time were investigated. The AFNT enhanced the fluency in cognitive performance, alpha frequency and power in upper frequency range and HRV only in participants with low baseline alpha frequency. While mock AFNT did change neither cognitive performance, nor alpha-activity, nor HRV indices. ANT reduces activation in cognitive load, and this effect persists for a month.

Correlated slow fluctuations in respiration, EEG, and BOLD fMRI

Low-frequency temporal fluctuations of physiological signals (<0.1 Hz), such as the respiration and cardiac pulse rate, occur naturally during rest and have been shown to be correlated with blood-oxygenation-level-dependent (BOLD) signal fluctuation. Such physiological signal modulations have been considered as sources of noise and their effects on BOLD signal are commonly removed in functional magnetic resonance imaging (fMRI) studies. However, possible neural correlates of the physiological fluctuations have not been considered nor examined in detail. In the present study we investigated this possibility by simultaneously acquiring electroencephalogram (EEG) with BOLD fMRI data, respiratory and cardiac waveforms in healthy human subjects at eyes-closed and eyes-open resting. We quantified the concurrent changes of the EEG power in the alpha frequency band, the respiration volume, and the cardiac pulse rate, then assessed the temporal correlations between alpha EEG power and physiological signal fluctuations. In addition, time-shifted time courses of alpha EEG power or physiological data were included as regressors to examine their correlations with the whole-brain BOLD fMRI signals. We observed a significant correlation between alpha EEG global field power and respiration, particularly at eyes-closed resting condition. Similar spatial patterns were observed between the correlation maps of BOLD with alpha EEG power and respiration, with negative correlations coinciding in the visual cortex, superior/middle temporal gyrus, inferior frontal gyrus, and inferior parietal lobule and positive correlations in the thalamus and caudate. Regressing out the physiological variations in the BOLD signal resulted in reduced correlation between BOLD and alpha EEG power. These results suggest a mutual link of neuronal origin between alpha EEG power, respiration, and BOLD signals.

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.

Neural mass modeling of power-line magnetic fields effects on brain activity

Neural mass models are an appropriate framework to study brain activity, combining a high degree of biological realism while being mathematically tractable. These models have been used, with a certain success, to simulate brain electric (electroencephalography, EEG) and metabolic (functional magnetic resonance imaging, fMRI) activity. However, concrete applications of neural mass models have remained limited to date. Motivated by experimental results obtained in humans, we propose in this paper a neural mass model designed to study the interaction between power-line magnetic fields (MFs) (60 Hz in North America) and brain activity. The model includes pyramidal cells; dendrite-projecting, slow GABAergic neurons; soma-projecting, fast GABAergic neurons; and glutamatergic interneurons. A simple phenomenological model of interaction between the induced electric field and neuron membranes is also considered, along with a model of post-synaptic calcium concentration and associated changes in synaptic weights Simulated EEG signals are produced in a simple protocol, both in the absence and presence of a 60 Hz MF. These results are discussed based on results obtained previously in humans. Notably, results highlight that (1) EEG alpha (8–12 Hz) power can be modulated by weak membrane depolarizations induced by the exposure; (2) the level of input noise has a significant impact on EEG power modulation; and (3) the threshold value in MF flux density resulting in a significant effect on the EEG depends on the type of neuronal populations modulated by the MF exposure. Results obtained from the model shed new light on the effects of power-line MFs on brain activity, and will provide guidance in future human experiments. This may represent a valuable contribution to international regulation agencies setting guidelines on MF values to which the general public and workers can be exposed.

The Effect of Alpha Rhythm Sleep on EEG Activity and Individuals’ Attention

[Purpose] This study examined whether the alpha rhythm sleep alters the EEG activity and response time in the attention and concentration tasks. [Subjects and Methods] The participants were 30 healthy university students, who were randomly and equally divided into two groups, the experimental and control groups. They were treated using the Happy-sleep device or a sham device, respectively. All participants had a one-week training period. Before and after training sessions, a behavioral task test was performed and EEG alpha waves were measured to confirm the effectiveness of training on cognitive function. [Results] In terms of the behavioral task test, reaction time (RT) variations in the experimental group were significantly larger than in the control group for the attention item. Changes in the EEG alpha power in the experimental group were also significantly larger than those of the control group. [Conclusions] These findings suggest that sleep induced using the Happy-sleep device modestly enhances the ability to pay attention and focus during academic learning.

Dynamic correlations between heart and brain rhythm during Autogenic meditation.

This study is aimed to determine significant physiological parameters of brain and heart under meditative state, both in each activities and their dynamic correlations. Electrophysiological changes in response to meditation were explored in 12 healthy volunteers who completed 8 weeks of a basic training course in autogenic meditation. Heart coherence, representing the degree of ordering in oscillation of heart rhythm intervals, increased significantly during meditation. Relative EEG alpha power and alpha lagged coherence also increased. A significant slowing of parietal peak alpha frequency was observed. Parietal peak alpha power increased with increasing heart coherence during meditation, but no such relationship was observed during baseline. Average alpha lagged coherence also increased with increasing heart coherence during meditation, but weak opposite relationship was observed at baseline. Relative alpha power increased with increasing heart coherence during both meditation and baseline periods. Heart coherence can be a cardiac marker for the meditative state and also may be a general marker for the meditative state since heart coherence is strongly correlated with EEG alpha activities. It is expected that increasing heart coherence and the accompanying EEG alpha activations, heart brain synchronicity, would help recover physiological synchrony following a period of homeostatic depletion.

Влияние тренинга произвольного увеличения альфа-мощности ЭЭГ на вариабельность сердечного ритма

In order to study the effect of the alpha EEG power increasing training at heart rate variability (HRV) as the index of the autonomic regulation of cognitive functions there were follow tasks: (1) to figure out the impact of biofeedback in the voluntary increasing the power in the individual high-frequency alpha-band effect on heart rate variability and related characteristics of cognitive and emotional spheres, (2) to determine the nature of the relationship between alpha activity indices and heart rate variability, depending on the alpha-frequency EEG pattern at rest (3) to examine how the individual alpha frequency EEG pattern is reflected in changes HRV as a result of biofeedback training. Psychometric indicators of cognitive performance, the characteristics of the alpha-EEG activity and heart rate variability (HRV) as LF/HF and pNN50 were recorded in 27 healthy men aged 18-34 years, before, during, and after 10 sessions of training of voluntary increase in alpha power in the individual high-frequency alpha band with eyes closed. To determine the biofeedback effect on the alpha power increasing training, data subjects are compared in 2 groups: experimental (14) with the real and the control group (13 people)--with mock biofeedback. The follow up effect of trainings was studied through month over the 10 training sessions. Results showed that alpha biofeedback training enhanced the fluency and accuracy in cognitive performance, decreased anxiety and frontal EMG, increased resting frequency, width and power in individual upper alpha range only in participants with low baseline alpha frequency. While mock biofeedback increased resting alpha power only in participants with high baseline resting alpha frequency and did change neither cognitive performance, nor HRV indices. Biofeedback training eliminated the alpha power decrease in response to arithmetic task in both with high and low alpha frequency participants and this effect was followed up over the month. Mock biofeedback training has no such effect. The positive correlation between the alpha-peak frequency and pNN50 in patients with initially low, but negative--those with high baseline alpha frequency explains the multidirectional biofeedback effects on HRV in low and high alpha frequency subjects. The individual alpha-frequency EEG pattern determines the effectiveness of the alpha EEG biofeedback training in changing heart rate variability, which provides a basis for predicting the results and develop individual approaches to the biofeedback technology implementation that can be used in clinical practice for treatment and rehabilitation of psychosomatic syndromes and in educational training.

Coupling between Intrinsic Prefrontal HbO2 and Central EEG Beta Power Oscillations in the Resting Brain

There is increasing interest in the intrinsic activity in the resting brain, especially that of ultraslow and slow oscillations. Using near-infrared spectroscopy (NIRS), electroencephalography (EEG), blood pressure (BP), respiration and heart rate recordings during 5 minutes of rest, combined with cross spectral and sliding cross correlation calculations, we identified a short-lasting coupling (duration s) between prefrontal oxyhemoglobin (HbO2) in the frequency band between 0.07 and 0.13 Hz and central EEG alpha and/or beta power oscillations in 8 of the 9 subjects investigated. The HbO2 peaks preceded the EEG band power peaks by 3.7 s in 6 subjects, with moderate or no coupling between BP and HbO2 oscillations. HbO2 and EEG band power oscillations were approximately in phase with BP oscillations in the 2 subjects with an extremely high coupling (squared coherence ) between BP and HbO2 oscillation. No coupling was identified in one subject. These results indicate that slow precentral (de)oxyhemoglobin concentration oscillations during awake rest can be temporarily coupled with EEG fluctuations in sensorimotor areas and modulate the excitability level in the brains’ motor areas, respectively. Therefore, this provides support for the idea that resting state networks fluctuate with frequencies of between 0.01 and 0.1 Hz (Mantini et.al. PNAS 2007).

Regional EEG alpha power, coherence, and behavioral symptomatology in autism spectrum disorder

ObjectiveAlthough distinct patterns of resting brain electrical activity (EEG) and functional connectivity are believed to distinguish individuals with autism spectrum disorders (ASD) from their unimpaired peers, researchers have only recently begun to link patterns of brain activity and connectivity to behavior in ASD. MethodWe examined regional eyes-closed and eyes-open EEG alpha power and coherence at rest in relation to self-reported perceptual and social behavior in 15 adults diagnosed with ASD and a matched comparison group of 16 unimpaired adults. ResultsThe groups did not differ on eyes-closed EEG alpha power or coherence, but adults with ASD showed less alpha suppression for the eyes-open condition than did controls. In the ASD group, preferential attention to detail (perceptual domain) was associated with lower levels of alpha activity and reduced coherence in posterior regions. No relations between social interaction difficulties (social domain) and alpha measures were found for either group alone. ConclusionsThese relations suggest that the processing of perceptual details may be carried out by relatively less synchronized neuronal units in adults with ASD, and may be relatively automatic. SignificanceFindings are discussed in relation to recent models of narrow minicolumnar brain structure and reduced functional neural connectivity in ASD.

Tackling creativity at its roots: Evidence for different patterns of EEG alpha activity related to convergent and divergent modes of task processing

The distinction between convergent and divergent cognitive processes given by Guilford (1956) had a strong influence on the empirical research on creative thinking. Neuroscientific studies typically find higher event-related synchronization in the EEG alpha rhythm for individuals engaged in creative ideation tasks compared to intelligence-related tasks. This study examined, whether these neurophysiological effects can also be found when both cognitive processing modes (convergent vs. divergent) are assessed by means of the same task employing a simple variation of instruction. A sample of 55 participants performed the alternate uses task as well as a more basic word association task while EEG was recorded. On a trial-by-trial basis, participants were either instructed to find a most common solution (convergent condition) or a most uncommon solution (divergent condition). The answers given in the divergent condition were in both tasks significantly more original than those in the convergent condition. Moreover, divergent processing was found to involve higher task-related EEG alpha power than convergent processing in both the alternate uses task and the word association task. EEG alpha synchronization can hence explicitly be associated with divergent cognitive processing rather than with general task characteristics of creative ideation tasks. Further results point to a differential involvement of frontal and parietal cortical areas by individuals of lower versus higher trait creativity.

Residual brain dysfunction observed one year post-mild traumatic brain injury: Combined EEG and balance study

ObjectivesThere is still considerable debate and controversy about whether EEG can be used as a robust clinical tool for assessment of mild traumatic brain injury (MTBI). Nonhomogeneous subject populations, inaccurate assessment of severity of brain injury, time since injury when EEG testing was performed, the lack of EEG research conducted serially and in conjunction with other behavioral measures as injury evolves over time may contribute to the existing controversies. In this study, we implemented a concussion assessment protocol combining a series of EEG and balance measures throughout one year post-injury to document the efficacy of EEG and balance measures as relate to differential recovery of patients suffering from MTBI. MethodsThree hundred and eighty subjects at risk for MTBI were initially recruited for baseline testing. Forty nine from this initial subjects pool subsequently suffered a single episode of concussive blow and were tested on day 7, 15, 30days, 6months and 12months post-injury. EEGs were recorded while sitting, standing on the force plate and then on a foam base of support with eyes open/closed conditions. EEG alpha power (8–12Hz) and its percent suppression from sitting to standing postures were computed. The center of pressure (COP) measures were obtained from the force platform and analyzed for eyes open and eyes closed conditions. ResultsPercent alpha power suppression from sitting to standing postural conditions significantly increased in MTBI subjects shortly after the injury (p<0.01). Percent alpha power suppression significantly correlated with increased area of COP during standing posture with eye closed (r2=0.53, p<0.01). The magnitude of alpha power suppression predicted the rate of recovery of this measure in sub-acute and chronic phases of injury (r2=0.609, p<0.01). Finally, 85% of MTBI subjects who showed more than 20% of alpha power suppression in the acute phase of injury did not return to pre-injury status up to 12months post-injury. ConclusionsThe efficacy of serially implemented EEG measures in conjunction with balance assessment over the course of MTBI evolution to document residual cerebral dysfunction was demonstrated. Specifically, alteration of EEG alpha power dynamics in conjunction with balance data in the acute phase of injury with respect to baseline measures may predict the rate of recovery from a single concussive blow. SignificanceNeurophysiological measures are excellent tools to assess the status and prognosis of patients with MTBI.

Is “conflict adaptation” driven by conflict? Behavioral and EEG evidence for the underappreciated role of congruent trials

Theories of cognitive control argue that response conflict in speeded performance tasks leads to adaptive changes, such that irrelevant information is better ignored on subsequent trials. This study tested whether trial-by-trial changes are driven primarily by conflict on incongruent trials or instead by congruent trials, in which irrelevant and relevant stimulus dimensions match. In a Stroop task including congruent, incongruent, and neutral trials, interference was greater following congruent compared to incongruent and neutral trials, which did not differ. During the intertrial interval, EEG alpha power, an inverse measure of cerebral activation, was significantly lower following congruent than neutral trials, whereas incongruent and neutral trials did not differ. These results imply that trial-by-trial changes in performance may not be driven solely by conflict, but rather by changes in attention triggered by congruent information.

Test–retest reliability of regional electroencephalogram (EEG) and cardiovascular measures in social anxiety disorder (SAD)

Although the search for psychophysiological manifestations of social anxiety has a rich history, there appear to be no published reports examining the reliability of continuous electrocortical measures that putatively index stress vulnerability and stress reactivity in socially anxious individuals. We examined the 1-week test–retest reliability of regional electroencephalogram (EEG) alpha asymmetry and power, respiratory sinus arrhythmia (RSA), heart period, and heart period variability measures at rest and during anticipation of an impromptu speech in 26 adults diagnosed with social anxiety disorder (SAD). Across the 1-week time period, we found medium-to-large correlations for regional EEG asymmetry and large correlations for regional EEG alpha power, RSA, heart period, and heart period variability measures at rest and during speech anticipation, before and after accounting for age and medication status. These results are similar to patterns observed in nonclinical samples and appear to provide the first documented evidence of test–retest reliability of psychophysiological measures that index central nervous system activity in socially anxious individuals. These findings also provide support for the notion that resting frontal EEG asymmetry and RSA constitute relatively stable individual differences in this clinical population.

EEG alpha power and methadone treatment

Event Abstract Back to Event EEG alpha power and methadone treatment Grace Y. Wang1, 2*, Trecia A. Wouldes3, Rob Kydd3 and Bruce R. Russell1, 2 1 The University of Auckland, School of Pharmacy, New Zealand 2 The University of Auckland, Centre of Brain Research, New Zealand 3 The University of Auckland, Department of Psychological Medicine, New Zealand Background: A small number of studies conducted mostly during the 70’s have examined EEG changes in patients undertaking methadone maintenance treatment (MMT) during resting states and have shown inconsistent effects of MMT on brain function. Some of the inconsistencies may have arisen because of differences in sample size and variations in the inclusion criteria of participants. Objective: The objective of this study was to address the limitations of earlier research by examining the effect of MMT on resting alpha rhythm using electroencephalography (EEG). Method: The average power of alpha (8-13 Hz) rhythm was measured in 32 MMT patients, 17 opiate users and 25 healthy volunteers. A one-way analysis of variance with group as a fixed factor with age and years of education entered as covariates tested the differences between groups. Post-hoc comparisons were Bonferroni corrected. Results: During the eyes open condition, a significantly higher alpha amplitude was found in active opiate users in contrast to healthy controls in the frontal (F=4.93, p=0.01), central (F=4.25, p=0.02), temporal (F=5.28, p=0.007) and parietal-occipital regions (F=3.85, p=0.03). There was no difference either between the MMT group and healthy controls or between the MMT and opiate groups. Furthermore, there were no group differences in alpha power during the eyes closed condition. Conclusion: The abnormal electrical neural activity presented in active opiate users may be minimised following chronic MMT. The normalising effect of MMT may be related to a low level of sustained activation of the opiate receptors with proper dosing of methadone. Acknowledgements Funding for this study was provided by New Zealand Pharmacy Education Research Funding (NZPERF) References Feinstein, B., & Hanley, J. (1975). EEG findings in heroin addicts during induction and maintenance on methadone [Research Support, U.S. Gov't, Non-P.H.S.]. Electroencephalography & Clinical Neurophysiology, 39(1), 96-99. Fingelkurts, A. A., Fingelkurts, A. A., Kivisaari, R., Autti, T., Borisov, S., Puuskari, V., Kähkönen, S. (2007). Composition of EEG Oscillations and their Temporal Characteristics International Journal of Psychophysiology. Fingelkurts, A. A., Fingelkurts, A. A., Kivisaari, R., Autti, T., Borisov, S., Puuskari, V., Kähkönen, S. (2009). Methadone restores local and remote EEG functional connectivity in opioid. International Journal of Neuroscience 119(9), 1469-1493. Lenn, N. J., Senay, E. C., Renault, P. F., & Deuel, R. K. (1976). Neurological assessment of patients on prolonged methadone maintenance [Research Support, U.S. Gov't, Non-P.H.S.]. Drug & Alcohol Dependence, 1(4), 305-311. Martin, W. R., Jasinski, D. R., Haertzen, C. A., Kay, D. C., Jones, B. E., Mansky, P. A., & Carpenter, R. W. (1973). Methadone--a reevaluation. Archives of General Psychiatry, 28(2), 286-295. Keywords: Methadone treatment, Opiates, Alpha power, resting EEG, opiate receptors Conference: ACNS-2012 Australasian Cognitive Neuroscience Conference, Brisbane, Australia, 29 Nov - 2 Dec, 2012. Presentation Type: Poster Presentation Topic: Other Citation: Wang GY, Wouldes TA, Kydd R and Russell BR (2012). EEG alpha power and methadone treatment. Conference Abstract: ACNS-2012 Australasian Cognitive Neuroscience Conference. doi: 10.3389/conf.fnhum.2012.208.00111 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: 25 Oct 2012; Published Online: 07 Nov 2012. * Correspondence: Ms. Grace Y Wang, The University of Auckland, School of Pharmacy, Auckland, New Zealand, g.wang@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 Grace Y Wang Trecia A Wouldes Rob Kydd Bruce R Russell Google Grace Y Wang Trecia A Wouldes Rob Kydd Bruce R Russell Google Scholar Grace Y Wang Trecia A Wouldes Rob Kydd Bruce R Russell PubMed Grace Y Wang Trecia A Wouldes Rob Kydd Bruce R Russell 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.

Increased Alpha (8–12 Hz) Activity during Slow Wave Sleep as a Marker for the Transition from Implicit Knowledge to Explicit Insight

The number reduction task (NRT) allows us to study the transition from implicit knowledge of hidden task regularities to explicit insight into these regularities. To identify sleep-associated neurophysiological indicators of this restructuring of knowledge representations, we measured frequency-specific power of EEG while participants slept during the night between two sessions of the NRT. Alpha (8-12 Hz) EEG power during slow wave sleep (SWS) emerged as a specific marker of the transformation of presleep implicit knowledge to postsleep explicit knowledge (ExK). Beta power during SWS was increased whenever ExK was attained after sleep, irrespective of presleep knowledge. No such EEG predictors of insight were found during Sleep Stage 2 and rapid eye movement sleep. These results support the view that it is neuronal memory reprocessing during sleep, in particular during SWS, that lays the foundations for restructuring those task-related representations in the brain that are necessary for promoting the gain of ExK.

Asymmetry in Resting Alpha Activity: Effects of Handedness

Study Aim: Frontal electroencephalographic (EEG) alpha band power during rest shows increased right, and/or de-creased left, hemisphere activity under conditions of state or trait withdrawal-associated affect. Non-right-handers (NRH) are more likely to have mental illnesses and dispositions that involve such withdrawal-related affect. The aim of the study was to examine whether NRH might be characterized by increased right, relative to left, hemisphere activity during rest. Methods: The present research investigated that hypothesis by examining resting EEG alpha power in consistently-right-handed (CRH) and NRH individuals. Results: In support of the hypothesis, NRH demonstrated de-creased right hemisphere alpha power, and therefore increased right hemisphere activity, during rest, compared to CRH. Conclusions: The study demonstrates further support for an association between increased right hemisphere activity and negative affect via an association between such EEG activity and NRH.

Central glucocorticoid receptor-mediated effects of the antidepressant, citalopram, in humans: A study using EEG and cognitive testing

Our previous work in cellular and animal models has shown that antidepressants activate glucocorticoid receptor (GR) translocation, induce GR down-regulation, and decrease GR-mediated effects in the presence of GR agonists. However, whether these effects can be extrapolated to the human brain is still unclear. In this study, the effects of four days of treatment with the antidepressant, citalopram (20 mg/day), or placebo, were assessed in a double-blind, placebo-controlled, cross-over study. Central GR-mediated effects were examined by the effects of a single dose of cortisol (30 mg, orally) on two measures known to be sensitive to glucocorticoid administration: EEG alpha power and working memory function. Twenty healthy male subjects aged between 18 and 33 years participated to the study. The results suggest that GR activation by antidepressants, and the subsequent decrease in GR-mediated effects in the presence of GR agonists, indeed occurs in the human brain. Specifically, pre-treatment with citalopram decreased the well-known ability of cortisol to increase EEG alpha power and to impair working memory: cortisol-induced increase in EEG alpha power was (anteriorly) +15 to +20% (p=0.01) after placebo and +5 to +8% (p>0.5) after citalopram; and cortisol-induced increase in working memory errors was (at level 12, on average) 2.50 vs. 4.55 (p<0.05) after placebo and 4.10 vs. 3.35 (p>0.05) after citalopram. No effects were detected on alerting. These results are consistent with the notion that citalopram treatment activates GR translocation and inhibits the functional consequences of the subsequent cortisol administration. Our study further emphasizes the importance of the GR as a target for antidepressant action in humans.

One night’s CPAP withdrawal in otherwise compliant OSA patients: marked driving impairment but good awareness of increased sleepiness

Obstructive sleep apnoea (OSA) patients effectively treated by and compliant with continuous positive air pressure (CPAP) occasionally miss a night's treatment. The purpose of this study was to use a real car interactive driving simulator to assess the effects of such an occurrence on the next day's driving, including the extent to which these drivers are aware of increased sleepiness. Eleven long-term compliant CPAP-treated 50-75-year-old male OSA participants completed a 2-h afternoon, simulated, realistic monotonous drive in an instrumented car, twice, following one night: (1) normal sleep with CPAP and (2) nil CPAP. Drifting out of road lane ('incidents'), subjective sleepiness every 200 s and continuous electroencephalogram (EEG) activities indicative of sleepiness and compensatory effort were monitored. Withdrawal of CPAP markedly increased sleep disturbance and led to significantly more incidents, a shorter 'safe' driving duration, increased alpha and theta EEG power and greater subjective sleepiness. However, increased EEG beta activity indicated that more compensatory effort was being applied. Importantly, under both conditions, there was a highly significant correlation between subjective and EEG measures of sleepiness, to the extent that participants were well aware of the effects of nil CPAP. Patients should be aware that compliance with treatment every night is crucial for safe driving.

Brain’s alpha activity is highly reduced in euthymic bipolar disorder patients

Brain's alpha activity and alpha responses belong to major electrical signals that are related to sensory/cognitive signal processing. The present study aims to analyze the spontaneous alpha activity and visual evoked alpha response in drug free euthymic bipolar patients. Eighteen DSM-IV euthymic bipolar patients (bipolar I n=15, bipolar II n=3) and 18 healthy controls were enrolled in the study. Patients needed to be euthymic at least for 4weeks and psychotrop free for at least 2weeks. Spontaneous EEG (4min eyes closed, 4min eyes open) and evoked alpha response upon application of simple visual stimuli were analyzed. EEG was recorded at 30 positions. The digital FFT-based power spectrum analysis was performed for spontaneous eyes closed and eyes open conditions and the response power spectrum was also analyzed for simple visual stimuli. In the analysis of spontaneous EEG, the ANOVA on alpha responses revealed significant results for groups (F(1,34)=8.703; P<0.007). Post-hoc comparisons showed that spontaneous EEG alpha power of healthy subjects was significantly higher than the spontaneous EEG alpha power of euthymic patients. Furthermore, visual evoked alpha power of healthy subjects was significantly higher than visual evoked alpha power of euthymic patients (F(1,34)=4.981; P<0.04). Decreased alpha activity in spontaneous EEG is an important pathological EEG finding in euthymic bipolar patients. Together with an evident decrease in evoked alpha responses, the findings may lead to a new pathway in search of biological correlates of cognitive impairment in bipolar disorder.