Electroencephalogram Power Research Articles

Can spectral power predict subjective sleep quality in healthy individuals?

The aim of this study was to assess the relationship between electroencephalogram (EEG) power spectral density and subjective sleep quality in healthy individuals. The sample was selected from the archival database of the Sleep Center at the Department for Psychiatry and Psychotherapy, Medical Center - University of Freiburg, and consisted of 206 healthy adults aged 19-73years (85 male, 121 female) who underwent a polysomnographic examination for two consecutive nights. A multivariate analysis of variance (MANOVA) with spectral power variables of different frequency bands as dependent variables and subjective sleep quality, night number, age and gender as independent variables was statistically significant for subjective sleep quality, age and gender, but not for night number. In subsequent separate ANOVAs, higher subjective sleep quality was significantly related to decreased non-rapid eye movement (NREM) stage 2 sigma 2 and rapid eye movement (REM) delta 1; however, the relation between REM delta 1 and sleep quality did not remain significant when REM duration was accounted for. The effect sizes of the correlations between sleep quality and spectral power were small (r=-0.1). In contrast to common assumptions, the amount of variance in subjective sleep quality that can be explained through EEG power spectral density variables is small. This finding indicates that subjective and objective sleep are different constructs, the interrelations of which are not yet well understood.

Light Modulation of Human Clocks, Wake, and Sleep.

Light, through its non-imaging forming effects, plays a dominant role on a myriad of physiological functions, including the human sleep–wake cycle. The non-image forming effects of light heavily rely on specific properties such as intensity, duration, timing, pattern, and wavelengths. Here, we address how specific properties of light influence sleep and wakefulness in humans through acute effects, e.g., on alertness, and/or effects on the circadian timing system. Of critical relevance, we discuss how different characteristics of light exposure across the 24-h day can lead to changes in sleep–wake timing, sleep propensity, sleep architecture, and sleep and wake electroencephalogram (EEG) power spectra. Ultimately, knowledge on how light affects sleep and wakefulness can improve light settings at home and at the workplace to improve health and well-being and optimize treatments of chronobiological disorders.

Shorter sleep durations in adolescents reduce power density in a wide range of waking electroencephalogram frequencies.

Despite sleep’s recognized biological importance, it has been remarkably difficult to demonstrate changes in brain physiology with reduced sleep durations. In a study of adolescents, we varied sleep durations by restricting time in bed for four nights of either 10, 8.5 or 7 h. Shorter sleep durations significantly decreased waking electroencephalogram (EEG) power in a wide range of frequencies with both eyes closed and eyes open in central and occipital leads. These findings suggest new research directions and raise the possibility that waking EEG power density could provide a non-invasive test for biologically sufficient sleep.

Modulation of brain alpha rhythm and heart rate variability by attention-related mechanisms.

According to recent evidence, oscillations in the alpha-band (8–14 Hz) play an active role in attention via allocation of cortical resources: decrease in alpha activity enhances neural processes in task-relevant regions, while increase in alpha activity reduces processing in task-irrelevant regions. Here, we analyzed changes in alpha-band power of 13-channel electroencephalogram (EEG) acquired from 30 subjects while performing four tasks that differently engaged visual, computational and motor attentional components. The complete (visual + computational + motor) task required to read and solve an arithmetical operation and provide a motor response; three simplified tasks involved a subset of these components (visual + computational task, visual task, motor task). Task-related changes in alpha power were quantified by aggregating electrodes into two main regions (fronto-central and parieto-occipital), to test regional specificity of alpha modulation depending on the involved attentional aspects. Independent Component Analysis (ICA) was applied to discover the main independent processes accounting for alpha power over the two scalp regions. Furthermore, we performed analysis of Heart Rate Variability (HRV) from one electrocardiogram signal acquired simultaneously with EEG, to test autonomic reaction to attentional loads. Results showed that alpha power modulation over the two scalp regions not only reflected the number of involved attentional components (the larger their number the larger the alpha power suppression) but was also fine-tuned by the nature of the recruited mechanisms (visual, computational, motor) relative to the functional specification of the regions. ICA revealed topologically dissimilar and differently attention-regulated processes of alpha power over the two regions. HRV indexes were less sensitive to different attentional aspects compared to alpha power, with vagal activity index presenting larger changes. This study contributes to improve our understanding of the electroencephalographic and autonomic correlates of attention and may have practical implications in neurofeedback, brain-computer interfaces, neuroergonomics as well as in clinical practice and neuroscience research exploring attention-deficit disorders.

Do green-blocking glasses enhance the nonvisual effects of white polychromatic light?

BackgroundIt is well known that light containing the blue component stimulates the intrinsically photosensitive retinal ganglion cells (ipRGCs) and plays a role in melatonin suppression and pupillary constriction. In our previous studies, we verified that simultaneous exposure to blue and green light resulted in less pupillary constriction than blue light exposure. Hence, we hypothesized that the nonvisual effects of polychromatic white light might be increased by blocking the green component. Therefore, we conducted an experiment using optical filters that blocked blue or green component and examined the nonvisual effects of these lights on pupillary constriction and electroencephalogram power spectra.MethodsTen healthy young males participated in this study. The participant sat on a chair with his eyes facing an integrating sphere. After 10 min of light adaptation, the participant’s left eye was exposed to white pulsed light (1000 lx; pulse width 2.5 ms) every 10 s with a blue-blocking glasses, a green-blocking glasses, or control glasses (no lens), and pupillary constriction was measured. Then, after rest for 10 min, the participant was exposed a continuous white light of 1000 lx with a blue- or green-blocking glasses or control glasses and electroencephalogram was measured.ResultsPupillary constriction with the blue-blocking glasses was significantly less than that observed with the green-blocking glasses. Furthermore, pupillary constriction under the green-blocking glasses was significantly greater than that observed with the control glasses.ConclusionsA reduction in the green component of light facilitated pupillary constriction. Thus, the effects of polychromatic white light containing blue and green components on ipRGCs are apparently increased by removing the green component.

Neurofeedback versus psychostimulants in the treatment of children and adolescents with attention-deficit/hyperactivity disorder: a systematic review.

This systematic review aimed to evaluate the efficacy of neurofeedback (NF) compared to stimulant medication in treating children and adolescents with attention-deficit/hyperactivity disorder (ADHD). Included in this review are eight randomized controlled trials that compared an NF condition, either alone or combined with medication, to a medication condition, which was mainly methylphenidate. Outcome measures included behavioral assessments by parents and teachers, self-reports, neurocognitive measures, electroencephalogram power spectra and event-related potentials. When only trials are considered that include probably blinded ratings or those that are sham-NF or semi-active controlled or those that employed optimally titration procedures, the findings do not support theta/beta NF as a standalone treatment for children or adolescents with ADHD. Nevertheless, an additive treatment effect of NF was observed on top of stimulants and theta/beta NF was able to decrease medication dosages, and both results were maintained at 6-month follow-up. This review concludes that the present role of NF in treating children diagnosed with ADHD should be considered as complementary in a multimodal treatment approach, individualized to the needs of the child, and may be considered a viable alternative to stimulants for a specific group of patients. Particularly patients with the following characteristics may benefit from NF treatment: low responders to medication, intolerable side effects due to medication, higher baseline theta power spectra and possibly having no comorbid psychiatric disorders. Future research should prioritize the identification of markers that differentiate responders from nonresponders to NF treatment, the potential of NF to decrease stimulant dosage, the standardization of NF treatment protocols and the identification of the most favorable neurophysiological treatment targets.

Chasing the zone: Reduced beta power predicts baseball batting performance

Mental state prior to sports skill execution is related to subsequent performance. For example, relationships between pre-performance electroencephalogram (EEG) power and subsequent movement outcomes in golf putting, pistol shooting, and basketball free throw shooting have been previously reported. With that said, the existing body of research examining the pre-performance EEG – performance relationship has been focused on the execution of internally as opposed to externally-paced motor skills. Given that the execution of internally and externally-paced movements are dependent on different neural pathways, in the present study we examined whether or not pre-performance EEG power predicted ensuing performance of an externally-paced motor skill – baseball batting. Sixty-seven baseball players had EEG data recorded for 120 s prior to batting practice. Performance was assessed by three expert coaches and the accuracy of coach performance ratings was verified via Generalizability Theory. An analysis of our data revealed an inverse relationship between frontal EEG power in the beta range and subsequent batting performance - reduced beta power was associated with better batting performance whereas increased beta power was associated with worse batting performance. Our results are in line with prior research that has demonstrated a relationship between increased EEG power in the beta range and the subsequent commitment of motor errors in addition to the aforementioned work examining pre-performance EEG and the execution of internally-paced motor skills.

How Old Is Your Brain? Slow-Wave Activity in Non-rapid-eye-movement Sleep as a Marker of Brain Rejuvenation After Long-Term Exercise in Mice.

Physical activity is beneficial for health. It has been shown to improve brain functioning and cognition, reduce severity of mood disorders, as well as facilitate healthy sleep and healthy aging. Sleep has been studied in healthy aged mice and absolute slow-wave-activity levels (SWA, electroencephalogram power between 0.75 and 4.0 Hz) in non-rapid-eye-movement sleep (NREM) were elevated, suggesting changes in brain connectivity. To investigate whether physical activity can diminish this aging-induced effect, mice of three age groups were provided with a running wheel (RW) for 1–3 months (6-months-old, n = 9; 18-months-old, n = 9; 24–months-old, n = 8) and were compared with control sedentary mice (n = 11, n = 8 and n = 9 respectively). Two weeks before the sleep-wake recordings the running wheels were removed. The electroencephalogram (EEG) and electromyogram were continuously recorded during undisturbed 24 h baseline (BL) and a sleep-deprivation was conducted during the first 6 h of the second day. Increased waking and decreased NREM sleep was found in the young RW mice, compared to young controls. These effects were not evident in the 18 and 24 months old mice. Unlike sleep architecture, we found that SWA was altered throughout the whole age spectrum. Notably, SWA was increased with aging and attenuated with exercise, exhibiting the lowest levels in the young RW mice. To utilize the cross-age revealing features of SWA, we applied machine learning techniques and found that characteristic information regarding age and exercise was enclosed in SWA. In addition, with cluster analysis, we could classify and accurately distinguish the different groups based solely on their SWA. Therefore, our study comprises a three-fold contribution: (a) effects of exercise on sleep are sustained following 2 weeks after removal of the wheel, (b) we show that EEG SWA can be used as a physiological marker of brain age in the mouse, (c) long-term voluntary regular age-matched exercise leads to a younger phenotype.

Optical probing of orexin/hypocretin receptor antagonists.

The present study investigated the function of Hypocretin (Hcrt or Orexin/OX) receptor antagonists in sleep modulation and memory function with optical methods in transgenic mice. We used Hcrt-IRES-Cre knock-in mice and AAV vectors expressing channelrhodopsin-2 (ChR2) to render Hcrt neurons sensitive to blue light stimulation. We optogenetically stimulated Hcrt neurons and measured latencies to wakefulness in the presence or absence of OX1/2R antagonists and Zolpidem. We also examined endogenous Hcrt neuronal activity with fiber photometry. Changes in memory after optogenetic sleep disruption were evaluated by the novel object recognition test (NOR) and compared for groups treated with vehicle, OX1/2R antagonists, or Zolpidem. We also analyzed electroencephalogram (EEG) power spectra of wakefulness, rapid eye movement (REM) sleep, and non-REM (NREM) sleep following the injections of vehicle, OX1/2R antagonists, and Zolpidem in young adult mice. Acute optogenetic stimulation of Hcrt neurons at different frequencies resulted in wakefulness. Treatment with dual OX1/2R antagonists (DORAs) DORA12 and MK6096, as well as selective OX2R antagonist MK1064 and Zolpidem, but not selective OX1R antagonist 1SORA1, significantly reduced the bout length of optogenetic stimulation-evoked wakefulness episode. Fiber photometry recordings of GCaMP6f signals showed that Hcrt neurons are active during wakefulness, even in the presence of OXR antagonists. Treatment with dual OX1/2R antagonists improved memory function despite optogenetic sleep fragmentation caused impaired memory function in a NOR test. Our results show DORAs and selective OX2R antagonists stabilize sleep and improve sleep-dependent cognitive processes even when challenged by optogenetic stimulation mimicking highly arousing stimuli.

Wavelet based features of EEG power spectra analysis in children with borderline intellectual functioning

Objective To investigate the features of absolute electroencephalogram (EEG) power spectra in children with borderline intellectual functioning (BIF) as well as their correlation with cognitive function and behavioral problems. Methods 30 children with borderline intellectual functioning and 42 typical developing children (TDC) were recruited in this study. All of them underwent the Chinese Revised Wechsler Intelligence Scale for Children (C-WISC) and their behavioral problems were assessed according to the Conners’ Parent Symptom Questionnaire (PSQ). Resting EEG of 128 electrodes were recorded when the participants closed their eyes and analyzed using wavelet transform to assess the absolute power of alpha, beta, theta, gamma and theta/beta ratio (TBR). Results (1)PSQ scores of BIF (conduct problems(0.78±0.16), learning problems(1.53±0.14), psychosomatic disorder(0.17±0.04), impulsivity-hyperactivit(1.13±0.14), anxious(0.52±0.08), hyperactivity inde(1.04±0.10))were higher than TDC(conduct problems(0.21±0.03), learning problems(0.35±0.05), psychosomatic disorder(0.07±0.02), impulsivity-hyperactivit(0.27±0.05), anxious(0.26±0.03), hyperactivity index(0.25±0.04)), and the difference was statistically significant(P<0.05). (2)alpha band: the main effects of the two groups on the left and right hemisphere (F=14.44, P<0.01)and the anterior and posterior hemispheres (F=29.54, P<0.01) were significant.The interaction effect between the left and right hemisphere and the anterior and posteriorm hemispheres was significant(F=8.55, P<0.01). The activity of the alpha wave was significant in the right posterior hemisphere.(3)The main effects of the two groups on the left and right hemispheres (F=6.49, P=0.01)and the anterior and posterior hemispheres(F=8.01, P=0.01) were significant.The two groups had significant interaction effects between the left and right hemisphere and the type(F=5.84, P=0.02). The interaction between the left and right hemisphere and anterior and posterior hemispheres was significant(F=10.51, P<0.01). The activity of the right anterior and right posterior parts was more significant.(4)delta band: the main effects of the two groups were significant in the anterior and posterior hemispheres(F=11.15, P<0.01), and the activities in the anterior hemisphere were larger than those in the posterior hemisphere.(5)TBR: the main effects of the two groups were significant in the anterior and posterior hemispheres(F=4.80, P=0.03). The TBR of the two groups was statistically significant in the right hemisphere(t=2.61, P=0.01). Conclusion The TBR activity of BIF on the right was higher than TDC.The increased TBR activity in the right hemisphere of BIF may be a neurobiological basis for cognitive impairment such as adaptive behavior disorder and executive function. Key words: Borderline intellectual functioning; EEG power spectra; Wavelet transform; Children

Childhood high-frequency EEG activity during sleep is associated with incident insomnia symptoms in adolescence.

Insomnia has been associated in cross-sectional studies with increased beta (15-35Hz) electroencephalogram (EEG) power during nonrapid eye movement (NREM) sleep, an index of cortical hyperarousal. However, it is unknown whether this cortical hyperarousal is present before individuals with insomnia develop the disorder. To fill this gap, we examined the association of childhood sleep high-frequency EEG activity with incident insomnia symptoms (i.e., absence of insomnia symptoms in childhood but presence in adolescence). We studied a case-control subsample of 45 children (6-11years) from the Penn State Child Cohort, a population-based random sample of 421 children, who were followed up after 8years as adolescents (13-20years). We examined low-beta (15-25Hz) and high-beta (25-35Hz) relative power at central EEG derivations during NREM sleep and, in secondary analyses, during sleep onset latency, sleep onset, and REM sleep. Incident insomnia symptoms were defined as the absence of parent-reported difficulty falling and/or staying asleep during childhood and a self-report of these insomnia symptoms during adolescence. Childhood high-beta power during NREM sleep was significantly increased in children who developed insomnia symptoms in adolescence (n=25) as compared to normal sleeping controls (n=20; p=.03). Multivariable-adjusted logistic regression models showed that increased childhood high-beta EEG power during NREM sleep was associated with a threefold increased odds (95% CI=1.12-7.98) of incident insomnia symptoms in adolescence. No other significant relationships were observed for other sleep/wake states or EEG frequency bands. Increased childhood high-frequency EEG power during NREM sleep is associated with incident insomnia symptoms in adolescence. This study indicates that cortical hyperarousal during sleep may be a premorbid neurophysiological sign of insomnia, which may mediate the increased risk of psychiatric disorders associated with insomnia.

Multivariate assessment of the central-cardiorespiratory network structure in neuropathological disease

Objective: The new interdisciplinary field of network physiology is increasingly becoming a focus of interest in medicine. Autonomic nervous system (ANS) dysfunction is well described in schizophrenia (SZO). However, the linear and nonlinear coupling between the ANS and central nervous system (CNS) has only been partly addressed until now. This coupling can be assumed to be a feedback-feedforward network, reacting with flexible and adaptive responses to internal and external factors. Approach: For the first time, in this study we investigated linear and nonlinear short-term central–cardiorespiratory coupling of 17 patients suffering from paranoid SZO in comparison to 17 age-gender matched healthy subjects analyzing heart rate (HR), respiration (RESP), and the power of frontal electroencephalogram (EEG) activity (PEEG). The objective is to determine how the different regulatory aspects of the CNS-ANS affect the central-cardiorespiratory network (CCRN). To quantify these couplings within the CCRN normalized short time partial directed coherence and the new multivariate high-resolution joint symbolic dynamics were applied. Main results: We found that the CCRN in SZO can be characterized as a bidirectional one, with stronger central driving mechanisms (PEEG → HR) towards HR regulation than vice versa, and with stronger respiratory influence (RESP → PEEG) on central activity than vice versa. This suggests that the central-cardiorespiratory process (closed-loop) is mainly focused on adapting the HR via the sinoatrial node than focusing on respiratory regulation. On the other hand, the feedback-loop from ANS to CNS is strongly dominated via respiratory activity. Significance: We demonstrated a considerably significantly different CCRN structure in SZO with a strong central influence on the cardiac system and a strong respiratory influence on the CNS. Moreover, this study provides a more in-depth understanding of the interplay of the central and autonomic regulatory network in healthy subjects and SZO patients.

Differences in Seizure Expression Between Magnetic Seizure Therapy and Electroconvulsive Shock.

Evidence suggests that magnetic seizure therapy (MST) results in fewer side effects than electroconvulsive treatment, both in humans treated with electroconvulsive therapy (ECT) as well as in the animal preclinical model that uses electroconvulsive shock (ECS). Evidence suggests that MST results in fewer cognitive side effects than ECT. Although MST offers enhanced control over seizure induction and spread, little is known about how MST and ECT seizures differ. Seizure characteristics are associated with treatment effect. This study presents quantitative analyses of electroencephalogram (EEG) power after electrical and magnetic seizure induction and anesthesia-alone sham in an animal model. The aim was to test whether differential neurophysiological characteristics of the seizures could be identified that support earlier observations that the powers of theta, alpha, and beta but not delta frequency bands were lower after MST when compared with those after ECS. In a randomized, sham-controlled trial, 24 macaca mulatte received 6 weeks of daily sessions while scalp EEG was recorded. Electroencephalogram power was quantified within delta, theta, alpha, and beta frequency bands. Magnetic seizure therapy induced lower ictal expression in the theta, alpha and beta frequencies than ECS, but MST and ECS were indistinguishable in the delta band. Magnetic seizure therapy showed less postictal suppression than ECS. Increasing electrical dosage increased ictal power, whereas increasing MST dosage had no effect on EEG expression. Magnetic seizure therapy seizures have less robust electrophysiological expression than ECS, and these differences are largest in the alpha and beta bands. The relevance of these differences in higher frequency bands to clinical outcomes deserves further exploration. Contrasting EEG in ECS and MST may lead to insights on the physiological underpinnings of seizure-induced amnesia and to finding ways to reduce cognitive side effects.

Etiopathogenetic neuroreparative therapy of encephalopathies

The possibility of neural tissue regeneration in encephalopathies of various genesis by influencing brain cell pool with reduced functional activity in the state of parabiosis is discussed. The use of a neuroprotective agent rekognan (citicoline) is a justified etiopathogenetic therapy realizing its effects through mechanisms of synthesis of membrane phospholipids, inhibition of synthesis of phospholipase A2, restoration of Na+/K+-adenosine triphosphate functioning, blocking of oxidative stress and apoptosis, modulation of choline, dopamine and glutamatergic neurotransmission. Electroencephalography study was made in order to investigate reactivity of a brain in 12 patients (6 men and 6 women, average age 57±11 years) with encephalopathies to treatment with the Rekognan. The relative index - K α/θ spectra of electroencephalogram power - was used to assess the dynamics of the functional state of a brain before and after the course of treatment with a neuroprotective agent. The majority of patients (9 patients) had a statistically significant positive electrophysiological dynamics with an average increase of K α/θ by 64%. Deprivation of the focus of irrigation in the form of a «running» of reduced acute waves in the right temporal region was recorded in one case, revealed during the test with hyperventilation. An additional prescription for the main therapy of the course of the recognan is associated with an increase in the power of electroencephalogram spectra in a frequency of the dominant alpha rhythm in 75% of patients with encephalopathies of different etiology. Favorable dynamics K α/θ spectra of electroencephalogram power testifies to the involvement of the cerebral reserve due to the neuroreparative effect of recognan.

Automatic artefact detection in single‐channel sleep EEG recordings

Quantitative electroencephalogram analysis (e.g. spectral analysis) has become an important tool in sleep research and sleep medicine. However, reliable results are only obtained if artefacts are removed or excluded. Artefact detection is often performed manually during sleep stage scoring, which is time consuming and prevents application to large datasets. We aimed to test the performance of mostly simple algorithms of artefact detection in polysomnographic recordings, derive optimal parameters and test their generalization capacity. We implemented 14 different artefact detection methods, optimized parameters for derivation C3A2 using receiver operator characteristic curves of 32 recordings, and validated them on 21 recordings of healthy participants and 10 recordings of patients (different laboratory) and considered the methods as generalizable. We also compared average power density spectra with artefacts excluded based on algorithms and expert scoring. Analyses were performed retrospectively. We could reliably identify artefact contaminated epochs in sleep electroencephalogram recordings of two laboratories (healthy participants and patients) reaching good sensitivity (specificity 0.9) with most algorithms. The best performance was obtained using fixed thresholds of the electroencephalogram slope, high-frequency power (25-90Hz or 45-90Hz) and residuals of adaptive autoregressive models. Artefacts in electroencephalogram data can be reliably excluded by simple algorithms with good performance, and average electroencephalogram power density spectra with artefact exclusion based on algorithms and manual scoring are very similar in the frequency range relevant for most applications in sleep research and sleep medicine, allowing application to large datasets as needed to address questions related to genetics, epidemiology or precision medicine.

Associations between quantitative sleep EEG and subsequent cognitive decline in older women.

The pathophysiological processes of Alzheimer's dementia predate its clinical manifestation. Sleep disturbances can accelerate the aging process and are common features of dementia. This study examined whether quantitative sleep electroencephalogram changes predate the clinical development of mild cognitive impairment and/or incident dementia. We collected data from a nested case-control sample of women (mean age 83years) from the Sleep and Cognition Study, an ancillary study to the longitudinal Study of Osteoporotic Fractures, who were characterized as cognitively normal at the time of a baseline polysomnography study (Study of Osteoporotic Fractures visit 8) based on a Mini-Mental Status Exam (MMSE) score >24. Cases (n=85) were women who developed new mild cognitive impairment or dementia by objective cognitive testing 5years after polysomnography. Controls were women with no mild cognitive impairment/dementia (n=85) at baseline or at follow-up. Differences in electroencephalogram absolute and relative power density were observed between the two groups. Specifically, higher electroencephalogram power values were found in the dementia/mild cognitive impairment group, for the alpha (p=.01) and theta bands (p=.04) in non-rapid eye movement sleep, as well as alpha (p=.04) and sigma (p=.04) bands in rapid eye movement sleep. In contrast, there were no group differences in traditional polysomnography measures of sleep architecture and sleep stage distribution, as well as sleep apnea and periodic limb movement indices. Our results provide evidence for quantitative electroencephalogram changes, which precede the clinical onset of cognitive decline and the diagnosis of dementia in elderly women, and support the application of quantitative sleep electroencephalogram analysis as a promising biomarker for imminent cognitive decline.

Increased EEG Theta Spectral Power in Sleep in Myotonic Dystrophy Type 1.

Myotonic dystrophy type 1 (DM1) is a multisystemic disorder that involves the central nervous system (CNS). Individuals with DM1 commonly present with sleep dysregulation, including excessive daytime sleepiness and sleep-disordered breathing. We aim to characterize electroencephalogram (EEG) power spectra from nocturnal polysomnography (PSG) in patients with DM1 compared to matched controls to better understand the potential CNS sleep dysfunction in DM1. A retrospective, case-control (1:2) chart review of patients with DM1 (n = 18) and matched controls (n = 36) referred for clinical PSG at the Stanford Sleep Center was performed. Controls were matched based on age, sex, apnea-hypopnea index (AHI), body mass index (BMI), and Epworth Sleepiness Scale (ESS). Sleep stage and respiratory metrics for the two groups were compared. Power spectral analysis of the EEG C3-M2 signal was performed using the fast Fourier transformation. Patients with DM1 had significantly increased theta percent power in stage N2 sleep compared to matched controls. Theta/beta and theta/alpha percent power spectral ratios were found to be significantly increased in stage N2, N3, all sleep stages combined, and all wake periods combined in patients with DM1 compared to controls. A significantly lower nadir O2 saturation was also found in patients with DM1 versus controls. Compared to matched controls, patients with DM1 had increased EEG theta spectral power. Increased theta/beta and theta/alpha power spectral ratios in nocturnal PSG may reflect DM1 pathology in the CNS.

Predictive power of abnormal electroencephalogram for post-cerebral infarction depression.

Electroencephalography is a sensitive indicator for measuring brain condition, and can reflect early changes in brain function and severity of cerebral ischemia. However, it is not yet known whether electroencephalography can predict development of post-cerebral infarction depression. A total of 321 patients with ischemic stroke underwent electroencephalography and Hamilton Depression Rating Scale assessment to analyze the relationship between electroencephalography and post-cerebral infarction depression. Our results show that electroencephalograms of ischemic stroke patients with depression exhibit low-amplitude alpha activity and slow theta activity. In contrast, electroencephalograms of ischemic stroke patients without depression show fast beta activity and slow delta activity. These findings confirm that low-amplitude alpha activity and slow theta activity can be considered as independent predictors for post-cerebral infarction depression.

Peak frequency analysis for schizophrenia using electroencephalogram power spectrum during mental activity

Peak frequency analysis for schizophrenia using electroencephalogram power spectrum during mental activity

Peak frequency analysis for schizophrenia using electroencephalogram power spectrum during mental activity

The objective of this work is to identify schizophrenia using electroencephalogram spectral feature. This work proposes two oddball paradigms to stimulate mental activity for cognitive process and EEG is recorded during both rest and mental activity. EEG from 51 schizophrenia and 26 normal subjects are used in this work. The maximum power in various bands and its corresponding frequency are estimated from the EEG power spectrum and are called as peak power and peak frequency, respectively. Statistical evaluations are made using Student's t-test and ANOVA. Theta peak frequency, beta peak frequency and beta peak power, all with a low value of p (p < 0.001) and alpha peak power with p < 0.01 during mental activity are identified as most significant features. SVM classifier designed with these features has a classification accuracy of 91.75% which shows that EEG can be used as a clinical tool to detect schizophrenia.