Frequency Of Alpha Rhythm Research Articles

Прогнозування ризику розвитку розладів аутистичного спектра в дітей з епілептичними енцефалопатіями

Predicting the risk of developing autism spectrum disorders (ASD) in children with epileptic encephalopathies (EE) is an important task, which makes it possible to identify the most significant risk factors and develop ways of their modification. Purpose - to develop a model for predicting the risk of developing ASD in young children with EE. Materials and methods. 75 children aged 0-3 years with the onset of epileptic seizures in the first year of life, clinical manifestations of EE were examined. The most informative clinical, neurophysiological, and neuroimaging indicators for predicting the risk of clinical manifestations of ASD were determined: age of onset of epileptic seizures, index of spike-wave activity during NREM sleep, frequency and amplitude of alpha rhythm, frequency and amplitude of epileptiform activity, fractional anisotropy and mean diffusion coefficient in the Broca’s center, fractional anisotropy in the Wernicke center and knee of the corpus callosum. The multiple linear regression method was used to predict the risk of developing ASD symptoms. Results. A model for predicting the risk of developing clinical manifestations of ASD in children with EE has been developed. It was established that the risk of developing clinical manifestations of ASD increases with a decrease in the age of onset of epileptic seizures, decrease in the frequency and amplitude of the alpha rhythm according to electroencephalography (EEG) data, increase of the index of spike-wave activity, frequency and amplitude of epileptiform activity, increase in the index of fractional anisotropy in the anterior part of the arcuate tract, decrease in the average diffusion coefficient in the area of the Broca’s center, fractional anisotropy in the Wernicke center and the knee of the corpus callosum according to magnetic resonance tractography. Conclusions. A regression model for predicting the risk of clinical manifestations of ASD in children with EE was developed with an average error of approximation of 13.2% and a coefficient of determination of 0.74, which is recommended for use in clinical practice in order to form groups of children at high risk of ASD. Such children require further dynamic monitoring and early intervention by specialists of a multidisciplinary team for timely identification and correction of ASD symptoms The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of the participating institution. The informed consent of the patient was obtained for conducting the studies. No conflict of interests was declared by the author.

ELECTROENCEPHALOGRAPHIC MARKERS OF CNS FUNCTIONAL STATE IN SPORT

All over the world, sports professionals are interested in attracting new technologies to work-out sessions to increase sportsmanship. Literature reveals that EEG markers of cognitive function dynamics, sensorimotor integration, and psychological stability are important in assessing the functional state of athletes. In addition to a high level of physical fitness, elite athletes develop cognitive skills specific to a particular sport. Besides they demonstrate high sensorimotor integration, improved attention, perception and information processing and other characteristics ensuring high performance. The review systematically analyzes publications devoted to the correlation between physical activity and CNS functional state. It is established that indicators of EEG alpha rhythm power and frequency are significant neurophysiological markers of cognitive function state. These indicators contribute much to studying high- and low-intensity physical activity.
 The authors analyzed such databases as Medline, Web of Science, Scopus, Pubmed, Cochrane, Embase, Google Scholar, and eLIBRARY.

Особливості порушення біоелектричної активності головного мозку у пацієнтів з печінковою енцефалопатією

The purpose of the study was to determine the relationship between the bioelectrical activity of the brain and the severity of hepatic encephalopathy. Materials and methods. We examined 99 patients with hepatic encephalopathy due to chronic hepatitis (51 patients, including 26 men and 25 women) and liver cirrhosis (48 patients, including 32 men and 16 women). The age of patients is 51.2±9.5 years. According to outpatient cards, all patients were examined in the gastroenterology departments of clinics in Kharkiv, where chronic hepatitis and liver cirrhosis and their etiology, if necessary, were diagnosed based on clinical-laboratory and instrumental examination. The term of chronic hepatitis from diagnosis was 8.1±3.9 years, liver cirrhosis – 2.1±0.5 years. The bioelectrical activity of the brain was recorded on a 12-channel computer electroencephalographic complex DX-NT32 in a state of restful wakefulness and under functional loads. Results. The increase in the severity of hepatic encephalopathy was accompanied by a decrease in the frequency and percentage contribution of alpha rhythm in combination with an increase in the percentage contribution to slow wave activity. The presence of a number of pathological changes that were detected on the electroencephalogram in the studied group of patients with hepatic encephalopathy is also noteworthy. Thus, in patients with stage II hepatic encephalopathy, bilateral synchronous acute "three-phase waves" were registered, mainly in the front-temporal leads. To determine the relationship between impaired bioelectrical activity of the brain and impaired liver function, a correlation was made between the indicators of electroencephalogram and the content of ammonia in the blood in groups of patients with chronic hepatitis and cirrhosis. The correlation analysis revealed a negative relationship between the content of ammonia in the blood and the frequency of the alpha rhythm (r = -0.58; r = -0.69; p <0.05), a direct relationship between the content of ammonia and the percentage contribution of slow wave activity (r = + 0.61; r = + 0.63, p <0.05) in groups of patients with chronic hepatitis and liver cirrhosis, respectively. The data obtained support the link between impaired brain bioelectrical activity and liver dysfunction due to chronic hepatitis and liver cirrhosis. Conclusion. Thus, electroencephalogram in a comprehensive examination of patients with chronic liver disease can track the dynamics of the clinical course of hepatic encephalopathy, and the changes on the electroencephalogram can serve as an additional marker of the severity of hepatic encephalopathy, which is especially important in detecting hepatic encephalopathy in the latent stage

EEG-correlates of work efficiency level among young persons with stress-induced bruxism

Purpose of the study. To establish the relationship between neurophysiological status and the level of efficiency in young people with bruxism.Materials and methods. Two groups of 64 and 53 subjects (males and females) aged 20–35 years old with bruxism and non-bruxers were formed according to questionnaire results and physical examination. The level of efficiency was assessed by the results of sensorimotor tracking of a moving object (the ‘Smile’ model). Spectral analysis was performed for evaluation of the baseline electroencephalograms. Microsoft Excel and Statistica 10.0 programs were used for statistical data processing.Results. The level of efficiency was statistically significantly lower in the hardest test of Smile model among the individuals with bruxism (p < 0.05). The bruxers also demonstrated a significantly lower dominant frequency and maximum amplitude of alpha-rhythm (p < 0.05), and significantly higher dominant frequency of beta2 rhythm (p < 0.05). The dominant frequency and the maximum amplitude of the alpha-rhythm are parameters corresponding to significant coefficients of the regression analysis. A negative relationship was found between the degree of error during sensorimotor tracking and the frequency and amplitude of alpha-rhythm.Conclusion. Regression models present the relationship between the level of efficiency and the alpha-rhythm severity. The regression equations make it possible to determine the functional state of the subject using an electroencephalogram.

Динамика частоты альфа-ритма ЭЭГ при слуховом восприятии действий и ее связь с уровнем интеллекта у детей 7–10 лет

A number of studies have shown the possibility of taking the EEG individual alpha peak frequency (IAPF) as an informative neurophysiological indicator of the overall cognitive efficiency of the human brain. The main goal of the present work was to study the IAPF reactivity in primary school age children in the process of auditory perception of sounds accompanying familiar instrumental movements, and to measure its hypothesized correlation to the verbal and non-verbal intelligence development. The effects of gender and age of children on these interrelations have also been estimated. We analyzed the data pertaining to the sample of primary school children aged 7-10 years (62 subjects). To assess possible age-related effects, the sample of children was additionally divided into two groups aged 7-8 years (24 boys and10 girls) and 9-10 years (14 boys and 14 girls). During the experiment, the subject and the experimenter sat at the adjacent places, with a monitor and a computer mouse (CM) placed on the table in front of each of them. A video showing the CM section of the experimenter’s table was displayed on the monitor screen in front of the subject. Experimental tasks comprised a series of stages (30 s each) including the conditions of a passive visual fixation on the video image of a motionless CM, execution of self-paced circular right-hand movements with CM, observation of similar movements produced by the experimenter, real-time imitation of the experimenter’s movements, wakeful rest with eyes closed, and auditory perception of familiar sounds accompanying the CM movements produced by the experimenter (subject’s eyes still closed). In the context of the present study, we analyzed the EEG dynamics in subjects during the two final stages with eyes closed: wakeful rest (WR) and auditory perception (AP) of familiar CM movements produced by the experimenter. The area of interest in the present study was the electrical activity of the laterally located parietal (P3, P4) and occipital (O1, O2) EEG electrodes. IAPF values were calculated for each of them within 7-13 Hz frequency range and averaged for the sum of them for the two corresponding experimental stages. The reactivity of the alpha rhythm frequency was calculated for each subject separately as the difference between the values of the dominant alpha rhythm frequency in two situations: the auditory perception of instrumental movements and the wakeful rest. Positive values of the frequency reactivity indicated its increase under condition of auditory perception of movements, and negative values - its decrease. The intelligence development levels of the participants were assessed with the help of the Wechsler test for children (WISC). In the context of the present study, the verbal and non-verbal intelligence scores were analyzed separately. We can conclude that in the primary school age children, the individual frequency of the parieto-occipital alpha rhythm in boys does not differ significantly between the groups aged 7-8 and 9-10 years. In girls, in the older group this indicator has a significantly higher value (See Table 1). For children aged 7-10 years, a significant positive correlation was identified between IAPF and non-verbal intelligence score. No connection with verbal intelligence has been found (See Fig. 1). The condition of auditory perception of sounds accompanying familiar instrumental actions evokes the decrease in the parieto-occipital alpha rhythm frequency in the majority of primary school age children, which is most characteristic for the groups of girls aged 9-10 years (See Table 2). A relatively small percentage of children (~ 18%) who demonstrated an increase in the frequency of the parieto-occipital alpha rhythm under condition of auditory perception of familiar instrumental actions, are characterized by lower scores of nonverbal intelligence, relative to their peers (See Fig. 2). Thus, nonverbal intelligence development can be related to the individual developmental characteristics of neural network oscillators, which can be reflected in children as multidirectional reactions in alpha rhythm frequency.

Statins in preventing stroke

Abstact. The results of a comprehensive analysis of Simvastatin (at a dose of 20 mg per day) on the functional state of the brain in patients with atherothrombotic ischemic stroke are presented. Simvastatin provokes vasoactive action (increases linear rate of systolic blood flow velocity (LBFVsys) and decreases peripheral resistance in separate vessels of the carotid and vertebra-basilar basins), posseses antiatherogenic action (a drug decrease in the intima size, in the frequency of the atherosclerotic plagues, in the level of cholesterol, triglycerides and low density lipoproteids (LDLs). This medication leads to a positive reorganization of the bioelectric activity of the brain (increases the frequency of alpha rhythm and decreases the power of the slow rhythms), being more marked in the patients with a left-sided ischemic localization. Complex positive effects of the Simvastatin on the cerebral hemodynamic, bioelectric activity of the brain and lipid metabolism in the patients after athrothrombotic ischemic stroke allow us to recommend Simvastatin not only for the secondary prevention of stroke but also for the correction of CNS functioning in stroke patients during their rehabilitation. Key words: ischemic stroke; statins; bioelectric activity of the brain; cerebral blood flow; atherothrombotic ischemic stroke

Effects of antiepileptic drugs on electroencephalography (EEG): Insights and applicability

ObjectiveThe objective of the study was to assess the effects of antiepileptic drugs (AEDs) on posterior alpha rhythm and determine whether they produce pathological slow waves in patients with epilepsy. MethodsOutpatient electroencephalographs (EEGs) in alert patients were selected. The three compared groups include 1) patients with an interested AED (monotherapy or combined with other AEDs); 2) patients with AEDs other than the interested AED; and 3) patients who did not take AEDs. Outcomes were frequency of posterior alpha rhythm and presence of generalized continuous (CSWs) and generalized intermittent slow waves (ISWs). Analysis of variance was used to assess which AED was associated with slower posterior alpha rhythm. Chi-square and logistic regression were employed to assess association and odds ratio (OR) with 95% confidence interval (CI) between pathological generalized slow waves and each AED. ResultsAmong 1050 EEG tracings, 638 EEGs met our criteria. Electroencephalographs requested because of cognitive decline and psychiatric symptoms were excluded, leaving 616 EEGs for analysis. Four hundred thirty-seven patients received at least one AED, whereas the remaining 179 patients did not take AED. Conventional AEDs [carbamazepine (CBZ), p = 0.024; phenobarbital (PB), p = 0.013; phenytoin (PHT), p = 0.001] except valproic acid (VPA) were associated with slower alpha frequency. Carbamazepine [adjusted OR: 5.74 (95% CI: 2.07, 15.94)] and PB [adjusted OR: 2.58 (95% CI: 1.15, 5.78)] were significantly associated with generalized ISWs. None were associated with generalized CSWs. ConclusionsPhenytoin, CBZ, and PB are associated with slower posterior alpha frequency. The latter 2 AEDs also produced pathological generalized ISWs. Valproic acid, benzodiazepines, and new-generation AEDs are not associated with either outcome. The presence of generalized ISWs in patients taking CBZ or PB should be cautiously interpreted since there can be drug effects. Association with cognitive side effects of these slow waves should be further studied.

Individual Features in the Typology of the Nervous System and the Brain Activity Dynamics of Freestyle Wrestlers Exposed to a Strong Physical Activity (A Pilot Study).

Nowadays, knowledge of psychophysiological features, particularly on the nervous system’s characteristics, is essential in the sporting context, particularly for freestyle wrestling. The study aimed to investigate the peculiarities of the wrestlers’ nervous system—on the individual and electrophysiological levels in two functional states—in calm wakefulness and during intense physical fatigue. Psychological (Well-being, Activity, Mood; Spielberger–Hanin; Leonhard’s questionnaires), as well as electrophysiological techniques (dynamics of the dominant and average frequencies of the main electroencephalogram (EEG) spectra—theta, alpha, low and high-frequency beta rhythms), were used in the study. It was shown that athletes were mainly characterized by the hyperthymic type of character accentuation and a low frequency of theta rhythm in a calm wakefulness state. After the acute physical load, wrestlers with high hyperthymia showed a moderate increase in theta, whereas other athletes showed a decrease in this parameter. Regardless of the level of hyperthymic accentuation, all wrestlers were characterized by an increase in the frequency of alpha rhythm after exercises in the left hemisphere. These results suggest the existence of a particular functional system in freestyle wrestlers, which allows the body’s regulatory systems to be adapted for the effective implementation of sports activity.

P37-F Predictors of cognitive impairment in patients with mine blast injury

Background Mine blast injury is accompanied by traumatic brain injury (TBI) in 60–100% of cases. TBI is associated with cognitive impairment (CI). However, predictors of CI in this patients (pts) are studied insufficiently. Material and methods 115 men aged 18 to 45 years with mild TBI caused by using of mine-blasting weapons. Cognitive functions were evaluated by using MoCA test, HADS scale. Cognitive dysfunction was defined as MoCa ⩽ 25 scores. Besides routine examination, neurophysiological methods such as quantitative electroencephalography (qEEG) and cognitive evoked potentials P300 (CEP P300), were performed. Results. In binary logistic regression predictors CI were complaints on headache and fatigability (OR 2.52, 95% CI 2.6–59.7, p = 0.02), increased tendon reflexes (OR, 2.6, 95% CI 1.24–2.32, p = 0.017), higher HADS anxiety level (OR-1.8, 95% CI 1.59–2.2, p = 0.04), changes of alpha rhythm frequency (OR-1.02, 95% CI 1.01–1.04, p = 0.004), decrease of alpha rhythm amplitudes (OR - 1.07, 95% CI 1.03–1.11, p Conclusions changes in qEEG and CEP P300 parameters are reliable independent predictors of CI in pts with TBI affected by mine blast trauma.

MEG recordings of patients with cerebral palsy before and after the application of pico-Tesla weak magnetic fields.

MEG data for five cerebral palsy patients were taken using a whole-head 122-channel MEG system. An experiment was designed to identify the possible effect of external pico-Tesla weak magnetic fields. The subjects were five male volunteers 17-46 years of age. External stimulation, field amplitude 1-7.5 pico-Tesla, was applied to each subject at their alpha-rhythm frequency. Fast Fourier transforms were applied to the data of all MEG channels and the rhythms of the patients were evaluated before and after pico-Tesla transcranial magnetic stimulation. The appliance of pico-Tesla weak magnetic fields showed the brains of the cerebral palsy patients had an enhance of the frequencies of (2-7 Hz) for each patient. This was followed by an improvement and normalization of their MEG. The results had a statistical significance in four out of five subjects (80%) and suggested the stimulation provided a positive contribution to the management of the symptoms of cerebral palsy patients.

Coherence of EEG Frequency Components While Performing Alternative Finger Movements in Women with Different Modal Frequency of Alpha-rhythm

A test group consisting of 113 right-hand healthy women from the ages of 19 to 21 was divided into two groups according to the average magnitude of their individual modal α- frequency – groups with high and low values of individual modal α- frequency. The ideal time of a simple sensorimotor reaction and choice-point behavior as well as speed capabilities of nervous processes during the tapping test, and measures of the coherence of EEG frequency components individually determined for each testee in quiescent intervals and while performing alternative movements by the right hand fingers were evaluated. Women with high modal α-frequency had better speed capabilities of nervous processes. Women with a high IαF had a less time of simple and complex reactions. The increase of coherence coefficients was seen throughout the EEG frequency spectrum in women performing alternate movements by fingers. Alternate movements of fingers performed by women with low α-frequency are provided by even higher frequency coherence of the EEG components in frontal, anterior temporal and central areas and by much lower frequency in the posterior temporal and parietal-occipital cortex areas compared to testees with high α-frequency.

Dynamics of Alpha Rhythm Peak Frequency during Falling Asleep.

Changes in the frequency characteristics of EEG alpha rhythm in during falling asleep were studied in three healthy individuals under conditions of long-term isolation (MARS-500 project). Falling asleep was preceded by enhanced alpha rhythm frequency. An inverse correlation between the duration of falling asleep and prevailing alpha rhythm frequency during active and relaxed wakefulness was revealed in the left hemisphere. These results demonstrate the principal possibility of predicting the duration of falling asleep by using alpha rhythm spectral analysis. It is assumed that the frequency of the alpha range spectral peak can be a marker of drowsiness and reflect the current need for sleep.

Discretized Theta-Rhythm Perception Revealed by Moving Stimuli

Despite the subjective continuity of perception over time, increasing evidence suggests that the human nervous system samples sensory information periodically, a finding strongly exemplified by discretized perception in the alpha-rhythm frequency band. More recently, studies have revealed a theta-band cyclic process that manifests itself as periodical fluctuations in behavioral performance. Here, we used a simple stimulus to demonstrate that the theta-cyclic system can produce a vivid experience of slow discrete visual sampling: a Gabor texture pattern appears as a series of flickering snapshots if its spatial window moves continuously over a carrier grating that remains still or drifts continuously in the opposite direction. While the perceptual magnitude of this illusory saltation varied with the speed difference between grating and window components in head-centered coordinates, the perceived rhythm of saltation remained nearly constant (3–8 Hz) over a wide range of stimulus parameters. Results provide further evidence that the slow cyclic neural processes play a critical role not only in attentional task performance but also in conscious perception.

P3-3-10. Electroencephalographic findings of central nervous system symptoms after human papillomavirus vaccine

Little is known about the mechanism of central nervous system (CNS) symptoms after human papillomavirus (HPV) vaccine, and there is no report on electroencephalographic (EEG) findings about these symptoms. This study shows postictal and interictal EEG findings of two girls with CNS symptoms after HPV vaccine. Case1: a 16-year-old girl. Her attack was left dominant dystonia followed by loss of consciousness. Her interictal EEG showed unilateral (the right side) loss of a photic driving response, B(I) RDs (Brief Potentially Ictal Rhythmic Discharges) on T6 electrode. Her postictal EEG showed asymmetric alpha rhythm amplitude (suppression of the left side; the left was less than 50% of the right). This asymmetry disappeared within 5 min EEG recordings. Case2: a 19-year-old girl. Her attack was right dominant dystonia followed by loss of consciousness. Her interictal EEG showed the left dominant incomplete alpha blocking, asymmetric alpha rhythm frequency (the left side was slower). Trihexyphenidyl was effective in reducing attacks of these patients. These EEG findings look like hemiplegic migraine, epilepsy, so the mechanism of CNS symptoms after HPV vaccine may be similar to these disorders. This study demonstrates objective findings about CNS symptoms (dystonia, loss of consciousness) after HPV vaccine, and that these symptoms are not functional/psychogenic disorders.

Modeling of Multifactor Regression of the Synchronization Period for an Individual Pattern of the Human Brain Neural Network

We consider multifactor model of the human brain synchronization depending on external factors (frequency and index of alpha rhythm, interhemispheric asymmetry and type of neural network of the head brain). All statistical data were obtained with the help of device Neuron-Spectrum (Neurosoft, Russia), which carried out multichannel registration of EEG (electroencephalogram) by 8 cup electrodes connected with ear electrodes and localized in accordance with the system 10-20. We consider the following two groups of subjects: people who regularly practice psycho-physical relaxation (meditation) and aged 22-34, and people who do not practice psycho-regulation and aged 22-38. The testing of the constructed models for the Control group proves an importance of all investigated factors and gives a mean absolute percentage error 0.53 %. Also, the coefficient of determination showed that 99.9 % of dispersion of the investigated feature is explained by the considered external factors. For the PPR (psycho-physical relaxation) group, we prove an importance of only one of the considered factors (frequency of alpha rhythm). Therefore, for this group, an additional research is needed to search for more significant external factors.

P274 Pleasant and unpleasant sound perception in patients with severe and moderate TBI using correlation dimension D2 analysis

Objectives Post-traumatic emotional disorder event is a major cause of slow rehabilitation worldwide. The present study investigates the effects of pleasant and unpleasant sound stimulation at different groups of subjects with TBI. At the base of our research strategy, we had used a group with diffuse axonal injury (DAI). Neurophysiology trials aim was to determine the processes that accompany emotional changes within traumatic brain damage. Methods All the following processing was performed using EEGLab plugin for MatLab. We’ve calculated D2 of the examined signal bandpass-filtered in the whole range of interest (2–20 Hz). Filtering was conducted using forward FFT, zeroing some samples and then reverse FFT. D2 was calculated using Higuchi algorithm (Higuchi, 1998). Results Our results showed that the correlation dimension D2 was significantly lower in severe TBI compared to healthy participants at a frequency of alpha rhythm during sound stimulation, especially unpleasant sounds. Discussion Meanwhile we found group differences of common correlation dimension in the parietal occipital region as much as possible to the sound of barking and crying. This result can support the previous data showed the prevalent respond to negative stimulation in patients in coma. Conclusions The high meaning of correlation dimension D2 is associated with higher entropy of EEG. Significance Recent studies have shown that the clinical assessment of mental recovery post-traumatic patients does not reflect the narrowing of the emotional respond and greatly lower.

Comparative study of the frontal EGG activity after superficial neuro-stimulation application, mindfulness and other attentional techniques

IntroductionChanges in the electrical cerebral activity, especially in frontotemporal regions, have been described after using the Superficial Neurostimulation Application (SNSA) in upper and lower limbs. The use of this technique is associated with emotional equilibrium and predisposition for a positive mood. Its application clinically improves hostility and anxiety symptoms.AimsTo compare the electrical changes observed after the use of SNSA with other techniques of mental concentration: Mindfulness (mental attention without judgment) and a technique based on the emission of a sound.Materials and methodsSNSA topology system: uses electricity through superficial electrodes placed on feet and hands and an electrode over the 7th cervical vertebra; Digital encephalogram; Faraday cage.ResultsMindfulness and SNSA techniques show similarities regarding the alpha rhythm's frequency in frontal regions (Figs. 1 and 2) compared to a different mental concentration technique (Fig. 3).ConclusionFurther analysis would be required.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Changes of EEG power spectrum in response to the emotional auditory stimuli in patients in acute and recovery stages of TBI (traumatic brain injury)

We investigated variability of responses to emotionally important auditory stimulation in different groups of TBI (Traumatic Brain Injury) in acute state or recovery. The patients sampling consisted of three different groups: patients in coma or vegetative state, patients with Severe and Moderate TBI in recovery period. Subjects were stimulated with auditory stimuli containing important physiological sounds (coughing, vomiting), emotional sounds (laughing, crying), nature sounds (bird song, barking), unpleasant household sounds (nails scratching the glass), natural sounds (sea, rain, fire) and neutral sounds (white noise). The background encephalographic activity was registered during at least 7 minutes. EEG was recorded while using portable device "Entsefalan". Significant differences of power of the rhythmic activity registered during the presentation of different types of stimuli were analyzed using Mathlab and Statistica 6.0. Results showed that EEG-response to the emotional stimuli differed depending on consciousness level, stimuli type, severity of TBI. Most valuable changes in EEG spectrum power for a patient with TBI were found for unpleasant auditory stimulation. Responsiveness to the pleasant stimulation could be registered in later stages of coming out of coma than to unpleasant stimulation. Alpha-activity is reducing in patients with TBI: the alpha rhythm depression is most evident in the control group, less in group after moderate TBI, and even less in group after severe TBI. Patients in coma or vegetative state didn't show any response in rhythmic power in the frequency of alpha rhythm.

Quantification of the adult EEG background pattern

ObjectiveVisual interpretation of EEG is time-consuming and not always consistent between reviewers. Our objective is to improve this by introducing guidelines and algorithms to quantify various properties, focussing on the background pattern in adult EEGs. MethodsFive common properties were evaluated: (i) alpha rhythm frequency; (ii) reactivity; (iii) anterio–posterior gradients; (iv) asymmetries; and (v) diffuse slow-wave activity. A formal description was found for each together with a guideline and proposed quantitative algorithm. All five features were automatically extracted from routine EEG recordings. Modified time-frequency plots were calculated to summarize spectral and spatial characteristics. Visual analysis scores were obtained from diagnostic reports. ResultsAutomated feature extraction was applied to 384 routine EEGs. Inter-rater agreement was calculated between visual and quantitative analysis using Fleiss’ kappa: κ={(i)0.60;(ii)0.35;(iii)0.19;(iv)0.12;(v)0.76}. The method is further illustrated with three representative examples of automated reports. ConclusionsAutomated feature extraction of several background EEG properties seems feasible. Inter-rater agreement differed between various features, ranging from slight to substantial. This may be related to the nature of various guidelines and inconsistencies in visual interpretation. SignificanceFormal descriptions, standardized terminology, and quantitative analysis may improve inter-rater reliability in reporting of the EEG background pattern and contribute to more efficient and consistent interpretations.

Somatomotor mu rhythm amplitude correlates with rigidity during deep brain stimulation in Parkinsonian patients

ObjectiveParkinsonian patients have abnormal oscillatory activity within the basal ganglia-thalamocortical circuitry. Particularly, excessive beta band oscillations are thought to be associated with akinesia. We studied whether cortical spontaneous activity is modified by deep brain stimulation (DBS) in advanced Parkinson’s disease and if the modifications are related to the clinical symptoms. MethodsWe studied the effects of bilateral electrical stimulation of subthalamic nucleus (STN) on cortical spontaneous activity by magnetoencephalography (MEG) in 11 Parkinsonian patients. The artifacts produced by DBS were suppressed by tSSS algorithm. ResultsDuring DBS, UPDRS (Unified Parkinson’s Disease Rating Scale) rigidity scores correlated with 6–10Hz and 12–20Hz somatomotor source strengths when eyes were open. When DBS was off UPDRS action tremor scores correlated with pericentral 6–10Hz and 21–30Hz and occipital alpha source strengths when eyes open.Occipital alpha strength decreased during DBS when eyes closed. The peak frequency of occipital alpha rhythm correlated negatively with total UPDRS motor scores and with rigidity subscores, when eyes closed. ConclusionSTN DBS modulates brain oscillations both in alpha and beta bands and these oscillations reflect the clinical condition during DBS. SignificanceMEG combined with an appropriate artifact rejection method enables studies of DBS effects in Parkinson’s disease and presumably also in the other emerging DBS indications.