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Objective. Elaboration of objective quantitative criterion of electroencephalogram for estimation of the brain functional state in man. Маterials and methods. The background electroencephalograms analysis was conducted in 6 groups of the examined patients with various diagnosis (41 patients at all). Control group consisted of 7 patients, ageing 20 - 56 yrs (average age 35 yrs). Recording of EEG was conducted, using 16-channel electroencephalograph «NeuroCom standart» (KhАI - Меdika, Ukraine) in accordance to international system of recording «10-20». There were analyzed a quantity of meaningful interhemispheric asymmetries in accordance to power of summarized bioelectric signal in bilateral-synchronous points of the head in every group. The analysis time have constituted 1 min. Results. There was established, that the least meaningful difference in accordance to the bioelectrical signal power in bilateral-synchronous points of head may be considered in 1.4 times. Quantity of meaningful interhemispheric asymmetries in man may vary in large diapason - from 9 tо 25. Not all meaningful interhemispheric asymmetries in accordance to power of signals of separate rhythms are preserved while doing analysis of meaningful interhemispheric asymmetries in accordance to power of a summarized bioelectrical signal. Interhemispheric asymmetries in accordance to power of the summarized bioelectric signal in bilateral-synchronous points of the head may have more important informative meaning, than interhemispheric asymmetry in accordance to the signals power of separate rhythms. Conclusion. Quantity of meaningful interhemispheric asymmetries in accordance to power of signals of separate rhythms in healthy persons may vary from 16 tо 18. The interhemispheric asymmetries quantity reduction in accordance to power of the summarized bioelectric signal, comparing with quantity of interhemispheric asymmetries in accordance to power of signals of separate rhythms more than in 4 times, witnesses presence of the brain bioelectrical buffer system.

Electroencephalography (EEG) as a biomarker of neuromodulation by High Definition transcranial Direct Current Stimulation (HD-tDCS) offers promise as both techniques are deployable and can be integrated into a single head-gear. The present research addresses experimental design for separating focal EEG effect of HD-tDCS in the ‘4-cathode × 1-anode’ (4 × 1) montage over the left motor area (C3). We assessed change in offline EEG at the homologous central (C3, C4), and occipital (O1, O2) locations. Interhemispheric asymmetry was accessed for background EEG at standard frequency bands; and for the intermittent photic stimulation (IPS). EEG was compared post- vs pre-intervention in three HD-tDCS arms: Active (2 mA), Sham (ramp up/down at the start and end), and No-Stimulation (device was not powered), each intervention lasting 20 min. The asymmetric background EEG changes were only in the central areas with right-side amplitude spectra prevalence, most pronounced in the no-stimulation arm, where they depended on comparison time-points and were consistent with markers of transition between drowsiness and vigilance – bilateral decrease in the delta and asymmetric central increase in the alpha and beta1 bands. For the active arm, similar but less pronounced changes occurred in the alpha band. In contrast, responses to IPS developed similar asymmetric amplitude increase at four harmonics of the IPS of 3 Hz only in the active arm, against a background of a brain-wide symmetric increase in both active and sham arms. Our protocols and analyses suggest methodological caveats for how EEG of tDCS studies could be conducted to isolate putative brain polarization outcomes.

Functional hemispheric asymmetry was evidenced in many species during sleep. Dogs seem to show hemispheric asymmetry during wakefulness; however, their asymmetric neural activity during sleep was not yet explored. The present study investigated interhemispheric asymmetry in family dogs using non-invasive polysomnography. EEG recordings during 3-h-long afternoon naps were carried out (N = 19) on two occasions at the same location. Hemispheric asymmetry was assessed during NREM sleep, using bilateral EEG channels. To include periods with high homeostatic sleep pressure and to reduce the variance of the time spent in NREM sleep between dogs, the first two sleep cycles were analysed. Left hemispheric predominance of slow frequency range was detected in the first sleep cycle of sleep recording 1, compared to the baseline level of zero asymmetry as well as to the first sleep cycle of sleep recording 2. Regarding the strength of hemispheric asymmetry, we found greater absolute hemispheric asymmetry in the second sleep cycle of sleep recording 1 and 2 in the frequency ranges of alpha, sigma and beta, compared to the first sleep cycle. Differences between sleep recordings and consecutive sleep cycles might be indicative of adaptation-like processes, but do not closely resemble the results described in humans.

Background: Interhemispheric asymmetry caused by brain lesions is an adverse factor in the recovery of patients with neurological deficits. Repetitive transcranial magnetic stimulation (rTMS) has been shown to modulate cortical oscillation and proposed as an approach to rebalance the symmetry, which has not been documented well. Objective: In this study, we investigated the influence of repetitive transcranial magnetic stimulation (rTMS) on EEG power in patients with unilateral brain lesions by simultaneously stimulating both brain hemispheres and to elucidate asymmetrical changes in rTMS-induced neurophysiological activity. Methods: Fourteen patients with unilateral brain lesions were treated with one active and one sham session of 10 Hz rTMS over the vertex (Cz position). Resting-state EEGs were recorded before and immediately after rTMS. The brain symmetry index (BSI), calculated from a fast Fourier transform, was employed to quantify the power asymmetry in both hemispheres and paired channels over the entire range and five frequency bands (delta, theta, alpha, beta and gamma bands). Results: Comparison between active and sham sessions demonstrated rTMS-induced EEG after-effects. rTMS in the active session significantly reduced the BSI in patients with unilateral brain lesions over the entire frequency range (t = 2.767, P = 0.016). Among the five frequency bands, rTMS only induced a noticeable decrease in the BSI in the delta band (t = 2.254, P = 0.042). Furthermore, analysis of different brain regions showed that significant changes in the BSI of the alpha band were only demonstrated in the posterior parietal lobe. In addition, EEG topographic mapping showed a decreased power of delta oscillations in the ipsilesional hemisphere, whereas distinct cortical oscillations were observed in the alpha band around the parietal-occipital lobe in the contralesional hemisphere. Conclusions: When both brain hemispheres were simultaneously activated, rTMS decreased interhemispheric asymmetry primarily via reducing the delta band in the lesioned hemisphere.

Background The purpose of this review is to provide a comprehensive overview of the findings of clinical electrophysiology studies aimed to investigate changes in information processing of migraine with aura patients. Main body Abnormalities in alpha rhythm power and symmetry, the presence of slowing, and increased information flow in a wide range of frequency bands often characterize the spontaneous EEG activity of MA. Higher grand-average cortical response amplitudes, an increased interhemispheric response asymmetry, and lack of amplitude habituation were less consistently demonstrated in response to any kind of sensory stimulation in MA patients. Studies with single-pulse and repetitive transcranial magnetic stimulation (TMS) have reported abnormal cortical responsivity manifesting as greater motor evoked potential (MEP) amplitude, lower threshold for phosphenes production, and paradoxical effects in response to both depressing or enhancing repetitive TMS methodologies. Studies of the trigeminal system in MA are sparse and the few available showed lack of blink reflex habituation and abnormal findings on SFEMG reflecting subclinical, probably inherited, dysfunctions of neuromuscular transmission. The limited studies that were able to investigate patients during the aura revealed suppression of evoked potentials, desynchronization in extrastriate areas and in the temporal lobe, and large variations in direct current potentials with magnetoelectroencephalography. Contrary to what has been observed in the most common forms of migraine, patients with familial hemiplegic migraine show greater habituation in response to visual and trigeminal stimuli, as well as a higher motor threshold and a lower MEP amplitude than healthy subjects. Conclusion Since most of the electrophysiological abnormalities mentioned above were more frequently present and had a greater amplitude in migraine with aura than in migraine without aura, neurophysiological techniques have been shown to be of great help in the search for the pathophysiological basis of migraine aura.

Коробова Светлана Юрьевна, научный сотрудник, лаборатория психологии и психофизиологии стрессоустойчивости и креативности, Южно-Уральский государственный университет (Россия, 454080, Челябинск, проспект Ленина, 76), k.svetlana-1991@mail.ru, ORCID 0000-0002-8633-7231 Грязева-Добшинская Вера Геннадьевна, доктор психологических наук, профессор, заведующий лабораторией психологии и психофизиологии стрессоустойчивости и креативности, Южно-Уральский государственный университет (Россия, 454080, Челябинск, проспект Ленина, 76), vdobshinya@mail.ru, ORCID 0000-0002-9986-4073 Чипеева Надежда Александровна, научный сотрудник, лаборатория психологии и психофизиологии стрессоустойчивости и креативности, Южно-Уральский государственный университет (Россия, 454080, Челябинск, проспект Ленина, 76), n.chipeeva@gmail.com, ORCID 0000-0003-0845-3138 S.Yu. Korobova, k.svetlana-1991@mail.ru, ORCID 0000-0002-8633-7231 V.G. Gryazeva-Dobshinskaya, vdobshinya@mail.ru, ORCID 0000-0002-9986-4073 N.A. Chipeeva, n.chipeeva@gmail.com, ORCID 0000-0003-0845-3138 South Ural State University (76 Lenin Avenue, Chelyabinsk, 454080, Russian Federation) Рассматриваются взаимосвязи электродермальной активности с двух сторон тела с активацией областей головного мозга и соотношение асимметрии электродермальной активности с асимметрией полушарий головного мозга у практически здоровых студентов. Цель. Выявить особенности взаимосвязей двусторонней электродермальной активности с показателями спектральной мощности ЭЭГ, а также сопоставить асимметрию электродермальной активности с асимметрией полушарий головного мозга. Материалы и методы. Выборка студентов разных профилей обучения составила 30 человек (18–25 лет), из них 18 юношей. Электродермальная активность оценивалась методом неспецифической эндодермальной реакции кожного потенциала по Тарханову с ладоней двух рук на аппаратурно-программном комплексе «Активациометр АЦ-9К» Ю.А. Цагарелли. Регистрация ЭЭГ производилась с помощью 64-канального электроэнцефалографа BP-100-2110-Система «actiCHamp-64», с использованием пакета Brain Products PyCorder. Для выявления взаимосвязей электродермальной активности с показателями спектральной мощности ЭЭГ, а также при сопоставлении асимметрии электродермальной активности и асимметрии полушарий головного мозга использовался коэффициент ранговой корреляции rs-Спирмена. Результаты. Выявлена специфика взаимосвязей электродермальной активности, регистрируемой как традиционно – с левой ладони, так и с правой ладони, а также их суммарного показателя с активацией зон головного мозга во всех диапазонах частот. Большинство взаимосвязей электродермальной активности выявлено с активацией левого полушария. Асимметрия электродермальной активности соотносится с асимметрией областей головного мозга, которые функционально связывают с электродермальной активностью. The paper considers the correlation between two-sided electrodermal activity and brain activation, as well as the correlation between the asymmetry of electrodermal activity and the asymmetry of the cerebral hemispheres. Aim. The paper aims to identify the correlation between electrodermal activity and EEG spectrum power so to compare the asymmetry of electrodermal activity and the asymmetry of the cerebral hemispheres. Materials and methods. The sample consisted of 30 people aged from 18 to 25 years (18 males and 12 females). Electrodermal activity was assessed by the method of nonspecific endodermal response (by Tarkhanov) with the help of the Activatsiometr AC-9K system proposed by Yu.A. Tsagarelli. EEG recording was performed using a 64-channel electroencephalograph (actiCHamp-64) and the Brain Products PyCorder package. Results. The features of the correlation between electrodermal activity and brain activation were found in all frequency bands. Most of the correlations were associated with the left hemisphere. The asymmetry of electrodermal activity correlates with the asymmetry of brain areas associated with electrodermal activity.

During the 520-d imitation of isolation and confinementin a long-duration exploration mission, the neuroufunctional state of 6 crewmembers was studied by synchronous registration of cerebral electrical (EEG) and energy (permanent potential level (PPL)) activities of the brain. Two baseline investigations predicted high adaptability of all crew members and low probability of depletion of the adaptation reserve in the experiment. During isolation, dynamics of neurofunctional correlates of the cerebral activity was generally proportionate to the factors the crewmembers were affected by. Events epochal to the crew gave rise to physiological reactions both of the metabolic and electrical activity of the brain. On week 54, crew physiological adaptation to the experimental environment was manifested by decreases in PPL without interhemispheric asymmetry and absolute a-power. All through the experiment none of the crew members showed signs of a distinct stress-reaction (a-activity asymmetry with a significant PPL decrease) supporting our prediction of low probability of adaptation reserve depletion in participants in the 520-day isolation and confinement study.

This paper analyzes changes during aging in the electroencephalographic (EEG) synchronization between different areas of the cerebral cortex in healthy elderly subjects under visual stimulation. Two groups were selected: one (A) of 10 adults aged 50-65 years and another (B) of 15 subjects aged 66-80 years. EEG recordings of 16 "monopolar" channels were carried out (digitized at 256 Hz), all referenced to the mean and following the standard 10-20 system, and were performed at rest with eyes closed under visual stimulation. From an index (L) of nonlinear generalized synchronization, the average cortical synchronization (ACS) of each channel with the rest and the corresponding average asymmetry in the synchronization (ACM) was estimated. Changes with age (A vs. B) in cortical synchronization and in average interhemispheric asymmetry for all cortical areas were estimated via a repeated measures MANOVA. The results show that under visual stimulation, the SCM decreases with age for most channels (p < 0.01) except for the frontals. The channels that showed asymmetry in the synchronization (p < 0.01) were the frontals F3, F4 y Fp2, the parietal P3 and the temporal T5, in all of them a significant reduction in asymmetry with age (p < 0.01) was observed.

Вступ. Особливий інтерес для лікування різних неврологічних розладів, зокрема дитячого церебрального паралічу (ДЦП), викликає такий терапевтичний підхід, як мікрополяризація. Мікрополяризація – це неінвазивний і безпечний лікувальний метод, що дозволяє змінювати функціональний стан різних ланок ЦНС під дією малого постійного струму.Мета – визначити за допомогою електроенцефалографії терапевтичну ефективність додавання методу мікрополяризації у комплекс лікувально-профілактичних засобів дітям хворим на ДЦП.Матеріали та методи. У ході дослідження було обстежено та комплексно проліковано 33 хворих з різними формами ДЦП. До порівняльної групи, яким проводили базисні лікувально-реабілітаційні заходи, увійшло 12 дітей, до основної – 21 дитина, яким на фоні базисної терапії додатково проводили курс мікрополяризації. Транскраніальна мікрополяризація виконувалася згідно з розробленими індивідуальними схемами лікування залежно від локалізації патології. За допомогою ЕЕГ оцінювали біоелектричну активність головного мозку в динаміці двічі – до початку лікування та через 3 місяці після закінчення терапевтичного курсу.Результати. Аналіз електроенцефалограм дітей із ДЦП до лікування свідчив про порушення біоелектричної активності мозку різного ступеня виразності. Після лікування у межах загальної картини формування вікових патернів ЕЕГ спостерігалась спрямована позитивна динаміка фонової біоелектричної активності мозку у 76,2% пацієнтів основної групи, порівняно із 25,0% дітей у групі порівняння. Загальні зміни стосувались стабілізації вікових прекурсорів центрального і альфа-ритмів і спостерігалися тенденції до зменшення структурної дезорганізації і дифузного сповільнення ЕЕГ при відсутності збільшення пароксизмальної активності та міжпівкульової асиметрії.Висновки. Отримані дані свідчать про те, що додавання методу мікрополяризації у комплексне лікування хворих на ДЦП підвищує ефективність лікування, а також може позитивно впливати на клінічний перебіг захворювання.

A trend in EEG interhemispheric asymmetry was studied in patients with endogenous depressions in morning and evening hours. In the morning, the spectral power of alpha rhythm particularly in the occipital cortical regions, proved to be higher than that in the evening. In the morning, the interhemispheric differences in the power of occipital alpha rhythm were leveled off while in the evening there was normalization of interhemispheric balance with the higher power of alpha rhythm in the right occipital region. Analysis of the mean coherence (mean Coh) of alpha rhythm in individual cortical regions revealed that the patients with endogenous depression had higher readings mainly in the parietal and central regions of both hemispheres and in the right temporal regions in the morning than in the evening. The occipital and posttemporal regions showed an inverse trend in the mean Coh - it was lower in the morning than in the evening.

O objetivo do presente estudo foi avaliar os efeitos da estimulação elétrica funcional na assimetria cortical inter-hemisférica. Para tal, simultaneamente ao registro da atividade eletroencefalográfica, realizou-se eletroestimulação no antebraço direito para estimulação da extensão do indicador. A amostra consistiu de 45 sujeitos randomizados em 3 grupos de 15 sujeitos cada: grupo controle (submetido a 24 blocos de estimulação com intensidade de corrente zero), grupo 1 (24 blocos) e grupo 2 (36 blocos). A assimetria entre os pares de eletrodos F3-F4, C3-C4 e P3-P4 foi analisada ao longo dos grupos através de uma Anova. Os resultados apontaram para uma interação grupo x eletrodo e uma tendência de diminuição da assimetria inter-hemisférica após a eletroestimulação.

When dolphins sleep, their electroencephalographic activity may change in only one cerebral hemisphere; i.e., the left and right brain hemispheres can take turns sleeping. We demonstrate that the bispectral index (BIS) monitor can detect interhemispheric asymmetry in the dolphin species Tursiops truncatus. Using two BIS sensors placed simultaneously over each side of the dolphin's head, we often, but not always, found significant differences between the two BIS values (e.g., left side 60 and right side 90) in non-medicated animals and in animals given propofol, atropine, and/or diazepam. Observations were each made over a period of approximately 3 h on dolphins resting out of the water. Unihemispheric effects may be inducible pharmacologically in dolphins. The dolphin, with its human-sized brain, may provide an animal model for study of unihemispheric effects in humans.

Pregnant women were examined during I, II, and III trimesters in order to detect EEG correlations of gestation dominant in health and threatened abortion. Single uncomplicated pregnancy was characterized by predominant activation in the central and temporal areas contralateral to the location of the placenta. Threatened abortion was associated with inversion of interhemispheric asymmetry of activation with respect to the placenta location.

Transient visual evoked potentials (VEP) were recorded simultaneously from 16 electrodes evenly placed over posterior scalp locations covering the occipital, posterior parietal and temporal areas. Interhemispheric amplitude difference of the N70 deflection was established across 6 homologous lateral electrode pairs in 15 normal controls and 32 patients with chiasmatic or retrochiasmatic cerebral lesions. Twenty-three of these had known homonymous or bitemporal field defects while 9 had normal fields on routine perimetry. Significant interhemispheric asymmetry of any single electrode pair occurred in 55% of the 32 patients with known pathology, while the cumulative yield of all electrode pairs was over 80 percent. The diagnostic yield of individual electrode pairs was significantly different: the electrode pair placed over the temporo-parietal junction detected the highest number of abnormalities. The cumulative abnormality taken over all lateral electrode pairs could be described with a curve well fitted with a probability summation function. It is inferred that the contribution of several independent generator sources is reflected in the N70 of the pattern onset VEP. The results suggest that multichannel recording of the interhemispheric amplitude distribution of the N70 of the onset VEP is useful for the evaluation of paracentral visual field defects.

Aquatic mammals (i.e., Cetaceans, eared seals and manatees) and birds show interhemispheric asymmetries (IA) in slow-wave sleep-related electroencephalographic (EEG) activity, suggesting that the depth of sleep differs between hemispheres. In birds, an association between unilateral eye closure and IA has been reported in five species from three orders (i.e., Galliformes, Charadriiformes, and Anseriformes). Moreover, unilateral eye closure has been observed during behaviorally defined sleep in 29 species from 13 avian orders, suggesting that birds in general display IA during sleep. Despite the apparent prevalence of unilateral eye closure and IA in birds, previous work did not detect IA in the pigeon, thereby challenging the conclusion that this is a general feature of birds. Using digital period amplitude analysis, an objective method for quantifying EEG power (a measure of wave amplitude) across different frequencies, we demonstrate that pigeons do, in fact, display an association between unilateral eye closure and IA. For a given hemisphere, standardized 2–4 Hz EEG power was greater when the contralateral eye was closed when compared to open. We also found that pigeons used the open eye during IA to monitor their environment. In addition, individual pigeons showed a bias for keeping one eye open more than the other. The direction (left vs. right) of this bias differed across birds, and appeared to be influenced by the structure of the surrounding environment. Finally, with the addition of pigeons (order Columbiformes), IA associated with unilateral eye closure has been recorded in four avian orders, suggesting that this form of sleep is widespread in birds.

This article generalizes the results of many years’ studies of the EEG of patients with tumorous lesions in the diencephalic, brainstem, and limbic structures, which fulfill the regulatory function in ensuring integral brain activity. The specific features of the inclusion of individual structures under investigation in the organization of the intra- and interhemispheric relations of cortical biopotentials were demonstrated against the background of diffuse changes in the biopotentials that reflect the systemic character of neurodynamic reorganizations when the regulatory brain structures are involved in the pathological process. This study expands the idea of the predominant functional connection of the diencephalic structures with the right hemisphere and brainstem structures with the left one with determination of the regional specific features of changes in the intrahemispheric EEG coherences. The distinguishing features of intercentral relations when the limbic structures are involved in the pathological process show similarity with the neurodynamic reorganizations in patients with lesions in both diencephalic and (even more so) brainstem structures. Universal elements were detected in the formation of integral adaptive reactions of the brain with lesions in its regulatory structures, which reflects their close functional interaction and makes it possible to consider them the individual links of an integral regulatory system. The study revealed reciprocal changes in various forms of electrical activity, which reflects reciprocation of interaction of individual regulatory structures. This is one of the EEG equivalents of the formation of adaptive-compensatory cerebral reactions. The specificity of influence of the studied regulatory structures are clearly seen in situations of their morphofunctional isolation observed during cerebral coma. In these conditions, when the cortex is functionally inactive, the authors demonstrated the dynamic character of changes in interhemispheric asymmetry, which reflects the dominance of individual links of the regulatory system playing the role of supreme regulator of life support of the body in critical states.

Five healthy right-handed subjects learned to control hemispheric asymmetry with biofeedback of the amplitude difference of slow cortical potentials between the left and the right precentral areas. Six training sessions were conducted with subject I, 12 sessions with subjects II and III, and 14 sessions, with subjects IV and V. Performance of four out of five subjects improved continuously as a function of sessions. Towards the end of training, these subjects demonstrated highly significant differentiation between conditions where right versus left precentral negativity was required. In subject V, no improvement was observed after 14 training sessions. The data indicate that most subjects can learn to self-generate fast electroencephalograph (EEG) differences between the left and the right sensorimotor cortical regions.

En este trabajo analizamos los cambios durante el envejecimiento en la sincronización electroencefalográfica (EEG) entre distintas zonas de la corteza cerebral en sujetos mayores sanos bajo estimulación visual. Se seleccionaron dos grupos: uno (A) de 10 adultos de edades entre 50-65 años y otro (B) de 15 sujetos entre 66-80 años. Se realizaron registros de 16 canales EEG monopolares (digitalizados a 256 Hz) referenciados a la media siguiendo el sistema estándar 10-20, registrados en condiciones de reposo con ojos cerrados bajo estimulación visual. A partir de un índice (L) de sincronización nolineal generalizada se estimó la sincronización cortical media (SCM) de cada canal con el resto y la correspondiente asimetría interhemisférica media en la sincronización (ACM). Los cambios con la edad (A vs. B) en la sincronización y en la asimetría media para el conjunto de canales/áreas corticales se estimaron a través de un MANOVA de medidas repetidas. Los resultados muestran que, bajo estimulación visual, la SCM decrece con la edad para la mayoría de los canales (p < 0.01) a excepción de los frontales. Los canales que presentaron asimetría interhemisférica en la sincronización (p < 0.01) fueron los frontales F3, Fp2 y F4, el parietal P3 y el temporal T5, en los que se observó una importante disminución de la asimetría con la edad (p < 0.01).

Thirty-one elderly depressive patients were evaluated with topographic, quantitative EEG using relative measures, absolute measures, and computations of interhemispheric asymmetry and interhemispheric coherence in four frequency bands: delta, theta, alpha and beta. Patients were found to have lower than normal delta, higher than normal theta, higher than normal alpha and lower than normal beta values. EEG values were greater over the left than the right hemisphere in theta, alpha and beta bands. Lower than normal anterior interhemispheric coherence was found in all four frequency bands.

The authors determined the individual profile of functional interhemispheric asymmetry (IPFIA) in 70 patients (28 men and 42 women) with Parkinson's disease (PD), by using the examination protocol comprising 48 assignments, its association with clinical asymmetry and effect on electroencephalography (ECG) readings. Right-sided PD onset was significantly more frequently observed in patients with a right IPFIA than in those with mixed and left IPFIAs (p

Sleep spindles, as defined in the international electroencephalography (EEG) glossary, are distinguished from spindle bursts seen in the EEGs of premature infants. Classical sleep spindles do not occur in prematures. They first appear clearly in the EEG during slow wave sleep from the 4th week postterm (44 weeks conceptional age) and are normally present in all infants' EEGs by 9 weeks postterm. During the first year of life they may be of high voltage relative to their appearance in older children and adults and are commonly characterized by variable degrees of interhemispheric asymmetry and asynchrony. Individual differences are great. Some features of clinical significance are discussed.

1. The motor dominant created by single polarization can last for a long time after disconnecting the direct current within the experiment and recovers during the next several days under the effect of testing stimuli. 2. Recovery of the structure of the intercentral relations of electrical activity of the brain characteristic for the dominant state corresponds to recovery of the dominant. 3. Interhemispheric asymmetry of coherent relations of electrical activity characteristic for the dominant state recovers considerably earlier than manifestation of the motor “dominant” reaction.

EEG recordings were obtained from 10 normal and 10 aphasic adults while they participated in behavioral tasks and a no performance condition. Interhemispheric asymmetry and average activity at 5 to 15 Hz in each hemisphere were compared between groups and among tasks. Asymmetry during behavioral tasks did not differ significantly between groups or among tasks, however, aphasic patients showed a significant decrease in average activity at 5 to 15 Hz on the behavioral tasks compared with the level for a no performance condition. Test-retest reliability was poor for asymmetry but acceptable for average activity at 5 to 15 Hz. Finally, asymmetry was significantly related with severity of aphasia.

Magnetic auditory evoked fields (MAEFs) were recorded from the right (11 subjects) and the left (7 subjects) hemisphere following 128 click stimuli delivered to contralateral, ipsilateral and both (bilateral) ears. Right hemisphere MAEFs were of higher amplitude following contralateral, compared to ipsilateral, stimulation in 9 of 11 subjects; mean contralateral response amplitude was 135 ± 33% (S.D.) of ipsilateral response amplitude. Left hemisphere MAEFs were of higher amplitude following contralateral stimulation in 7 of 7 subjects; mean contralateral response amplitude was 145 ± 44% of ipsilateral response amplitude. These observations are compatible with evidence that a majority of centripetal auditory input is crossed, and/or that contralateral auditory stimulation activates a larger area of cortex than does ipsilateral stimulation.

Monopolar recordings of the EEG during sleep from each occipital area in normal volunteers indicated a consistent prevalence of spindles over the right hemisphere and more pronounced slow wave activity over the left. Asymmetry in the slow wave activity was confirmed by an analysis of the secondary components of the visually evoked potentials. The data indicated that the hemisphere generally considered to be “subdominant” during the awake state is subject to less intense non-REM sleep, suggesting a reversal in the “dominance” of hemispheres in sleep.

Purpose Recently, a novel multi-model monitor has been available, which integrates real-time signals of transcranial Doppler (TCD) and video-EEG (vEEG) into one workstation. We sought to test the feasibility of this device in detecting neurovascular coupling in patients with epilepsy. Method Cerebral blood flow velocity (CBFV) of bilateral middle cerebral arteries and vEEG during seizure episodes were recorded simultaneously in 12 patients (age 17–58 years) with partial epilepsies. The correlations between vEEG and CBFV findings were analyzed. Results Eleven seizure episodes were detected in 5 patients. Of them, bilateral CBFV increase with interhemispheric asymmetry was observed in 4 seizure episodes of 3 patients. EEG abnormalities preceded CBFV increase by 1–3s at the onset of a seizure. In a patient with bilateral middle cerebral artery stenosis, no apparent CBFV changes were detected during 2 of 3 seizure episodes. Another patient with previous frontal hemorrhage displayed CBFV increase without interhemispheric asymmetry during 4 seizure episodes. Conclusion It is feasible to evaluate neurovascular coupling with good temporal correlation in patients with frequent seizure episodes by real-time TCD-vEEG monitoring.

Ten out of eleven Wistar rats displayed a reliable interhemispheric asymmetry of the secondary slow negative wave (SNW) of the visual evoked potential. A more synchronized EEG was observed on the side of facilitated SNW. The analysis of rotation directionality in the rotometer of these rats after IP (+)-amphetamine administration (1.25 mg/kg) showed that rats reliably rotated towards the side with a more facilitated SNW. It is believed that an imbalance of nigrostriatal DA content underlies the interhemispheric asymmetry of EEG and evoked potentials.