Synchronous Discharges Research Articles

Disrupted auditory nerve activity limits peripheral but not central temporal acuity

Auditory neuropathy affects synaptic encoding or neural conduction of signals in the cochlea or the auditory nerve. Subjects with auditory neuropathy poorly recognize speech in noise which correlates with poor temporal processing. The integrity of temporal processes in the auditory system can be assessed with detection of just-noticeable differences in gap between sounds. Disorder in the auditory periphery appears to alter the precise timing or latency of synchronous neural discharges important for temporal coding. However, the relative contribution of auditory nerve activities to central temporal processing is unknown. Auditory neuropathy produced significantly worse than normal gap detection within a frequency but normal gap detection between different frequencies. No correlation between same- and different-frequency gap detection supports two temporal processes: a peripheral mechanism dependent on overlapping nerve fibers mediating same-frequency gaps and a central mechanism dependent on cross-correlated activity of non-overlapping fibers mediating different-frequency gaps. The fast, peripheral mechanism enables temporal acuity on the order of milliseconds and is likely limited by neural synchrony, the amount of total nerve activity, or both, whereas the sluggish, central mechanism is likely limited by switching time between perceptual channels on the order of a hundred milliseconds. The results demonstrate auditory nerve activities limit peripheral but not central temporal acuity.

Optogenetic activation of VGLUT2-expressing excitatory neurons blocks epileptic seizure-like activity in the mouse entorhinal cortex

We investigated whether an anti-epileptic effect is obtained by selectively activating excitatory neurons expressing ChR2 under the promoter for the synaptic vesicular glutamate transporter 2 (VGLUT2). VGLUT2-expressing cells were optically stimulated while local field potential and whole-cell patch-clamp recordings were performed in mouse entorhinal cortical slices perfused with the proconvulsive compound 4-aminopyridine (4-AP). In control conditions, blue light flashes directly depolarized the majority of putative glutamatergic cells, which in turn synaptically excited GABAergic interneurons. During bath perfusion with 4-AP, photostimuli triggered a fast EPSP-IPSP sequence which was often followed by tonic-clonic seizure-like activity closely resembling spontaneous ictal discharges. The GABAA-receptor antagonist gabazine blocked the progression of both light-induced and spontaneous seizures. Surprisingly, prolonged photostimuli delivered during ongoing seizures caused a robust interruption of synchronous discharges. Such break was correlated with a membrane potential depolarization block in principal cells, while putative GABAergic interneurons changed their firing activity from a burst-like to an irregular single-spike pattern. These data suggest that photostimulation of glutamatergic neurons triggers seizure-like activity only in the presence of an intact GABAergic transmission and that selectively activating the same glutamatergic cells robustly interrupts ongoing seizures by inducing a strong depolarization block, resulting in the disruption of paroxysmal burst-like firing.

A pulsed generator for synchronous discharges of high-energy plasma synthetic jet actuators

Plasma synthetic jet (PSJ) has a wide application prospect in flow separation suppression and boundary layer control. Comparing with traditional control methods, synchronous discharges of PSJ with high repetition frequency and high energy could achieve a better flow control effect because it can meet multi-angle, wide-range and long-time flow control requirements. In this paper, a microsecond-pulse power supply for synchronous discharges of three plasma synthetic jet actuators (PSJA) is developed. Parameters of output pulses are as follows: the maximum voltage pulse is 10 kV, the pulse repetition rate is 1000 Hz and the full width is 15 μs. The generator can withstand a discharge current with an amplitude of 320 A and a discharge energy of 150 mJ. The electrical characteristics of the synchronous discharges of PSJAs including the voltage-current waveforms, discharge images and Schlieren images are investigated. The experimental result shows that the microsecond-pulse generator could sustain three discharge channels in PSJAs when the output voltage is 10 kV. These discharge channels have preferable performance in synchronicity when the repetition frequency is 1000 Hz. Furthermore, the Schlieren images show that the power supply can sustain three PSJAs with a maximum jet velocity of up to 150 m/s.

Coupling multielectrode array recordings with silver labeling of recording sites to study cervical spinal network connectivity.

Midcervical spinal interneurons form a complex and diffuse network and may be involved in modulating phrenic motor output. The intent of the current work was to enable a better understanding of midcervical "network-level" connectivity by pairing the neurophysiological multielectrode array (MEA) data with histological verification of the recording locations. We first developed a method to deliver 100-nA currents to electroplate silver onto and subsequently deposit silver from electrode tips after obtaining midcervical (C3-C5) recordings using an MEA in anesthetized and ventilated adult rats. Spinal tissue was then fixed, harvested, and histologically processed to "develop" the deposited silver. Histological studies verified that the silver deposition method discretely labeled (50-μm resolution) spinal recording locations between laminae IV and X in cervical segments C3-C5. Using correlative techniques, we next tested the hypothesis that midcervical neuronal discharge patterns are temporally linked. Cross-correlation histograms produced few positive peaks (5.3%) in the range of 0-0.4 ms, but 21.4% of neuronal pairs had correlogram peaks with a lag of ≥0.6 ms. These results are consistent with synchronous discharge involving mono- and polysynaptic connections among midcervical neurons. We conclude that there is a high degree of synaptic connectivity in the midcervical spinal cord and that the silver-labeling method can reliably mark metal electrode recording sites and "map" interneuron populations, thereby providing a low-cost and effective tool for use in MEA experiments. We suggest that this method will be useful for further exploration of midcervical network connectivity.NEW & NOTEWORTHY We describe a method that reliably identifies the locations of multielectrode array (MEA) recording sites while preserving the surrounding tissue for immunohistochemistry. To our knowledge, this is the first cost-effective method to identify the anatomic locations of neuronal ensembles recorded with a MEA during acute preparations without the requirement of specialized array electrodes. In addition, evaluation of activity recorded from silver-labeled sites revealed a previously unappreciated degree of connectivity between midcervical interneurons.

SB-334867, an orexin receptor 1 antagonist, decreased seizure and anxiety in pentylenetetrazol-kindled rats.

Convulsive seizures are due to abnormal synchronous and repetitive neuronal discharges in the central nervous system (CNS). Finding new therapeutics to overcome the side effects of the current drug therapies and to increase their effectiveness is ongoing. Orexin-A and orexin-B are brain neuropeptides originating from postero-lateral hypothalamic neurons. Studies show that orexins, through activation of OX1 and OX2 receptors, have excitatory effects in the CNS. Accordingly, this study was designed to evaluate the effect of OX1 receptor antagonist (SB-334867) on seizure- and anxiety-related behaviors of pentylenetetrazol (PTZ)-kindled rats. Kindling was induced by repeated intraperitoneal (IP) injections of PTZ (32 mg/kg) with two-day intervals for 24 days in male Wistar rats. Three groups received intracerebroventricular (ICV) injections of SB-334867 (2.5, 5, and 10 μg/rat) before PTZ injections. Two control groups received vehicle (2 μL/rat, ICV) and valproate (26 μg/rat, ICV) before PTZ injections. An extra group of control animals received saline both ICV and IP. Seizure-related behaviors were monitored for 30 min following PTZ administration. The anxiety-like behaviors were also assessed using elevated plus-maze in the first and last days of the study. The results revealed that ICV injection of SB-334867, mainly at the dose of 10 μg/rat, decreased the median of seizure stages, prolonged the latency and reduced the duration of different seizure stages, and reversed the PTZ-induced anxiety-like behaviors. Based on the presented results, it is suggested that pharmacological blockade of the OX1 receptor is a potential target in the treatment of seizure and concomitant anxiety disorders.

A New Approach of Modified Submerged Patch Clamp Recording Reveals Interneuronal Dynamics during Epileptiform Oscillations.

Highlights Simultaneous epileptiform LFPs and single-cell activity can be recorded in the membrane chamber.Interneuron firing can be linked to epileptiform high frequency activity.Fast ripples, unique to chronic epilepsy, can be modeled in ex vivo tissue from TeNT-treated rats.Traditionally, visually-guided patch clamp in brain slices using submerged recording conditions has been required to characterize the activity of individual neurons. However, due to limited oxygen availability, submerged conditions truncate fast network oscillations including epileptiform activity. Thus, it is technically challenging to study the contribution of individual identified neurons to fast network activity. The membrane chamber is a submerged-style recording chamber, modified to enhance oxygen supply to the slice, which we use to demonstrate the ability to record single-cell activity during in vitro epilepsy. We elicited epileptiform activity using 9 mM potassium and simultaneously recorded from fluorescently labeled interneurons. Epileptiform discharges were more reliable than in standard submerged conditions. During these synchronous discharges interneuron firing frequency increased and action potential amplitude progressively decreased. The firing of 15 interneurons was significantly correlated with epileptiform high frequency activity (HFA; ~100–500 Hz) cycles. We also recorded epileptiform activity in tissue prepared from chronically epileptic rats, treated with intrahippocampal tetanus neurotoxin. Four of these slices generated fast ripple activity, unique to chronic epilepsy. We showed the membrane chamber is a promising new in vitro environment facilitating patch clamp recordings in acute epilepsy models. Further, we showed that chronic epilepsy can be better modeled using ex vivo brain slices. These findings demonstrate that the membrane chamber facilitates previously challenging investigations into the neuronal correlates of epileptiform activity in vitro.

Recent Developments of Hydrazide/Hydrazone Derivatives and Their Analogs as Anticonvulsant Agents in Animal Models.

Preclinical Research Epilepsy is a chronic devastating neurological disorder characterized by synchronous interictal discharges. Treatment with antiepileptic drugs (AEDs) can alleviate spontaneous seizure activity without preventing the progression and development of epileptogenesis. Current design and development of new AEDs and strategies for the prevention of epilepsy is focused mainly on attenuating uncontrolled seizures, severe side effects and toxicity in chronic drug therapy. It has thus become necessary to discover new chemical pharmacophores with a broad spectrum of activity and less neurotoxicity. Hydrazide/hydrazone derivatives that possess a -CO-NHN=CH- group constitute an important class of compounds for drug development. This review highlights the specific characteristics of various hydrazide/hydrazone derivatives and structurally related semicarbazones, semicarbazides and Schiff base compounds and their anticonvulsant activities. It is focused on the influence of differently substituted pharmacophores developed through SAR studies and testing their activity against different pharmcological targets. Drug Dev Res 77 : 379-392, 2016. © 2016 Wiley Periodicals, Inc.

Burst firing of single neurons in the human medial temporal lobe changes before epileptic seizures.

To better understand the mechanisms that lead to the sudden and unexpected occurrence of seizures, with the neuronal correlate being abnormally synchronous discharges that disrupt neuronal function. To address this problem, we recorded single neuron activity in epilepsy patients during the transition to seizures to uncover specific changes of neuronal firing patterns. We focused particularly on neurons repeatedly firing discrete groups of high-frequency action potentials (so called bursters) that have been associated with ictogenesis. We analyzed a total of 459 single neurons and used the mean autocorrelation time as a quantitative measure of burstiness. To unravel the intricate roles of excitation and inhibition, we also examined differential contributions from putative principal cells and interneurons. During interictal recordings, burstiness was significantly higher in the seizure onset hemisphere, an effect found only for principal cells, but not for interneurons, and which disappeared before seizures. These findings deviate from conventional views of ictogenesis that propose slowly-increasing aggregates of bursting neurons which give rise to seizures once they reach a critical mass. Instead our results are in line with recent hypotheses that bursting may represent a protective mechanism by preventing direct transmission of postsynaptic high-frequency oscillations.

Modulation of 4-aminopyridine-induced neuronal activity and local pO(2)in rat hippocampal slices by changing the flow rate of the superfusion medium.

The brain slice preparation is the most frequently used tool for testing of pharmacological agents on the neuronal excitability. However in the absence of blood circulation in vitro, the tissue oxygenation strongly depends on the experimental conditions. It is well established that both hypoxia as well as hyperoxia can modulate the neuronal network activity. Thereby changes in tissue oxygen level during experiment may affect the final result. In the present study we investigated the effect of oxygenation on seizure susceptibility in the hippocampal slice preparation using 4-aminopyridine (4-AP) model of ictogenesis in inmature rats. We found that changing the medium perfusion rate in the range of 1-5 ml/min greatly affects the tissue oxygenation, amplitude and frequency of 4-AP-induced synchronous neuronal activity. The decrease in the flow rate as well as substitution of the oxygen in the extracellular medium with nitrogen causes a strong reduction of 4-AP-induced synchronous neuronal discharges. Our results demonstrate a significant linear correlation between the power of 4-AP-induced neuronal activity and the oxygen level in slice tissue. Also we demonstrated that the presence of medium flow is a necessary condition to support the constant level of the slice oxygenation. These data suggest that the oxygen supply of the brain slice strongly depends on experimental protocol and could modulate in vitro neuronal network excitability which should be taken into consideration when planning epilepsy-related studies.

Experimental Study of Inductive Pulsed Power Supply Based on Multiple HTSPPT Modules

For electromagnetic emission applications that need a very high amplitude and an appropriate pulsewidth, a pulsed power supply based on multiple high-temperature superconducting pulsed power transformer (HTSPPT) modules is verified in this paper. First, the working processes of multiple HTSPPT modules are analyzed and two small experimental HTSPPTs are described in detail. Then, simulation is carried out to show the major pulse characteristics of two different discharge methods. To verify the feasibility of two discharge methods, high-current testing is carried out with the two HTSPPTs. The results show that a higher amplitude of current pulse can be achieved using synchronous parallel discharge and a larger pulsewidth of current pulse can be achieved using asynchronous parallel discharge.

PM324. Case study on alcohol withdrawal with transient periodic synchronous discharge

PM324. Case study on alcohol withdrawal with transient periodic synchronous discharge

Specific clinical signs and symptoms are predictive of clinical course in sporadic Creutzfeldt-Jakob disease.

Background and purposeAkinetic mutism is thought to be an appropriate therapeutic end‐point in patients with sporadic Creutzfeldt−Jakob disease (sCJD). However, prognostic factors for akinetic mutism are unclear and clinical signs or symptoms that precede this condition have not been defined. The goal of this study was to identify prognostic factors for akinetic mutism and to clarify the order of clinical sign and symptom development prior to its onset.MethodsThe cumulative incidence of akinetic mutism and other clinical signs and symptoms was estimated based on Japanese CJD surveillance data (455 cases) collected from 2003 to 2008. A proportional hazards model was used to identify prognostic factors for the time to onset of akinetic mutism and other clinical signs and symptoms.ResultsPeriodic synchronous discharges on electroencephalography were present in the majority of cases (93.5%). The presence of psychiatric symptoms or cerebellar disturbance at sCJD diagnosis was associated with the development of akinetic mutism [hazard ratio (HR) 1.50, 95% confidence interval (CI) 1.14–1.99, and HR 2.15, 95% CI1.61–2.87, respectively]. The clinical course from cerebellar disturbance to myoclonus or akinetic mutism was classified into three types: (i) direct path, (ii) path via pyramidal or extrapyramidal dysfunction and (iii) path via psychiatric symptoms or visual disturbance.ConclusionsThe presence of psychiatric symptoms or cerebellar disturbance increased the risk of akinetic mutism of sCJD cases with probable MM/MV subtypes. Also, there appear to be sequential associations in the development of certain clinical signs and symptoms of this disease.

A new algorithm for epilepsy seizure onset detection and spread estimation from EEG signals

Appropriate diagnosis and treatment of epilepsy is a main public health issue. Patients suffering from this disease often exhibit different physical characterizations, which result from the synchronous and excessive discharge of a group of neurons in the cerebral cortex. Extracting this information using EEG signals is an important problem in biomedical signal processing. In this work we propose a new algorithm for seizure onset detection and spread estimation in epilepsy patients. The algorithm is based on a multilevel 1-D wavelet decomposition that captures the physiological brain frequency signals coupled with a generalized gaussian model. Preliminary experiments with signals from 30 epilepsy crisis and 11 subjects, suggest that the proposed methodology is a powerful tool for detecting the onset of epilepsy seizures with his spread across the brain.

Pathologic electrographic changes after experimental traumatic brain injury.

To investigate possible electroencephalography (EEG) correlates of epileptogenesis after traumatic brain injury (TBI) using the fluid percussion model. Experiments were conducted on adult 2- to 4-month-old male Sprague-Dawley rats. Two groups of animals were studied: (1) the TBI group with depth and screw electrodes implanted immediately after the fluid percussion injury (FPI) procedure, and (2) a naive age-matched control group with the same electrode implantation montage. Pairs of tungsten microelectrodes (50 μm outer diameter) and screw electrodes were implanted in neocortex inside the TBI core, areas adjacent to TBI, and remote areas. EEG activity, recorded on the day of FPI, and continuously for 2 weeks, was analyzed for possible electrographic biomarkers of epileptogenesis. Video-EEG monitoring was also performed continuously in the TBI group to capture electrographic and behavioral seizures until the caps came off (28-189 days), and for 1 week, at 2, 3, and 6 months of age, in the control group. Pathologic high-frequency oscillations (pHFOs) with a central frequency between 100 and 600 Hz, were recorded from microelectrodes, beginning during the first two post-FPI weeks, in 7 of 12 animals in the TBI group (58%) and never in the controls. pHFOs only occurred in cortical areas within or adjacent to the TBI core. These were associated with synchronous multiunit discharges and popSpikes, duration 15-40 msec. Repetitive pHFOs and EEG spikes (rHFOSs) formed paroxysmal activity, with a unique arcuate pattern, in the frequency band 10-16 Hz in the same areas as isolated pHFOs, and these events were also recorded by screw electrodes. Although loss of caps prevented long-term recordings from all rats, pHFOs and rHFOSs occurred during the first 2 weeks in all four animals that later developed seizures, and none of the rats without these events developed late seizures. pHFOs, similar to those associated with epileptogenesis in the status rat model of epilepsy, may also reflect epileptogenesis after FPI. rHFOSs could be noninvasive biomarkers of epileptogenesis.

Unfavorable surgical outcomes in partial epilepsy with secondary bilateral synchrony: Intracranial electroencephalography study

ObjectiveSecondary bilateral synchrony (SBS) indicates bilaterally synchronous epileptiform discharges arising from a focal cortical origin. The present study aims to investigate SBS in partial epilepsy with regard to surgical outcomes and intracranial EEG findings. MethodsWe retrospectively reviewed consecutive patients who underwent epilepsy surgery following extraoperative intracranial electroencephalography (EEG) study from 2008 to 2012. The presence of SBS was determined based upon the results of scalp EEG monitoring performed for presurgical evaluations. We reviewed scalp EEG, neuroimaging, intracranial EEG findings, and surgical outcomes in patients with SBS. ResultsWe found 12 patients with SBS who were surgically treated for intractable partial epilepsy. Nine (75%) patients had lateralized ictal semiology and only two (16.6%) patients showed localized ictal onset in scalp EEG. Brain MRI showed epileptogenic lesion in three (25%) patients. Intracranial EEG demonstrated that ictal onset zone was widespread or non-localized in six (50%) patients. Low-voltage fast activity was the most common ictal onset EEG pattern. Rapid propagation of ictal onset was noted in 10 (83.3%) patients. Eleven patients underwent resective epilepsy surgery and only two patients (18.2%) achieved seizure-freedom (median follow-up 56 months). MRI-visible brain lesions were associated with favorable outcomes (p=0.024). Patients with SBS, compared to frontal lobe epilepsy without SBS, showed lesser localization in ictal onset EEG (p=0.029) and more rapid propagation during evolution of ictal rhythm (p=0.015). ConclusionsThe present results suggested that resective surgery for partial epilepsy with SBS should be decided carefully, especially in case of nonlesional epilepsy. Poor localization and rapid spread of ictal onset were prominent in intracranial EEG, which might contribute to incomplete resection of the epileptogenic zone and poor surgical outcomes.

Cognitive Consequences in Children with Epilepsy

Some epilepsy is, in general, often associated with cognitive problems that can also affect a patient’s adjustments. Epileptic seizures result from an excessive, synchronous discharge of cerebral neurons. Interictal paroxysmal electroencephalogram (EEG) abnormalities are regarded as a correlate of persistent pathological neuronal discharges. Thus, correlation between cognitive deterioration and seizure severities/EEG paroxysmal abnormalities should be investigated. We have previously measured frontal/prefrontal lobe volumes using three-dimensional (3D)-magnetic resonance imaging (MRI) in children with benign childhood epilepsy with centrotemporal spikes, epilepsy with continuous spike-waves during slow sleep, frontal lobe epilepsy, and Panayiotopoulos syndrome, and confirmed that longer active seizure period as frequent spike-waves coupled with the occurrence of frequent seizures and presence of status epilepticus may be associated with prefrontal lobe growth disturbance, which relates to cognitive impairments. These findings suggest that seizure severities such as repeated seizures and presence of status epilepticus, and the subclinical paroxysmal EEG abnormalities may induce prefrontal lobe growth disturbance, which leads to intellectual impairments. Achieving better seizure control and remission for paroxysmal EEG abnormalities is a key to improve quality of life (QOL) in children with epilepsy. From the perspective of decreased cognitive problems and improving QOL, management may be required to remit seizures and paroxysmal EEG abnormalities as soon as possible to achieve optimal prognosis in epilepsy.

Intra- and Interhemispheric Propagation of Electrophysiological Synchronous Activity and Its Modulation by Serotonin in the Cingulate Cortex of Juvenile Mice.

Disinhibition of the cortex (e.g., by GABA -receptor blockade) generates synchronous and oscillatory electrophysiological activity that propagates along the cortex. We have studied, in brain slices of the cingulate cortex of mice (postnatal age 14–20 days), the propagation along layer 2/3 as well as the interhemispheric propagation through the corpus callosum of synchronous discharges recorded extracellularly and evoked in the presence of 10 μM bicuculline by electrical stimulation of layer 1. The latency of the responses obtained at the same distance from the stimulus electrode was longer in anterior cingulate cortex (ACC: 39.53 ± 2.83 ms, n = 7) than in retrosplenial cortex slices (RSC: 21.99 ± 2.75 ms, n = 5; p<0.05), which is equivalent to a lower propagation velocity in the dorso-ventral direction in ACC than in RSC slices (43.0 mm/s vs 72.9 mm/s). We studied the modulation of this propagation by serotonin. Serotonin significantly increased the latency of the intracortical synchronous discharges (18.9% in the ipsilateral hemisphere and 40.2% in the contralateral hemisphere), and also increased the interhemispheric propagation time by 86.4%. These actions of serotonin were mimicked by the activation of either 5-HT1B or 5-HT2A receptors, but not by the activation of the 5-HT1A subtype. These findings provide further knowledge about the propagation of synchronic electrical activity in the cerebral cortex, including its modulation by serotonin, and suggest the presence of deep differences between the ACC and RSC in the structure of the local cortical microcircuits underlying the propagation of synchronous discharges.

Reporting a Remarkable Visual Illusion Due to Temporal Lobe Epilepsy and an Unusual Response to Lamotrigine

Introduction: Visual illusions and hallucinations may accompany a wide variety of disorders with many various etiologies; therefore, they are nonspecific phenomena. In a partial seizure, a localized hyper synchronous neuronal discharge evolving into a partial seizure affecting a particular cortical region or cerebral subsystem can give rise to psychotic symptoms like visual hallucination. This case study introduces a patient with metamorphopsia, a rare visual illusion, that was treated with lamotrigine. Case Presentation: This case study introduces a 34-year-old man with a history of falling. After a while, his seizures became accompanied with aura and, during the attack, he saw people and objects as bloody. He was asymptomatic between the attacks, with no visceral feeling and with dysphoric mood and borderline IQ. He was resistant to various treatments. After 6 months administration of lamotrigine, he has not had any seizure attacks and the psychotic symptoms have improved. Conclusions: The psychotic symptoms due to temporal lobe epilepsy can be resolved with lamotrigine administration.

Isolated P/Q Calcium Channel Deletion in Layer VI Corticothalamic Neurons Generates Absence Epilepsy.

This study dissects a critical component of the corticothalamic circuit in spike-wave epilepsy and identifies the developmental importance of P/Q-type calcium channel-mediated presynaptic glutamate release at layer VI pyramidal neuron terminals. Genetic ablation of Cacna1a in layer VI neurons produced synchronous spike-wave discharges in the cortex and thalamus that were inhibited by ethosuximide. These mice also displayed N-type calcium channel compensation at descending thalamic synapses, and consistent with other spike-wave models increased low-threshold T-type calcium currents within postsynaptic thalamic relay and reticular neurons. These results demonstrate, for the first time, that preventing the developmental homeostatic switch from loose to tightly coupled synaptic release at a single class of deep layer cortical excitatory output neurons results in generalized spike-wave epilepsy.

VIDEO-EEG-MONITORING IN DIAGNOSIS OF MYOCLONIC ABSENCES

Myoclonic absences (MA) are generalised epileptic seizures, classificated as absences with special features. MA characterized by changes in the level of consciousness combined with severe bilaterally synchronous rhythmic myoclonic jerks. Objective. To study the clinical and electroencephalographic characteristics of MA. Materials and Methods. The study included 8 patients 5 to 13 years (5 female, 3 — male), in whom MA were registered during of video-EEG monitoring with the inclusion of sleep. Results. MA in wakefulness followed by stopping activity, hypomimia, the appearance of rhythmic bilateral myoclonic jerks in the muscles of the upper body and in some cases the tonic component (elevation of the arms) later joined. In 3 cases, unilateral myoclonus observed. Change in level of consciousness was able to identify if the seizure lasted for more than 5 seconds. EEG during MA in wakefulness has registered generalized bilaterally synchronous rhythmic discharges of sharp-slow wave or double / poly spike wave activity with amplitude predominance of discharges in the anterior areas. Rhythmic myoclonus coincided with a sharp wave, double-spikes, poly-spikes, complex “sharp-slow wave.” In 5 patients low amplitude fast activity (LAFA) was marked on EEG immediately before bilaterally synchronous complexes “sharp-slow wave.” In 7 cases during the sleep registered seizures with clinical and electroencephalographic characteristics of MA. It is impossible to adequately assess the level of consciousness during sleep. Conclusion. Nevertheless diagnosis absence during sleep is competent on the basis of two co-signs: changes in motor activity of the patient at the time of the EEG pattern of absences.