Synchronous Discharges Research Articles

Study of Oil/Pressboard Creeping Discharges Under Divergent AC Voltage—Part III: Effects of Temperature and Stress Type

The present article studies the effects of temperature and stress type on the oil/pressboard creeping discharge under divergent ac voltages. A ramp-stress test determines the short-time electric strengths of the oil/pressboard interface. Subsequently, long-term tests are carried out at different temperatures using constant and step stresses, respectively. Afterward, a novel methodology is proposed to detect the developing fault using synchronous partial discharge (PD) and online dielectric measurements. The interface short-time electric strengths correlate positively with the temperature. In long-term tests, the creeping discharges can generate three failure modes to oil/pressboard insulation: interface flashover (FO), surface tracking (ST), and internal treeing (IT). Different failure modes vary significantly in the discharge characteristics and the severities of damage to the pressboard. Temperature plays an important role in determining the failure modes of creeping discharge, and its influence mechanism is expounded in terms of the change of material properties, the interface of electric and dielectric phenomena, and their sophisticated interplays. The influence of stress type is related to the cumulative effect of stressing and the voltage rising steepness. The proposed methodology proves to be a potent tool in detecting the developing IT.

Myelination synchronizes cortical oscillations by consolidating parvalbumin-mediated phasic inhibition.

Parvalbumin-positive (PV+) γ-aminobutyric acid (GABA) interneurons are critically involved in producing rapid network oscillations and cortical microcircuit computations, but the significance of PV+ axon myelination to the temporal features of inhibition remains elusive. Here, using toxic and genetic mouse models of demyelination and dysmyelination, respectively, we find that loss of compact myelin reduces PV+ interneuron presynaptic terminals and increases failures, and the weak phasic inhibition of pyramidal neurons abolishes optogenetically driven gamma oscillations in vivo. Strikingly, during behaviors of quiet wakefulness selectively theta rhythms are amplified and accompanied by highly synchronized interictal epileptic discharges. In support of a causal role of impaired PV-mediated inhibition, optogenetic activation of myelin-deficient PV+ interneurons attenuated the power of slow theta rhythms and limited interictal spike occurrence. Thus, myelination of PV axons is required to consolidate fast inhibition of pyramidal neurons and enable behavioral state-dependent modulation of local circuit synchronization.

Animal Models of Epilepsy: A Phenotype-oriented Review.

Epilepsy is a serious neurological disorder characterized by abnormal, recurrent, and synchronous discharges in the brain. Long-term recurrent seizure attacks can cause serious damage to brain function, which is usually observed in patients with temporal lobe epilepsy. Controlling seizure attacks is vital for the treatment and prognosis of epilepsy. Animal models, such as the kindling model, which was the most widely used model in the past, allow the understanding of the potential epileptogenic mechanisms and selection of antiepileptic drugs. In recent years, various animal models of epilepsy have been established to mimic different seizure types, without clear merits and demerits. Accordingly, this review provides a summary of the views mentioned above, aiming to provide a reference for animal model selection.

Prenatal alcohol exposure affects developmental differentiation of interictal discharges in septal and temporal hippocampus.

Prenatal alcohol exposure (PAE) provokes lifelong CNS dysfunction, including an increased susceptibility to seizure disorders. We investigated hippocampal excitability in vitro in the offspring of dams exposed to a mild ethanol concentration throughout pregnancy (ethanol 15%v/v in drinking water). Hippocampal slices were prepared from the offspring at a young (Y, 21-30 postnatal days, PND) or adult (A, 60 PND) age, with controls from same age normal rats (N). Synchronous spontaneous interictal-type epileptiform discharges (IEDs) were induced by bathing the slices in Mg2+-free ACSF or in 4-Aminopyridine (4-AP, 50µΜ) and were recorded from CA1 pyramidal layer of temporal (T) and septal slices (S). Hippocampal slices readily generated IEDs following NMDA receptor activation or K+ conductance block, with frequency and duration depending on location (septal or temporal), age, the activating mechanism, and prior conditioning (N or PAE). From the two media, 4-AP induced higher frequency (always), shorter duration (mostly) IEDs compared to Mg 2+-free ACSF. Temporal IED frequency increased with age, whereas septal was stable, indicating an earlier maturation of the latter part. The hippocampal "T to S" (high to low) excitability gradient appeared at/later than the end of the first postnatal month and mostly concerned discharge frequency. Discharge duration generally decreased with maturation but appeared to depend on many factors, including conditioning. Prenatal alcohol exposure differentiated the control of synchronous discharges by NMDA receptors and K+ conductances, and their developmental evolution, thus suggesting potential mechanisms for aberrant hippocampal neuronal network function.

Progress of Autophagy in Epilepsy Research

Epilepsy is a clinical syndrome caused by highly synchronized abnormal discharges of neurons in the brain. It is a common disease of the nervous system. The pathogenesis of epilepsy has not been fully understood yet. The main pathological changes after seizures are programmed neuronal death and glial proliferation. Autophagy is a catabolic process. Moderate autophagy is critical to maintain the homeostasis and cell health, while abnormal autophagy can lead to disease. A number of studies have proved that abnormal autophagy mechanism can lead to epilepsy, and there are also literatures that autophagy induced by endoplasmic reticulum stress can reduce the neuronal damage triggered by epilepsy, thus playing a protective role in neurons. This article reviews the relationship between autophagy and epilepsy in order to provide basis for further study of autophagy pathway and pathophysiology of epilepsy.

МНОГОФУНКЦИОНАЛЬНАЯ МАГНИТНО - ИМПУЛЬСНАЯ УСТАНОВКА С ИЗМЕНЯЕМОЙ ФОРМОЙ И ПАРАМЕТРАМИ РАЗРЯДНОГО ТОКА

The paper considers methods and circuitry for creating a multifunctional pulse-magnetic installation with variable parameters of the discharge current for forming of pulsed magnetic fields. The installation is designed to conduct comprehensive research on the effect of the magnetic field on various materials in mechanical engineering, medicine, pharmacology and plant growing. Currently, traditional designs of the installations operate in a single-discharge mode and generate oscillatory shaped pulses of current in the form of a damped sinusoid. The developed installation with power intensity of 5 kJ operates in four modes: oscillatory discharge of one energy storage device with a high frequency of the discharge current, synchronous discharge of two energy storage devices, asynchronous discharge of two storage devices with an adjustable delay relative to each other, and in the mode of forming a mono-pulse with a cutoff of the current of subsequent half-cycles. The paper presents the block diagram of the multifunctional pulse-magnetic installation (PMI), provides recommendations on the selection of the main components when creating specialized installations for solving specific tasks. The results of testing the PMI are given.

Comparative Study on Characteristics of Partial Discharge Optical Pulse and UHF Pulse in Switch Equipment

The article explores the performance of the new silicon photoelectric sensor in partial discharge detection, and compares the measured optical pulse with the traditional UHF pulse. Through optical and electrical synchronous partial discharge experiments, the article analyzes and discusses the detection performance, working characteristics and statistical characteristics of various sensors, and explores the advantages and feasibility of silicon photoelectric partial discharge sensors in actual discharge monitoring; In addition, the statistical performance of the two physical phenomena of partial light radiation and electromagnetic radiation was obtained through the analysis of optical and electrical synchronous monitoring data. Compared with UHF sensor, silicon photoelectric sensor under the optimal working voltage has a higher signal-to-noise ratio (SNR); Under the electromagnetic interference of the high-frequency motor, silicon photoelectric sensor exhibits better anti-electromagnetic interference ability; Discharge phase interval and characteristics reflected by the PRPD obtained by two detection methods maintain good consistency; Pulse repetition rate has the same trend with applied voltage, but statistical frequency of optical pulses obtained is higher than that of electromagnetic pulses because silicon photoelectric sensor has a higher SNR and single-photon sensitivity.

Childhood absence epilepsy: Electro-clinical manifestations, treatment options, and outcome in a tertiary educational center.

Purpose and BackgroundTo evaluate the electro-clinical manifestations and outcomes of children with absence epilepsy at a tertiary center in Saudi Arabia.MethodsThis retrospective study reviewed the medical and EEG records of patients who were diagnosed to have CAE as per the International League Against Epilepsy (ILAE) definition for CAE. The study was conducted in the pediatric neurology clinic of King Khalid University Hospital, King Saud University Medical City, Riyadh, Saudi Arabia, between January 2000 and December 2019. Patients who did not meet (ILAE) criteria, lost follow-up, and those who did not receive treatment at KKUH were excluded. Data regarding the patient's disease, electro-clinical manifestations, anti-seizure medication response, and outcomes were collected.ResultsA total of 35 patients, with an average age at diagnosis of 7 ± 2.1 y, were included in the study; among them, 51.4% were female and approximately 48.6% presented with a family history of epilepsy. Regarding clinical features, all patients experienced staring and altered awareness, 94.2% had less than 20 spells per day at the time of diagnosis, and 65.7% were provoked by the hyperventilation test. Regarding EEG findings, all patients had bilateral, symmetrical, and synchronous discharges in the form of regular 3 Hz spike-and-wave complexes, and 94.3% had a generalized initial ictal discharge. Also, 22.8% had eye fluttering with electrographic seizures. Ethosuximide (ESM) was used as the drug of choice in 45.7% of the patients. Regarding clinical outcomes, 94.3% had their disease clinically controlled, and 80% had a normalized EEG after few months of starting anti-seizure medication. Finally, 37.2% experienced complete remission of epilepsy after 3–5 y; however, one patient developed juvenile myoclonic epilepsy.ConclusionThis study described the electro-clinical manifestations of patients with childhood absence epilepsy and outcomes. Furthermore, early diagnosis and prompt treatment of childhood absence epilepsy improve treatment outcomes.

Neonatal Seizures: Core Concepts.

Seizures are the abnormal, excessive, synchronous discharge of cortical neurons that results in injury to the brain. Seizures presenting in the neonatal period may be the first and only clue to underlying neurological pathology. Despite advances in care, the mortality rate for infants experiencing neonatal seizures is still as high as 20 percent, with up to 65 percent of infants with seizures demonstrating significant morbidity. Early identification and treatment of the seizure or modifiable underlying etiology greatly reduces the extent of morbidity associated with neonatal seizures. Literature, including journal articles and relevant textbooks, was reviewed and condensed into a practical guide to neonatal seizures which includes the pathophysiology of injury associated with neonatal seizures, clinical manifestations, methods of diagnosis, and various options available for treatment.

Development of hand-held needle–ring–ring self-excited plasma device

Copper is deposited in the holes of two perforated printed circuit boards to form copper rings with a width of 1.5 mm, a thickness of 1.6 mm, and diameters of 10 and 7 mm, respectively. The resulting structures form ground electrodes. A plate with a diameter of 10 mm is placed above a plate with a diameter of 7 mm to ensure that the distance between the two electrode rings is 2.5 mm. Meanwhile, a tungsten needle with a diameter of 1.1 mm is placed 6 mm directly above the coaxial position of the 7 mm diameter plate as the needle electrode. The needle–ring–ring electrode structure is designed to achieve stable synchronous discharge from each unit. The shell of the device is made using 3D printing technology. The displacement of active substances on the agar plate by the needle–ring–ring self-excited plasma jet is visualized using the starch–potassium iodide reagent. The results indicate that the device produces a better sterilization effect than traditional sterilizing devices and that no hollow, annular, unsterilized part is produced. In addition, the macroscopic temperature of the self-excited emission stream is detected. The human body detects no obvious burning or tactile sensation from the plasma.

Los potenciales evocados auditivos de estado estable a múltiples frecuencias y su valor en la evaluación objetiva de la audición

Uno de los principales objetivos en la realización de un examen electroaudiométrico es la obtención de una evaluación frecuencia específico de los umbrales de audibilidad. En las últimas décadas han sido propuestas múltiples técnicas basadas en el registro de los Potenciales Evocados Auditivos (PEA). Los mismos no son afectados por la sedación ni el sueño y pueden ser detectados a intensidades de estimulación muy cercanas al umbral de audibilidad. Las ventajas antes mencionadas lo han convertido en una útil herramienta para la evaluación objetiva de la audición. No obstante, esta técnica tiene ciertas limitaciones desde el punto de vista electroaudiométrico, debido principalmente a la falta de frecuencia especificada de dicha respuesta.
 Los Potenciales Evocados Auditivos de Estado Estable (PEAee) por estímulos tonales aislados y a frecuencias de estimulación entre 75 y 110 Hz han sido propuestos como una alternativa valida para la realización de una audiometría frecuencia especifica. Este tipo de respuesta representa la descarga sincrónica de las neuronas del tronco cerebral, las cuales siguen la frecuencia de modulación del estimulo que les da origen.
 Múltiples han sido los autores que en los últimos años y usando este tipo de respuesta han obtenido estimaciones confiables del umbral de audibilidad tonal, tanto en niños y adultos sanos como en sujetos hipoacúsicos. Esta técnica tiene múltiples ventajas sobre los PEA transitorios en la determinación de umbrales específicos en frecuencia: 1) Dado la periodicidad de la respuesta esta puede ser representada en el dominio de la frecuencia, minimizando por ende la complejidad de su medición, 2) El estimulo acústico empleado es mas especifico en frecuencia, 3) Debido a las propiedades de rectificación de la coclea la respuesta provocada por un tono modulado en amplitud es representada como un pico espectral a la frecuencia de modulación, 4) Estos picos espectrales pueden ser detectados usando diferentes estadígrafos en el dominio de la frecuencia.
 A pesar de las ventajas anteriormente descritas, la obtención de un audiograma completo mediante el uso de los PEAee provocados por estímulos tonales aislados puede requerir un gran consumo de tiempo. Más recientemente ha sido propuesta una variante optimizada de los PEAee entre 75 y 110 Hz con el empleo simultaneo de múltiples tonos modulados en amplitud. Dado el hecho que cada tono portador es modulado con una frecuencia diferente, múltiples tonos pueden ser entonces sumados, formando un tono complejo compuesto por múltiples tonos modulados en amplitud. Usando entonces como estimulo, una mezcla compuesta por tonos de 500, 1000, 2000 y 4000 Hz podemos activar y evaluar simultáneamente estas cuatro regiones de frecuencia de la cóclea. Por otra parte, estos estímulos complejos pueden ser presentados binauralmente, evaluando ambos oídos simultáneamente.
 Los PEAee provocados por múltiples tonos modulados en amplitud han sido empleados con alentadores resultados en la determinación objetiva de los umbrales de audibilidad en niños y adultos, pacientes hipoacúsicos y en la detección temprana de defectos auditivos. El presente artículo resume algunos conceptos básicos, así como sus aplicaciones clínicas.

Interictal Spikes as an EEG Biomarker of Cognitive Impairment.

Although interictal spikes (IISs) are a well-established EEG biomarker for epilepsy, whether they are also a biomarker of cognitive deficits is unclear. Interictal spikes are dynamic events consisting of a synchronous discharge of neurons producing high frequency oscillations and a succession of action potentials which disrupt the ongoing neural activity. There are robust data showing that IISs result in transitory cognitive impairment with the type of deficit specific to the cognitive task and anatomic location of the IIS. Interictal spike, particularly if frequent and widespread, can impair cognitive abilities, through interference with waking learning and memory and memory consolidation during sleep. Interictal spikes seem to be particularly concerning in the developing brain where animal data suggest that IISs can lead to adverse cognitive effects even after the disappearance of the spikes. Whether a similar phenomenon occurs in human beings is unclear. Thus, although IISs are a clear biomarker of transitory cognitive impairment, currently, they lack sensitivity and specificity as a biomarker for enduring cognitive impairment.

DNA Methylation Signature of Epileptic Encephalopathy-Related Pathogenic Genes Encoding Ion Channels in Temporal Lobe Epilepsy.

Epilepsy is characterized by highly abnormal synchronous discharge of brain neurons, and ion channels are fundamental in the generation and modulation of neural excitability. Considering that abnormal methylation can either activate or repress genes, this study was designed to explore the DNA methylation signature of pathogenic genes encoding ion channels in temporal lobe epilepsy (TLE). In total, 38 TLE patients and 38 healthy controls were enrolled in the study, and genomic DNA and total protein of the lymphocytes were extracted from peripheral blood samples to assess methylation and protein levels. The DNA methylation levels of all 12 genes examined were significantly lower in the TLE group than in the control group. After false-positive correction, 83.3% (10/12) of these genes, namely, gamma-aminobutyric acid type A receptor subunit beta1 (GABRB1), gamma-aminobutyric acid type A receptor subunit beta2 (GABRB2), gamma-aminobutyric acid type A receptor subunit beta1 (GABRB3), glutamate ionotropic receptor NMDA type subunit 1 (GRIN1), glutamate ionotropic receptor NMDA type subunit 2A (GRIN2A), glutamate ionotropic receptor NMDA type subunit 2B (GRIN2B), hyperpolarization activated cyclic nucleotide gated potassium channel 1 (HCN1), potassium voltage-gated channel subfamily A member 2 (KCNA2), potassium voltage-gated channel subfamily B member 1 (KCNB1), and potassium sodium-activated channel subfamily T member 1 (KCNT1), were still differentially expressed. Among these ion channels, HCN1 and KCNA2 were selected to evaluate the effects of DNA methylation, and the levels of these proteins were inversely upregulated in the TLE group compared to the control group. As the genes identified as having differential methylation levels are involved in both excitatory and inhibitory ion channels, this study observed by binary logistic regression that hypermethylated GARAB1 was an independent risk factor for TLE, indicating that the overwhelming effect of ion channels on TLE is probably inhibitory from the perspective of DNA methylation. All these findings support the involvement of DNA methylation in TLE pathologies, but the mechanisms need to be further investigated.

Phoenixin-14 reduces the frequency of interictal-like events in mice brain slices

Phoenixin-14 (PNX-14) has a wide bioactivity in the central nervous system. Its role in the hypothalamus has been investigated, and it has been reported that it is involved in the regulation of excitability in hypothalamic neurons. However, its role in the regulation of excitability in entorhinal cortex and the hippocampus is unknown. In this study, we investigated whether i. PNX-14 induces any synchronous discharges or epileptiform activity and ii. PNX-14 has any effect on already initiated epileptiform discharges. We used 350 µm thick acute horizontal hippocampal-entorhinal cortex slices obtained from 30- to 35-day-old mice. Extracellular field potential recordings were evaluated in the entorhinal cortex and hippocampus CA1 region. Bath application of PNX-14 did not initiate any epileptiform activity or abnormal discharges. 4-Aminopyridine was applied to induce epileptiform activity in the slices. We found that 200nM PNX-14 reduced the frequency of interictal-like events in both the entorhinal cortex and hippocampus CA1 region which was induced by 4-aminopyridine. Furthermore, PNX-14 led to a similar suppression in the total power of local field potentials of 1-120Hz. The frequency or the duration of the ictal events was not affected. These results exhibited for the first time that PNX-14 has a modulatory effect on synchronized neuronal discharges which should be considered in future therapeutic approaches.

WS1.4. Generalized Epilep tiform Patterns – Interictal and Ictal: Defining the Clinical Syndrome

Generalised epileptiform patterns (GEPs) are bilateral and synchronous epileptiform discharges that appear over corresponding parts of both hemispheres, or the whole brain. Their morphology, amplitude and timing should be the same or similar over both hemispheres. The distinction between ictal and interictal GEPs is generally less clear compared with focal patterns. Ictal patterns often represent longer repetitions of interictal patterns. Clinical signs are more likely to be apparent during GEPs if the bursts are longer, the spike component is more persistent, and tests of responsiveness are adequately and repeatedly tested by the EEG technician. GEPs include 3Hz spike-wave discharges, polyspike-wave discharges, slow spike- wave discharges, generalised paroxysmal fast activity, electrodecremental response, photosensitive responses and ictal patterns. 3Hz spike and wave complexes are characteristic of idiopathic (genetic) generalised epilepsy, which includes childhood absence, juvenile absence and juvenile myoclonic epilepsy as well as epilepsy with generalised tonic-clonic seizures only. In children with 3Hz spike and wave, spontaneous remission is more likely if there is co-existent OIRDA and less likely if there is co-existent photoparoxysmal responses. Polyspike and wave complexes, either single or repetitive, can be seen in both idiopathic (typically in JME) and symptomatic generalised epilepsies. Slow spike and wave complexes occur at a frequency of 1.5–2.5 Hz and usually arise from an abnormal background; they, along with generalised paroxysmal fast activity (GPFA-bilaterally synchronous10–25 Hz activity) are typically seen in symptomatic and cryptogenic generalised epilepsies, notably Lennox-Gastaut syndrome. GPFA is typically seen in tonic seizures, but may also accompany atonic and generalised tonic-clonic seizures. Electrodecremental responses are seen in the atonic and tonic seizures of symptomatic and cryptogenic generalised epilepsies. Photoparoxysmal responses are bursts of generalised spike or polyspike and wave discharges that appear at certain flash frequencies and may outlast the stimulus.

Motor Dysfunction of Autonomic Nervous System Based on Resting State Functional Magnetic Resonance Imaging

Epilepsy is caused by highly synchronized abnormal discharges of neurons in the brain. Resting State FMRI is widely used as a non-invasive checking method, clinical and basic research in the field of epilepsy has a huge influence, to study the plant nerve system movement function of brain activity and the neural network function of the complex contact provides broad prospects, greatly promote the development of clinical neurology and imaging. Therefore, this paper studies the functional connection and cognitive function of verbal working memory (VWM) in patients with epilepsy by applying resting state FMRI. The experimental results showed that VWM and cognitive functions of epileptic patients showed a trend of decline or even disappearance, to realize the detection of autonomic nervous system motor dysfunction of patients.

Status Triphasicus Versus Status Epilepticus?

Generalized periodic patterns with triphasic wave morphology, long referred to as triphasic waves [TWs], had been associated with metabolic encephalopathies, although other neurologic and systemic causes have since been identified. In a recent classification of periodic patterns, TWs were formally grouped with the generalized periodic discharges, which are often associated with ictal activity. The interpretation of generalized periodic patterns with TWs as nonictal can have significant implications in the management of comatose patients in nonconvulsive status epilepticus. Electrographic characteristics that help distinguish nonictal periodic patterns with TWs from generalized periodic discharge ictal patterns include (1) TWs in long runs of periodic bilaterally synchronous and symmetric discharges, maximal in frontocentral or posterior head regions with and without a frontal-to-occipital lag or posterior-to-anterior lag, respectively; (2) recurrent spontaneous and/or low-dose benzodiazepine-induced attenuation and/or suppression of the periodic pattern and replacement with a diffuse slow wave activity throughout a prolonged EEG recording; and (3) stimulation-induced activation and/or increase in frequency and/or organization of TWs. We coined the term of status triphasicus to describe the electrographic periodic pattern of TWs with these three distinct characteristics. In this article, we discuss the advantages and limitations of keeping the status triphasicus pattern as a distinct electrographic entity different from periodic ictal generalized periodic discharge patterns. We discuss the circumstances in which a status triphasicus pattern can be associated with ictal activity and propose a simple pragmatic classification of status triphasicus that encompasses the different clinical scenarios it can be associated with.

CDDO-Me Attenuates Astroglial Autophagy via Nrf2-, ERK1/2-SP1- and Src-CK2-PTEN-PI3K/AKT-Mediated Signaling Pathways in the Hippocampus of Chronic Epilepsy Rats.

Clasmatodendrosis is an autophagic astroglial death showing extensive swollen cell bodies with vacuoles and disintegrated/beaded processes. This astroglial degeneration is closely relevant to the synchronous epileptiform discharges. However, the underlying molecular mechanisms and the roles of clasmatodendrosis in spontaneous seizure activity are still unknown. The 2-cyano-3,12-dioxo-oleana-1,9(11)-dien-28-oic acid methyl ester (CDDO-Me; RTA 402) is one of the activators for nuclear factor-erythroid 2-related factor 2 (Nrf2) that is a redox-sensitive transcription factor. In the present study, we explored the effects of CDDO-Me on clasmatodendrosis in chronic epilepsy rats, which could prevent epilepsy-related complications. In the present study, clasmatodendritic astrocytes showed reduced Nrf2 expression and its nuclear accumulation, which were restored by CDDO-Me. CDDO-Me also abrogated heat shock protein 25 (HSP25) upregulation in clasmatodendritic astrocytes by regulating extracellular signal-related kinases 1/2 (ERK1/2)-specificity protein 1 (SP1)- and Src-casein kinase 2 (CK2)-phosphatase and tensin homolog deleted on chromosome 10 (PTEN)-phosphatidylinositol-3-kinase (PI3K)-AKT-glycogen synthase kinase 3β (GSK3β)-bax-interacting factor 1 (Bif-1)-mediated signaling pathways in chronic epilepsy rats. In addition, CDDO-Me ameliorated spontaneous seizure duration, but not seizure frequency and behavioral seizure severity. Therefore, our findings suggest that clasmatodendrosis may affect seizure duration in chronic epilepsy rats, and that CDDO-Me may attenuate autophagic astroglial degeneration by regulating various signaling pathways.

A characteristic occipital epileptiform EEG pattern in ADCK3-related mitochondrial disease.

ADCK3-related disease is a mitochondrial disorder associated with an abnormality of coenzyme Q10 metabolism. Ataxia and epilepsy are common, and the phenotype overlaps with other mitochondrial encephalopathies, particularly POLG-related disease. CoQ10 supplementation may be beneficial. We have noted a remarkable epileptiform pattern in ADCK3-related encephalopathy, and since EEG studies in this rare condition are limited, we wished to assess the evolution of EEG characteristics in patients with this disorder. All EEG recordings of the four known patients from Mid-Norway were systematically reviewed. EEG graphoelements were classified according to the standardized computer-based organized reporting of EEG (SCORE) and international glossary terms. The evolution of EEG features was assessed. A total of 96 recordings spanning over 15-32 years were available, with a mean of 24 per patient (range: 17-28). Altogether, 50 digital recordings were reviewed, including four long-term and 46 selected paper segments. In three patients, EEG showed prominent bilateral asynchronous and synchronous epileptiform discharges in occipital and posterior-temporal regions. This intense activity included multiple epileptiform graphoelements, which occurred continuously, nearly continuously or in prolonged runs. The findings remained stable over many years. Although the number of patients is small, we suggest that interictal EEG findings of continuous/nearly continuous bi-occipital spike-waves may serve as a biomarker for this potentially treatable condition. This peculiar EEG pattern might help to differentiate ADCK3-related disease from the more common POLG-related disease, which is usually characterized by lateralized or focal slowing with more sporadic epileptiform elements of similar topography.

Subiculum as a generator of sharp wave-ripples in the rodent hippocampus.

SUMMARYSharp wave-ripples (SWRs) represent synchronous discharges of hippocampal neurons and are believed to play a major role in memory consolidation. A large body of evidence suggests that SWRs are exclusively generated in the CA3-CA2 network. In contrast, here, we provide several lines of evidence showing that the subiculum can function as a secondary SWRs generator. SWRs with subicular origin propagate forward into the entorhinal cortex as well as backward into the hippocampus proper. Our findings suggest that the output structures of the hippocampus are not only passively facilitating the transfer of SWRs to the cortex, but they also can actively contribute to the genesis of SWRs. We hypothesize that SWRs with a subicular origin may be important for the consolidation of information conveyed to the hippocampus via the temporoammonic pathway.