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International audience; Montazeri Moghadam et al. report an automated algorithm to visually convert EEG recordings to real-time quantified interpretations of EEG in neonates. The resulting measure of the brain state of the newborn (BSN) bridges several gaps in neurocritical care monitoring.

To determine the prognostic value of conventional electroencephalography (EEG) monitoring in neonatal hypoxic-ischemic encephalopathy (HIE).In this multicentre retrospective study, 95 full-term neonates (mean of 39.3wks gestational age [SD 1.4], 36 [38%] females, 59 [62%] males) with HIE (2013-2016) undergoing therapeutic hypothermia were divided between favourable or adverse outcomes. Background EEG activity (French classification scale: 0-1-2-3-4-5) and epileptic seizure burden (epileptic seizure scale: 0-1-2) were graded for seven 6-hour periods. Conventional EEG monitoring was investigated by principal component analysis (PCA), with clustering methods to extract prognostic biomarkers of development at 2 years and infant death.Eighty-one per cent of infants with an adverse outcome had a French classification scale equal to or greater than 3 after H48 (100% at H6-12). The H6-12 epileptic seizure scale was equal to or greater than 1 for 39%, increased to 52% at H30-36 and then remained equal to or greater than 1 for 39% after H48. Forty-five per cent of infants with a favourable outcome had a H6-12 French classification scale equal to or greater than 3, which dropped to 5% after H48; 13% had a H6-12 epileptic seizure scale equal to or greater than 1 but no seizures after H48. Clustering methods based on PCA showed the high efficiency (96%) of conventional EEG monitoring for outcome prediction and allowed the definition of three prognostic EEG biomarkers: H6-78 French classification scale mean, H6-78 French classification scale slope, and H30-78 epileptic seizure scale mean.Early lability and recovery of physiological features is prognostic of a favourable outcome. Seizure onset from the second day should also be considered to accurately predict neurodevelopment in HIE and support the importance of conventional EEG monitoring in HIE in infants cooled with therapeutic hypothermia.Comprehensive analysis showed the high prognostic efficiency (96%) of conventional electroencephalography (EEG) monitoring. Prognostic EEG biomarkers consist of the grade of background EEG activity, its evolution, and the mean seizure burden. Persistent seizures (H48) without an improvement in background EEG activity were consistently associated with an adverse outcome.

Electroencephalography (EEG) is the reference tool for the analysis of brain function, reflecting normal and pathological neuronal network activity. During the neonatal period, EEG patterns evolve weekly, according to gestational age. The first analytical criteria for the various maturational stages and standardized neonatal EEG terminology were published by a group of French neurophysiologists training in Paris (France) in 1999. These criteria, defined from analog EEG, were completed in 2010 with digital EEG analysis. Since then, this work has continued, aided by the technical progress in EEG acquisition, the improvement of knowledge on the maturating processes of neuronal networks, and the evolution of critical care. In this review, we present an exhaustive and didactic overview of EEG characteristics from extremely premature to full-term infants. This update is based on the scientific literature, enhanced by the study of normal EEGs of extremely premature infants by our group of neurophysiologists. For educational purposes, particular attention has been paid to illustrations using new digital tools.

International audience; Sleep is a key process in neurodevelopment and essential for the maturation of fundamental brain functions. Premature birth can disturb the initial steps of sleep maturation, which may contribute to the impairment of neurodevelopment. It is thus fundamental to understand the maturation of the various sleep states and the quality of cerebral function in each vigilance state, as well as the development of sleep cyclicity, in at-risk neonatal infants, particularly those born premature. The objective of this review is to provide a precise description of sleep states and cycles and their rhythmic organization in premature and term newborns according to their gestational age. Technical aspects of polysomnography, which requires a high level of expertise in neonates, are also described. Principles of the visual interpretation of polysomnography, including the simultaneous analysis of behavioral (spontaneous motricity and eye movements), polysomnographic parameters (electro-oculogram, electrocardiogram, respiration), and electroencephalography patterns are presented. The neurophysiology of sleep ontogenesis and its interaction with brain maturation are discussed, highlighting the crucial-role of sleep states and their duration in premature newborns. In particular, the involvement of myoclonic twitches in functional connectivity in sensorimotor development is discussed. Indeed, sleep quality, determined by combined polysomnographic parameters, reflects either normal or pathological developmental processes during the neonatal period. The fundamental place of neurophysiological explorations in the early detection of sleep disorders is discussed, as well as their potential consequences on neurodevelopmental care to improve the prevention of neurodevelopmental impairment. (C) 2020 Elsevier Masson SAS. All rights reserved.

Electroencephalography (EEG) of neonatal patients is amongst the most valuable diagnostic and prognostic tool. EEG recordings, acquired at the bedside of infants, evaluate brain function and the maturation of premature and extremely premature infants. Strict conditions of acquisition and interpretation must be respected to guarantee the quality of the EEG and ensure its safety for fragile children. This article provides guidance for EEG acquisition including: (1) the required equipment and devices, (2) the modalities of installation and asepsis precautions, and (3) the digital signal acquisition parameters to use during the recording. The fundamental role of a well-trained technician in supervising the EEG recording is emphasized. In parallel to the acquisition recommendations, we present a guideline for EEG interpretation and reporting. The successive steps of EEG interpretation, from reading the EEG to writing the report, are described. The complexity of the EEG signal in neonates makes artefact detection difficult. Thus, we provide an overview of certain characteristic artefacts and detail the methods for eliminating them.

International audience; We report on a 7-year-old female who presented paroxysmal episodes of loss of consciousness with clonic movements. The electroencephalogram (EEG) evidenced diffuse slow wave activations, with no symptoms. Epilepsy was suspected but antiepileptic drugs were ineffective. Video-EEG monitoring revealed that the syncope was triggered by stretching with a tachycardia that started during the stretch maneuver and diffuse slow waves on the EEG 2s before the symptoms. Stretch syncope can result in striking manifestations with subcortically driven clonic movements that can be mistaken for signs of epilepsy. Stretching might lead to transient hypoxia of the brainstem; in turn, this might activate the thalamocortical loop and thus generate cardiovascular changes, EEG slow waves, and physical manifestations.

Electroencephalography is the only clinically available technique that can address the premature neonate normal and pathological functional development week after week. The changes in the electroencephalogram (EEG) result from gradual structural and functional modifications that arise during the last trimester of pregnancy. Here, we review the structural changes over time that underlie the establishment of functional immature neural networks, the impact of certain anatomical specificities (fontanelles, connectivity, etc.) on the EEG, limitations in EEG interpretation, and the utility of high-resolution EEG (HR-EEG) in premature newborns (a promising technique with a high degree of spatiotemporal resolution). In particular, we classify EEG features according to whether they are manifestations of endogenous generators (i.e. theta activities that coalesce with a slow wave or delta brushes) or come from a broader network. Furthermore, we review publications on EEG in premature animals because the data provide a better understanding of what is happening in premature newborns. We then discuss the results and limitations of functional connectivity analyses in premature newborns. Lastly, we report on the magnetoelectroencephalographic studies of brain activity in the fetus. A better understanding of complex interactions at various structural and functional levels during normal neurodevelopment (as assessed using electroencephalography as a benchmark method) might lead to better clinical care and monitoring for premature neonates.

Objective: Characterization of the spatial and temporal dynamics of interictal epileptic discharges (IED) using time-frequency analysis (TFA) and electrical-source localization (ESL). Methods: TFA was performed on IED (spikes, spike waves, and polyspike waves) recorded by high-density-EEG (HD-EEG) in 19 refractory focal epileptic children. Temporal modulations related to IEDs were analyzed in a time window around the IED peaks [-1,000 to 1,000 ms]. Spatial modulations were analyzed by ESL in the time-frequency and time domains. Results: IED were associated with complex power spectral modulations. We observed increases in power spectrum (IPS) patterns specific to IED type. For spikes, the TFA pattern consisted of an IPS (-100 to +100 ms, 4-50 Hz). For spike waves, the IPS was followed by a second IPS (+100 to +400 ms, 4-10 Hz), corresponding to the slow wave. IPS patterns were preceded (-400 to -100 ms, 4-40 Hz), and followed (+100 to +400 ms) by a decrease in the power spectrum (DPS) (n = 8). For 14 out of 19 patients, at least one ESL method was concordant with the epileptogenic area. For the remaining five patients, all of them had temporal epilepsies. ESL in the time-frequency domain (DPS/IPS) provided concordant (n = 6) or complementary (n = 4) information to the ESL in the time domain concerning the epileptogenic zone. ESL in time-frequency domain (DPS/IPS) was the only method to provide concordant information concerning the epileptogenic zone in three patients. Significance: TFA demonstrates complex time-frequency modulations of the neuronal networks around IED, suggesting that the pathological mechanisms are initiated well before onset of the classical hyper-synchronization of the IED. Combining time and time-frequency analysis of the ESL provides complementary information to define the epileptogenic zone in refractory focal epilepsy.

Epilepsy is a neurological disorder characterized by abnormal electrical discharges in a group of brain cells. Benign childhood epilepsy, which affect children under the age of 12 years, has been reported to contribute to the cognitive impairment of these children, even in the absence of structural abnormalities. Functional connectivity models have been applied to provide a deeper understanding of the processes that control and regulate interictal activity of benign childhood epilepsy. These studies have shown regions of increased connectivity and activity, particularly at the epileptic zone, which is usually the central region around the sensorimotor cortex, and in the immediate regions surrounding the zone and reduced activity in distant regions, such as the frontal lobe and temporal regions. The present study was designed to identify the neural drivers involved in the initiation and propagation of epileptic activity and the causal relationships between brain regions with increased and decreased connectivity and functional activity. We used three different models to identify neural drivers and casual connectivity with dynamic causal modelling (DCM) of EEG data. All models showed that the central region, the source of the epileptic activity, is the major driver of the brain network during interictal discharges. Other regions include the temporoparietal junction and temporal pole. The central region also had influence on the frontal and contralateral hemisphere, which might explain the cognitive deficits observed in these patients., Highlights • The epileptic source is the major driver of the brain network • Other drivers include the temporoparietal junction and temporal pole • Epileptic source had influence on the frontal region which might explain the cognitive deficits • The right epileptic region drives the left hemisphere during interictal epileptic discharges

SummaryObjective Interictal epileptic spikes (IES) represent a signature of the transient synchronous and excessive discharge of a large ensemble of cortical heterogeneous neurons. Epilepsy cannot be reduced to a hypersynchronous activation of neurons whose functioning is impaired, resulting on electroencephalogram (EEG) in epileptic seizures or IES. The complex pathophysiological mechanisms require a global approach to the interactions between neural synaptic and nonsynaptic, vascular, and metabolic systems. In the present study, we focused on the interaction between synaptic and nonsynaptic mechanisms through the simultaneous noninvasive multimodal multiscale recording of high-density EEG (HD-EEG; synaptic) and fast optical signal (FOS; nonsynaptic), which evaluate rapid changes in light scattering related to changes in membrane configuration occurring during neuronal activation of IES. Methods To evaluate changes in light scattering occurring around IES, three children with frontal IES were simultaneously recorded with HD-EEG and FOS. To evaluate change in synchronization, time–frequency representation analysis of the HD-EEG was performed simultaneously around the IES. To independently evaluate our multimodal method, a control experiment with somatosensory stimuli was designed and applied to five healthy volunteers. Results Alternating increase–decrease–increase in optical signals occurred 200 ms before to 180 ms after the IES peak. These changes started before any changes in EEG signal. In addition, time–frequency domain EEG analysis revealed alternating decrease–increase–decrease in the EEG spectral power concomitantly with changes in the optical signal during IES. These results suggest a relationship between (de)synchronization and neuronal volume changes in frontal lobe epilepsy during IES. Significance These changes in the neuronal environment around IES in frontal lobe epilepsy observed in children, as they have been in rats, raise new questions about the synaptic/nonsynaptic mechanisms that propel the neurons to hypersynchronization, as occurs during IES. We further demonstrate that this noninvasive multiscale multimodal approach is suitable for studying the pathophysiology of the IES in patients.

Surgery is increasingly proposed as a treatment for children with medically refractory partial epilepsy. The outcome after surgery depends on complete resection of the epileptogenic zone correlates. Despite multimodal preoperative assessment, 40–60% of children require intracranial electroencephalography (EEG) recording. Standard EEG can be easily performed with 20 to 30 electrodes in children of all ages. Increasing the number of electrodes (high-density [HD] EEG) significantly improves the spatial resolution of EEG and allows source localization of the epileptogenic focus. In adults, this technique has been validated for source localization of the epileptic focus and contributes to a better understanding of the neural networks involved in epilepsy. In this review, we discuss the pediatric specificities of HD EEG and source localization in order to define the value of this technique in the preoperative assessment of children with refractory partial epilepsy. Source localization using HD EEG requires several steps. The first step, elaboration of the head model, must take into account the heterogeneity of skull bone thickness, persistence of the fontanelles in younger infants, and the unknown conductivities of anatomical structures in children. The second step consists of defining the number of electrodes, which depends on the age and cortical gyration of the brain. Finally, after extraction of meaningful information (interictal or ictal features), the third step consists of defining the specific modalities required in pediatric subjects to resolve the inverse problem to determine source localization.

Benign epilepsy with centrotemporal spikes (BECTS) is the most common idiopathic childhood epilepsy, which is often associated with developmental disorders in children. In the present study, we analyzed resting state EEG spectral changes in the sensor and source spaces in eight BECTS patients compared with nine age-matched controls. Using high-resolution scalp EEG data, we assessed statistical differences in spatial distributions of EEG power spectra and cortical sources of resting state EEG rhythms in five frequency bands: δ (0.5–3.5 Hz), θ (4–8 Hz), α (8.5–13 Hz), β1 (13.5–20 Hz) and β2 (20.5–30 Hz) under the eyes-closed resting state condition. To further investigate the impact of centrotemporal spikes on EEG spectra, we split the EEG data of the patient group into EEG portions with and without spikes. Source localization demonstrated the homogeneity of our population of BECTS patients with a common epileptic zone over the right centrotemporal region. Significant differences in terms of both spectral power and cortical source densities were observed between controls and patients. Patients were characterized by significantly increased relative power in θ, α, β1 and β2 bands in the right centrotemporal areas over the spike zone and in the right temporo-parieto-occipital junction. Furthermore, the relative power in all bands significantly decreased in the bilateral frontal and parieto-occipital areas of patients regardless of the presence or absence of spikes in EEG segments. However, the spectral differences between patients and controls were more pronounced in the presence of spikes. This observation emphasized the impact of benign epilepsy on cortical source power, especially in the right centrotemporal regions. Spectral changes in bilateral frontal and parieto-occipital areas may also suggest alterations in the default mode network in BECTS patients., Highlights • BECTS patients exhibited enhanced θ activity over all cortical regions. • BECTS patients displayed reduced α activity at the occipital regions. • Patients showed increased power in θ, α, β in right temporo-parieto-occipital pole. • EEG spectral changes in BECTS patients indicate dysfunction at the epileptic zone. • EEG spectral changes in BECTS patients may show alteration in default mode network.

Array comparative genomic hybridization (array CGH) has proven its utility in uncovering cryptic rearrangements in patients with X-linked intellectual disability. In 2009, Giorda et al. identified inherited and de novo recurrent Xp11.23p11.22 microduplications in two males and six females from a wide cohort of patients presenting with syndromic intellectual disability. To date, 14 females and 5 males with an overlapping microduplication have been reported in the literature. To further characterize this emerging syndrome, we collected clinical and microarray data from 17 new patients, 10 females, and 7 males. The Xp11.23p11.2 microduplications detected by array CGH ranged in size from 331 Kb to 8.9 Mb. Five patients harbored 4.5 Mb recurrent duplications mediated by non-allelic homologous recombination between segmental duplications and 12 harbored atypical duplications. The chromosomal rearrangement occurred de novo in eight patients and was inherited in six affected males from three families. Patients shared several common major characteristics including moderate to severe intellectual disability, early onset of puberty, language impairment, and age related epileptic syndromes such as West syndrome and focal epilepsy with activation during sleep evolving in some patients to continuous spikes-and-waves during slow sleep. Atypical microduplications allowed us to identify minimal critical regions that might be responsible for specific clinical findings of the syndrome and to suggest possible candidate genes: FTSJ1 and SHROOM4 for intellectual disability along with PQBP1 and SLC35A2 for epilepsy. Xp11.23p11.22 microduplication is a recently-recognized syndrome associated with intellectual disability, epilepsy, and early onset of puberty in females. In this study, we propose several genes that could contribute to the phenotype.

Objectives To better define the physiopathology of Interictal Epileptic Spikes (IES) and specially: (i) the mechanisms that propel neurons to hypersynchronizations, and (ii) the local and distant dynamic changes of neuronal population activities, we performed a time frequency analysis (TFA) of the surrounding activation of the IES. Methods HD EEG (64 and 128 electrodes) of 19 children (10 males; mean age 9.6 years), with refractory partial epilepsy of different aetiology, were analysed. Two types of IES were analyzed: spikes and poly-spike waves. TFA was performed on HD EEG epochs around the peak of IES (± 1000 ms). TFAs were calculated for frequencies between 4 and 50 Hz. Source localization was then performed from averaging spikes on EEG, from hypersynchronization, and from changes in TFA before hypersynchronization. Results Two time-frequency patterns were individualized: one specific for spike, the other specific for poly-spike-wave. TFA also revealed desynchronization around (before and after) hypersynchronization of IES (± 400 ms) in the epileptogenic zone, as already described in BECTS and in epileptic rats. At the lobar level the source localization was more accurate when performed during desynchronization (100%) than when performed during hypersynchronization (90%), and also than when performed on the peak of IES (74%) in the time domain. Discussion TFA with HD EEG in a children population of refractory partial epilepsy indicate complex changes in the dynamics of neuronal networks, not only during, but also before and after IES that is not specific to the type of epilepsy but to the type of IES. This provides new insight in the mechanism that propels neurons to synchronize. Source localization of IES should be performed during desynchronization, suggesting that the pathological activation already spread before the neuronal hypersynchronization of the IES.

Introduction Many questions concerning the mechanisms that drive neurons to hypersynchronize remain unsolved, but synaptic as well as non-synaptic events are likely to be involved. Here Optical Imaging (OI) of the epileptic brain by concomitant electroencephalography (FOS-ECoG/HD-EEG), allow investigating the changes in the cellular environment associated with Interictal Epileptic Spikes (IES). The FOS changes (milliseconds) are related to non-synaptic events neuronal activation while ECoG-HDEEG investigates the synaptic events related to the IES. Methods In 3 patients with frontal epileptic spikes, High-Density EEG (HD-EEG) was acquired with 64 electrodes. In 15 epileptic penicillin rats’ experiments, ECoG signals were acquired with two monopolar electrodes disposed over the somatosensory cortex. FOS were recorded with a frequency-domain spectrophotometer at a sampling rate of 62.5 Hz with 16/2 detectors and 4/2 sources in patients and rats respectively. In order to provide an independent control condition to evaluate the method and the specificity of FOS in IES, the FOS signal in response to electrical stimulation of the median nerve was evaluated in both species. Results In both species median nerve stimulation (mERP) induces similar changes in FOS signal consisted in an increase followed by a decrease in the FOS concomitant to the mERP. In both species, alternating increase–decrease-increase in FOS occurred 200 ms before to 180 ms after the IES peak. This started before any changes in EEG signal. Time–frequency domain ECoG-HD EEG analysis revealed alternating decrease-increase–decrease in the EEG spectral power concomitantly with changes in FOS during IES. The FOS response was weaker with a lower signal-to-noise ratio when recorded on the scalp than when recorded from the cortex.This suggests a tight relationship between (de) synchronization and neuronal volume changes during IES. Conclusion FOS-ECoG/HDEEG analysis revel complex changes surrounding the IES and illustrating the complexity of the underlying mechanisms of IES generation. These changes in the neuronal environment around IES in frontal lobe epilepsy in children and in rats raise new questions about the synaptic and non-synaptic mechanisms that propel the neurons to IES hypersynchronization. Because it unable to evaluate non-invasively the synaptic and non-synaptic compartments, this multiscale multimodal high temporal resolution approach offer the opportunity to thoroughly investigate the pathophysiology of the IES. FOS response was specific to exogenous stimuli or endogenous neuronal activation (IES). The observed responses in epileptic patients were similar to those on epileptic rats using similar acquisition protocol and data analysis processes. This suggests that the mechanisms involved are fairly specific to the epileptic spikes, independently of the species and of the type of epilepsy.

EEG is an important tool for early cerebral evaluation in neonatal hypoxo-ischemic encephalopathy (HIE). The aim of our study was to precise the EEG prognosis value before starting hypothermia and during 72 h hypothermia in neurodevelopment evaluation with at least 2 years clinical follow-up. We analyzed 98 newborns admitted for suspicion of HIE. First EEG was done before 6 h of life, it was surveyed continuously and analyzed twice a day during 72 H hypothermia and in 12 h following rewarming. EEG recordings were characterized according to the French classification. The neurologic outcome was assessed at 24 months. Eighty-four infants completed neurodevelopmental follow-up. 18 of newborns died during the neonatal period. Among the survivors, 64%, 21% and 15% had respectively normal, moderate and severe outcomes. The first EEG before hypothermia do not correlated with the neurodevelopmental outcome. On the other hand, The EEG characteristics between 36 and 60 h of life, correlated strongly with the outcome. Normal or mildly abnormal EEG (minor abnormalities or discontinuous tracing type A) after the first 48 h had 95% positive predictive value EEG for normal or moderate impairment at 2 years (negative predictive value 77%, specificity 91%). Severe EEG abnormalities (discontinuous tracing type B, paroxysmal or inactive tracings) within the first 48 h had respectively 96% and 76% negative and positive value for poor outcomes (severe outcome or death) (sensitivity 91% and specificity 89%).

Background The early identification of preterm infants at high neurological risk is essential. EEG is the only functional tool, which allows evaluating the cerebral maturation during the neonatal period. One of the EEG neuro-biomarker is the length Burst Activity (BA) adjusted to Post-Menstrual Age (PMA). For extremely preterms, studies about the predictive value of EEG are scarce, based on visual analysis in small cohorts. Objectives The objective of our study was to characterize BA in a large cohort of extreme preterms, using an automated burst detection tool develop and optimize in our laboratory, and to correlate BA characteristics with the brain maturation and the neurological outcome. Methods A total number of 86 preterm infants born before 28 weeks GA at Amiens University Hospital were included. Outcome assessment was based on Denver Developmental Screening Test Scale, at 2 years. The first EEG of each infants recording before 30 weeks PMA was analyzed with the automated detection method. Results The mean BA duration was significantly higher for infants with favorable outcome compared to infants with unfavorable outcome. With the PMA, the cerebral maturation of infants with the favorable outcome is characterized by an increase of the mean BA duration associated with a decrease of the number of BA. Conversely, in case of unfavorable evolution, the mean BA duration remains below 10 s despite the increase of PMA. Conclusion Automatic BA tool allow evaluating the brain maturation in extremely preterms and defining objective neurobiomarker of neurodevelopmental outcome.

Objectives Hypoxo-ischemic encephalopathy (HIE) is by far the most frequent etiology in neonatal encephalopathy). It is an important cause of neonatal mortality and long-term neurosensorial and cognitive impairment. Therapeutic hypothermia is nowadays the only therapeutic neuroprotective mean to decrease second state lesions within 6 hours after hypoxo-ischemia with an effect on mortality and morbidity rates as well as on seizures. The aim of our study was to precise EEG criteria in starting hypothermia decision and in prognosis evaluation with at least 2 years clinical follow-up. Methods We analyzed 120 newborns admitted, between January 2013 and February 2015, in the neonatal intensive care for suspicion of HIE. First EEG was done before 6 hours of life, it was surveyed continuously and analyzed twice a day during 72-hour hypothermia and in 12 hours following rewarming. Three grades classification were used according to French EEG classification. EEG characteristics were analyzed for the decision of hypothermia and to determine prognosis in hours following warming and compared to the neurodevelopment evaluation at 2 years old using standardized scales. Results The evolution of infants with initial grades 0 or 1 EEG was characterized by normal or mild neurodevelopment impairment. Infants with initial grade 3 on EEG, without improvement within the first 48 hours were always associated with severe outcome (severe neurological impairment or death). For the other initial grade 3, who improve within the first 48 hours under hypothermia, as well as the initial grade 2, a variable outcome, between normal to severe neurological sequelae, were noted. Conclusion Our results confirmed that Conventional EEG remains the gold standard for hypothermia decision and in prognostic evaluation [1] , [2] . However, prospective longitudinal studies in large cohort are necessary to better clarify grade 2 EEG abnormalities in order to improve the prognosis evaluation; specially background and specific EEG pattern.

The non-invasive multimodal analysis of brain function in the premature babies makes it possible to evaluate the implementation of neural networks involved in various functions such as language. The establishment of neural networks is the result of (1) initial genetic factors that participate in the structural and functional development of networks, (2) endogenous stimuli-independent generators, (3) endogenous stimulus-dependent generators and (4) stimuli-dependant activations. Multimodal analysis, magnetic resonance imaging, optical imaging and high-resolution EEG (HR-EEG) source imaging enable the analysis of these initial premature networks. Thus, as early as 28 weeks gestational age, when the thalamocortical afferents start to connect the cortical plate, when perisylvian structures exhibit certain structural asymmetries, the neural network is able to discriminate voice and phonemes with a neural strategy involving synchronization habituation and mismatch in specific areas, suggesting a strong genetic fingerprint in these initial abilities. Using HR-EEG in premature makes it possible to demonstrate that some endogenous generators such as the theta temporal activities located in the posterior part of the temporal planum are stimuli-independent up to 30-week gestational age and probably participate in the early functional wiring of the perisylvian networks involved in language and communication functions.

Introduction High Density electroencephalography (HD EEG) is the reference non-invasive technique to investigate the dynamics of neuronal networks in Benign Epilepsy with Centro-Temporal Spikes (BECTS). Analysis of local dynamic changes surrounding Interictal Epileptic Spikes (IES) might improve our knowledge of the mechanisms that propel neurons to the hypersynchronization of IES in BECTS. Transient distant changes in the dynamics of neurons populations may also interact with neuronal networks involved in various functions that are impaired in BECTS patients. Methods HD EEG (64 electrodes) of eight well characterized BECTS patients (8 males; mean age: 7.2 years, range: 5–9 years) were analyzed. Unilateral IES were selected in 6 patients. They were bilateral and independent in 2 other patients. This resulted in a total of 10 groups of IES. Time–frequency analysis was performed on HD EEG epochs around the peak of the IES (±1000 ms), including phase-locked and non-phase-locked activities to the IES. The time frequency analyses were calculated for the frequencies between 4 and 200 Hz Results Time–frequency analysis revealed two patterns of dysregulation of the synchronization between neuronal networks preceding and following hypersynchronization of interictal spikes (±400 ms) in the epileptogenic zone. Dysregulation consists of either desynchronization (n = 6) or oscillating synchronization (n = 4) (4–50 Hz) surrounding the IES. The 2 patients with bilateral IES exhibited only local desynchronization whatever the IES considered. Distant desynchronization in low frequencies within the same window occurs simultaneously in bilateral frontal, temporal and occipital areas (n = 7). Conclusion Using time–frequency analysis of HD EEG data in a well-defined population of BECTS, we demonstrated repeated complex changes in the dynamics of neuronal networks not only during, but also, before and after the IES. In the epileptogenic zone, our results found more complex reorganization of the local network than initially thought. In line with previous results obtained at a microscopic or macroscopic level, these changes suggested the variability strategies of neuronal assemblies to raise IES. Distant changes from the epileptogenic zone in desynchronization observed in the same time window suggested interactions between larger embedded networks and opened new avenues about their possible role in the underlying mechanism leading to cognitive deficits.

Objective Although infantile spasms can be caused by a variety of etiologies, the clinical features are stereotypical. The neuronal and vascular mechanisms that contribute to the emergence of infantile spasms are not well understood. Methods We performed a multimodal study by simultaneously recording electroencephalogram and functional Near-infrared spectroscopy in an intentionally heterogeneous population of six children with spasms in series. Results Regardless of the etiology, spasms were accompanied by two phases of hemodynamic changes; an initial change in the cerebral blood volume (simultaneously with each spasm) followed by a neurovascular coupling in all children except for the one with a large porencephalic cyst. Discussion Changes in cerebral blood volume, like the neurovascular coupling, occurred over frontal areas in all patients regardless of any brain damage suggesting a diffuse hemodynamic cortical response. Significance The simultaneous motor activation and changes in cerebral blood volume might result from the involvement of the brainstem. The inconstant neurovascular coupling phase suggests a diffuse activation of the brain likely resulting too from the brainstem involvement that might trigger diffuse changes in cortical excitability.