Full bandwidth electrophysiology of seizures and epileptiform activity enabled by flexible graphene micro-transistor depth neural probes

ABSTRACTMapping the entire frequency bandwidth of neuronal oscillations in the brain is of paramount importance for understanding physiological and pathological states. The ability to record simultaneously infraslow activity (<0.1 Hz) and higher frequencies (0.1-600 Hz) using the same recording electrode would particularly benefit epilepsy research. However, commonly used metal microelectrode technology is not well suited for recording infraslow activity. Here we use flexible graphene depth neural probes (gDNP), consisting of a linear array of graphene microtransistors, to concurrently record infraslow and high frequency neuronal activity in awake rodents. We show that gDNPs can reliably record and map with high spatial resolution seizures, post-ictal spreading depolarisation, and high frequency epileptic activity through cortical laminae to the CA1 layer of the hippocampus in a mouse model of chemically-induced seizures. We demonstrate functionality of chronically implanted devices over 10 weeks by recording with high fidelity spontaneous spike-wave discharges and associated infraslow activity in a rat model of absence epilepsy. Altogether, our work highlights the suitability of this technology for in vivo electrophysiology research, in particular, to examine the contributions of infraslow activity to seizure initiation and termination.

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Chemogenetic Activation of Feed-Forward Inhibitory Parvalbumin-Expressing Interneurons in the Cortico-Thalamocortical Network During Absence Seizures

Frontiers in Cellular Neuroscience ◽

10.3389/fncel.2021.688905 ◽

2021 ◽

Vol 15 ◽

Author(s):

Sandesh Panthi ◽

Beulah Leitch

Keyword(s):

Absence Epilepsy ◽

Designer Drug ◽

Absence Seizure ◽

Absence Seizures ◽

Feed Forward ◽

Video Recordings ◽

Intraperitoneal Dose ◽

Spike Wave Discharges ◽

The Impact

Parvalbumin-expressing (PV+) interneurons are a subset of GABAergic inhibitory interneurons that mediate feed-forward inhibition (FFI) within the cortico-thalamocortical (CTC) network of the brain. The CTC network is a reciprocal loop with connections between cortex and thalamus. FFI PV+ interneurons control the firing of principal excitatory neurons within the CTC network and prevent runaway excitation. Studies have shown that generalized spike-wave discharges (SWDs), the hallmark of absence seizures on electroencephalogram (EEG), originate within the CTC network. In the stargazer mouse model of absence epilepsy, reduced FFI is believed to contribute to absence seizure genesis as there is a specific loss of excitatory α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) at synaptic inputs to PV+ interneurons within the CTC network. However, the degree to which this deficit is directly related to seizure generation has not yet been established. Using chemogenetics and in vivo EEG recording, we recently demonstrated that functional silencing of PV+ interneurons in either the somatosensory cortex (SScortex) or the reticular thalamic nucleus (RTN) is sufficient to generate absence-SWDs. Here, we used the same approach to assess whether activating PV+ FFI interneurons within the CTC network during absence seizures would prevent or reduce seizures. To target these interneurons, mice expressing Cre recombinase in PV+ interneurons (PV-Cre) were bred with mice expressing excitatory Gq-DREADD (hM3Dq-flox) receptors. An intraperitoneal dose of pro-epileptic chemical pentylenetetrazol (PTZ) was used to induce absence seizure. The impact of activation of FFI PV+ interneurons during seizures was tested by focal injection of the “designer drug” clozapine N-oxide (CNO) into either the SScortex or the RTN thalamus. Seizures were assessed in PVCre/Gq-DREADD animals using EEG/video recordings. Overall, DREADD-mediated activation of PV+ interneurons provided anti-epileptic effects against PTZ-induced seizures. CNO activation of FFI either prevented PTZ-induced absence seizures or suppressed their severity. Furthermore, PTZ-induced tonic-clonic seizures were also reduced in severity by activation of FFI PV+ interneurons. In contrast, administration of CNO to non-DREADD wild-type control animals did not afford any protection against PTZ-induced seizures. These data demonstrate that FFI PV+ interneurons within CTC microcircuits could be a potential therapeutic target for anti-absence seizure treatment in some patients.

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Low-Calcium Epileptiform Activity in the Hippocampus In Vivo

Journal of Neurophysiology ◽

10.1152/jn.00241.2003 ◽

2003 ◽

Vol 90 (4) ◽

pp. 2253-2260 ◽

Cited By ~ 33

Author(s):

Zhouyan Feng ◽

Dominique M. Durand

Keyword(s):

Synaptic Transmission ◽

Epileptiform Activity ◽

Brain Slices ◽

Early Period ◽

Epileptic Activity ◽

Slow Waves ◽

Stratum Radiatum ◽

Low Calcium

It has been clearly established that nonsynaptic interactions are sufficient for generating epileptiform activity in brain slices. However, it is not known whether this type of epilepsy model can be generated in vivo. In this paper we investigate low-calcium nonsynaptic epileptiform activity in an intact hippocampus. The calcium chelator EGTA was used to lower [Ca2+]o in the hippocampus of urethane anesthetized rats. Spontaneous and evoked field potentials in CA1 pyramidal stratum and in CA1 stratum radiatum were recorded using four-channel silicon recording probes. Three different types of epileptic activity were observed while synaptic transmission was gradually blocked by a decline in hippocampal [Ca2+]o. A short latency burst, named early-burst, occurred during the early period of EGTA application. Periodic slow-waves and a long latency high-frequency burst, named late-burst, were seen after synaptic transmission was mostly blocked. Therefore these activities appear to be associated with nonsynaptic mechanisms. Moreover, the slow-waves were similar in appearance to the depolarization potential shifts in vitro with low calcium. In addition, excitatory postsynaptic amino acid antagonists could not eliminate the development of slow-waves and late-bursts. The slow-waves and late-bursts were morphologically similar to electrographic seizure activity seen in patients with temporal lobe epilepsy. These results clearly show that epileptic activity can be generated in vivo in the absence of synaptic transmission. This type of low-calcium nonsynaptic epilepsy model in an intact hippocampus could play an important role in revealing additional mechanisms of epilepsy disorders and in developing novel anti-convulsant drugs.

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Decrease in Synaptic Transmission Can Reverse the Propagation Direction of Epileptiform Activity in Hippocampus In Vivo

Journal of Neurophysiology ◽

10.1152/jn.00593.2004 ◽

2005 ◽

Vol 93 (3) ◽

pp. 1158-1164 ◽

Cited By ~ 7

Author(s):

Zhouyan Feng ◽

Dominique M. Durand

Keyword(s):

Synaptic Transmission ◽

Epileptiform Activity ◽

Epileptic Activity ◽

Propagation Direction ◽

Synaptic Activity ◽

Multiple Channel ◽

Ca1 Region ◽

Partial Suppression

Most types of epileptiform activity with synaptic transmission have been shown to propagate from the CA3 to CA1 region in hippocampus. However, nonsynaptic epileptiform activity induced in vitro is known to propagate slowly from the caudal end of CA1 toward CA2/CA3. Understanding the propagation modes of epileptiform activity, and their causality is important to revealing the underlying mechanisms of epilepsy and developing new treatments. In this paper, the effect of the synaptic transmission suppression on the propagation of epilepsy in vivo was investigated by using multiple-channel recording probes in CA1. Nonsynaptic epileptiform activity was induced by calcium chelator EGTA with varied concentrations of potassium. For comparison, disinhibition synaptic epileptiform activity was induced by picrotoxin (PTX) with or without partial suppression of excitatory synaptic transmission. The propagation velocity was calculated by measuring the time delay between two electrodes separated by a known distance. The results show that in vivo nonsynaptic epileptiform activity propagates with a direction and velocity comparable to those observed in in vitro preparations. The direction of propagation for nonsynaptic activity is reversed from the PTX-induced synaptic activity. A reversal in propagation direction and change in velocity were also observed dynamically during the process of synaptic transmission suppression. Even a partial suppression of synaptic transmission was sufficient to significantly change the propagation direction and velocity of epileptiform activity. These results suggest the possibility that the measurement of propagation can provide important information about the synaptic mechanism underlying epileptic activity.

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Magnesium Inhibits Arterial Thrombi after Vascular Injury in Rat: In Vivo Impairment of Coagulation

Thrombosis and Haemostasis ◽

10.1055/s-0037-1616064 ◽

2001 ◽

Vol 86 (11) ◽

pp. 1292-1295 ◽

Cited By ~ 13

Author(s):

Luigi Sironi ◽

Luca Tedeschi ◽

Anna Maria Calvio ◽

Susanna Colli ◽

Elena Tremoli ◽

...

Keyword(s):

High Frequency ◽

Blood Clotting ◽

Magnesium Deficiency ◽

Ex Vivo ◽

Thrombus Formation ◽

Clotting Time ◽

Chemically Induced ◽

In Vivo Effects ◽

Blood Clotting Time

SummaryMagnesium deficiency is associated with a high frequency of cardiac arrhythmia, hypertension and sudden ischemic death. We investigated the in vivo effects of intravenous magnesium administration in a rat model of chemically induced (FeCl3) carotid thrombosis. The infusion of magnesium sulfate (MgSO4) before the topical application of FeCl3 prevented thrombus formation at concentrations of 0.3 M and 0.6 M, and delayed it even at 0.15 M. Similar results were obtained with MgCl2. The infusion of MgSO4 0.6 M seven minutes after FeCl3 application delayed but did not prevent thrombus formation. MgSO4 slightly reduced platelet aggregation ex vivo without affecting plasma clotting tests, but in vivo blood clotting time was markedly prolonged (tail transection method), thus indicating profoundly impaired coagulation. These data provide a rationale for the use of magnesium as an anti-thrombotic agent, but its pharmacological effect critically depends on the timing of administration.

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Enhancement of Ketone Supplements-Evoked Effect on Absence Epileptic Activity by Co-Administration of Uridine in Wistar Albino Glaxo Rijswijk Rats

Nutrients ◽

10.3390/nu13010234 ◽

2021 ◽

Vol 13 (1) ◽

pp. 234

Author(s):

Brigitta Brunner ◽

Enikő Rauch ◽

Csilla Ari ◽

Dominic P. D’Agostino ◽

Zsolt Kovács

Keyword(s):

Effective Dose ◽

Medium Chain Triglyceride ◽

Epileptic Activity ◽

Absence Epilepsy ◽

A2a Receptor ◽

Spike Wave Discharges ◽

Sch 58261 ◽

Adenosine A2a Receptor Antagonist ◽

Beta Hydroxybutyrate ◽

Adenosine A2a

Both uridine and exogenous ketone supplements decreased the number of spike-wave discharges (SWDs) in a rat model of human absence epilepsy Wistar Albino Glaxo/Rijswijk (WAG/Rij) rats. It has been suggested that alleviating influence of both uridine and ketone supplements on absence epileptic activity may be modulated by A1 type adenosine receptors (A1Rs). The first aim was to determine whether intraperitoneal (i.p.) administration of a specific A1R antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX; 0.2 mg/kg) and a selective adenosine A2A receptor antagonist (7-(2-phenylethyl)-5-amino-2-(2-furyl)-pyrazolo-[4,3-e]-1,2,4-triazolo [1,5-c]pyrimidine) (SCH 58261; 0.5 mg/kg) have a modulatory influence on i.p. 1000 mg/kg uridine-evoked effects on SWD number in WAG/Rij rats. The second aim was to assess efficacy of a sub-effective dose of uridine (i.p. 250 mg/kg) combined with beta-hydroxybutyrate salt + medium chain triglyceride (KSMCT; 2.5 g/kg, gavage) on absence epilepsy. DPCPX completely abolished the i.p. 1000 mg/kg uridine-evoked alleviating effect on SWD number whereas SCH 58261 was ineffective, confirming the A1R mechanism. Moreover, the sub-effective dose of uridine markedly enhanced the effect of KSMCT (2.5 g/kg, gavage) on absence epileptic activity. These results demonstrate the anti-epilepsy benefits of co-administrating uridine and exogenous ketone supplements as a means to treat absence epilepsy.

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Cerebellar Contribution to Absence Epilepsy

10.1101/2020.11.10.376004 ◽

2020 ◽

Author(s):

Leonid S. Godlevsky ◽

Oleh R. Pinyazhko ◽

Olesya B. Poshyvak

Keyword(s):

Epileptic Activity ◽

Absence Epilepsy ◽

Absence Seizure ◽

Imaging Data ◽

Optogenetic Stimulation ◽

Different Types ◽

Spike Wave Discharges ◽

Deep Brain ◽

Spike Wave

ABSTRACTThe new aggregate data analyses revealed the earlier missing role played by the cerebellum long-term electrical stimulation in the absence epilepsy. Neurophysiologic data gained by authors favor that cerebellar serial deep brain stimulation (DBS) (100 Hz) causes the transformation of penicillin-induced cortical focal discharges into prolonged 3,5-3,75 sec oscillations resembling spike-wave discharges (SWD) in cats. Such SWDs were not organized in the form of bursts and persisted continuously after stimulation. Therefore the appearance of prolonged periods of SWD is regarded as a tonic cerebellar influence upon pacemaker of SWD and might be caused by the long-lasting DBS-induced increase of GABA-ergic extrasynaptic inhibition in forebrain networks. At the same time, cerebellar DBS high-frequency (100 Hz) suppressed bursts of SWD observed during the phase of stimulation. Different types of cerebellar DBS upon epileptic activity emphasized the absence seizure facilitation discussed with the reviewed data on optogenetic stimulation, neuronal activity of cerebellar structures, and functional magnetic resonance imaging data.

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Age-Dependent Increase of Absence Seizures and Intrinsic Frequency Dynamics of Sleep Spindles in Rats

Neuroscience Journal ◽

10.1155/2014/370764 ◽

2014 ◽

Vol 2014 ◽

pp. 1-6 ◽

Cited By ~ 9

Author(s):

Evgenia Sitnikova ◽

Alexander E. Hramov ◽

Vadim Grubov ◽

Alexey A. Koronovsky

Keyword(s):

Neurological Diseases ◽

Epileptic Activity ◽

Absence Epilepsy ◽

Sleep Spindles ◽

Intrinsic Frequency ◽

Time Frequency ◽

Age Dependent ◽

Spike Wave Discharges ◽

Epileptic Spike ◽

Spike Wave

The risk of neurological diseases increases with age. In WAG/Rij rat model of absence epilepsy, the incidence of epileptic spike-wave discharges is known to be elevated with age. Considering close relationship between epileptic spike-wave discharges and physiologic sleep spindles, it was assumed that age-dependent increase of epileptic activity may affect time-frequency characteristics of sleep spindles. In order to examine this hypothesis, electroencephalograms (EEG) were recorded in WAG/Rij rats successively at the ages 5, 7, and 9 months. Spike-wave discharges and sleep spindles were detected in frontal EEG channel. Sleep spindles were identified automatically using wavelet-based algorithm. Instantaneous (localized in time) frequency of sleep spindles was determined using continuous wavelet transform of EEG signal, and intraspindle frequency dynamics were further examined. It was found that in 5-months-old rats epileptic activity has not fully developed (preclinical stage) and sleep spindles demonstrated an increase of instantaneous frequency from beginning to the end. At the age of 7 and 9 months, when animals developed matured and longer epileptic discharges (symptomatic stage), their sleep spindles did not display changes of intrinsic frequency. The present data suggest that age-dependent increase of epileptic activity in WAG/Rij rats affects intrinsic dynamics of sleep spindle frequency.

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Critical Role of Astrocytic Polyamine and GABA Metabolism in Epileptogenesis

Frontiers in Cellular Neuroscience ◽

10.3389/fncel.2021.787319 ◽

2022 ◽

Vol 15 ◽

Author(s):

Zsolt Kovács ◽

Serguei N. Skatchkov ◽

Rüdiger W. Veh ◽

Zsolt Szabó ◽

Krisztina Németh ◽

...

Keyword(s):

Epileptiform Activity ◽

Critical Role ◽

Gaba Release ◽

Surface Expression ◽

Absence Epilepsy ◽

Kainate Receptors ◽

Polyamine Metabolism ◽

Major Pathway

Accumulating evidence indicate that astrocytes are essential players of the excitatory and inhibitory signaling during normal and epileptiform activity via uptake and release of gliotransmitters, ions, and other substances. Polyamines can be regarded as gliotransmitters since they are almost exclusively stored in astrocytes and can be released by various mechanisms. The polyamine putrescine (PUT) is utilized to synthesize GABA, which can also be released from astrocytes and provide tonic inhibition on neurons. The polyamine spermine (SPM), synthesized form PUT through spermidine (SPD), is known to unblock astrocytic Cx43 gap junction channels and therefore facilitate astrocytic synchronization. In addition, SPM released from astrocytes may also modulate neuronal NMDA, AMPA, and kainate receptors. As a consequence, astrocytic polyamines possess the capability to significantly modulate epileptiform activity. In this study, we investigated different steps in polyamine metabolism and coupled GABA release to assess their potential to control seizure generation and maintenance in two different epilepsy models: the low-[Mg2+] model of temporal lobe epilepsy in vitro and in the WAG/Rij rat model of absence epilepsy in vivo. We show that SPM is a gliotransmitter that is released from astrocytes and significantly contributes to network excitation. Importantly, we found that inhibition of SPD synthesis completely prevented seizure generation in WAG/Rij rats. We hypothesize that this antiepileptic effect is attributed to the subsequent enhancement of PUT to GABA conversion in astrocytes, leading to GABA release through GAT-2/3 transporters. This interpretation is supported by the observation that antiepileptic potential of the Food and Drug Administration (FDA)-approved drug levetiracetam can be diminished by specifically blocking astrocytic GAT-2/3 with SNAP-5114, suggesting that levetiracetam exerts its effect by increasing surface expression of GAT-2/3. Our findings conclusively suggest that the major pathway through which astrocytic polyamines contribute to epileptiform activity is the production of GABA. Modulation of astrocytic polyamine levels, therefore, may serve for a more effective antiepileptic drug development in the future.

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Activity of the Lateral Hypothalamus during Genetically Determined Absence Seizures

International Journal of Molecular Sciences ◽

10.3390/ijms22179466 ◽

2021 ◽

Vol 22 (17) ◽

pp. 9466

Author(s):

Péter Sere ◽

Nikolett Zsigri ◽

Timea Raffai ◽

Szabina Furdan ◽

Fanni Győri ◽

...

Keyword(s):

Neuronal Activity ◽

Lateral Hypothalamus ◽

Brain Area ◽

State Dependence ◽

Absence Epilepsy ◽

Absence Seizures ◽

Spike Wave Discharges ◽

Genetically Determined

(1) Background: Absence seizures (ASs) are sudden, transient lapses of consciousness associated with lack of voluntary movements and generalized 2.5–4 Hz spike-wave discharges (SWDs) in the EEG. In addition to the thalamocortical system, where these pathological oscillations are generated, multiple neuronal circuits have been involved in their modulation and associated comorbidities including the serotonergic system. Neuronal activity in one of the major synaptic input structures to the brainstem dorsal raphé nucleus (DRN), the lateral hypothalamus (LH), has not been characterized. (2) Methods: We used viral tract tracing and optogenetics combined with in vitro and in vivo electrophysiology to assess the involvement of the LH in absence epilepsy in a genetic rodent model. (3) Results: We found that a substantial fraction of LH neurons project to the DRN of which a minority is GABAergic. The LH to DRN projection can lead to monosynaptic iGluR mediated excitation in DRN 5-HT neurons. Neuronal activity in the LH is coupled to SWDs. (4) Conclusions: Our results indicate that a brain area involved in the regulation of autonomic functions and heavily innervating the RN is involved in ASs. The decreased activity of LH neurons during SWDs could lead to both a decreased excitation and disinhibition in the DRN. These results support a long-range subcortical regulation of serotonergic neuromodulation during ASs and further our understanding of the state-dependence of these seizures and some of their associated comorbidities.

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The Effect of Anti-seizure Medications on the Propagation of Epileptic Activity: A Review

Frontiers in Neurology ◽

10.3389/fneur.2021.674182 ◽

2021 ◽

Vol 12 ◽

Author(s):

Mohamed Khateb ◽

Noam Bosak ◽

Moshe Herskovitz

Keyword(s):

Epileptiform Activity ◽

Clinical Importance ◽

Brain Structures ◽

Epileptic Activity ◽

Point Of View ◽

Interesting Phenomenon ◽

Poor Neurological Outcome ◽

Seizure Propagation

The propagation of epileptiform events is a highly interesting phenomenon from the pathophysiological point of view, as it involves several mechanisms of recruitment of neural networks. Extensive in vivo and in vitro research has been performed, suggesting that multiple networks as well as cellular candidate mechanisms govern this process, including the co-existence of wave propagation, coupled oscillator dynamics, and more. The clinical importance of seizure propagation stems mainly from the fact that the epileptic manifestations cannot be attributed solely to the activity in the seizure focus itself, but rather to the propagation of epileptic activity to other brain structures. Propagation, especially when causing secondary generalizations, poses a risk to patients due to recurrent falls, traumatic injuries, and poor neurological outcome. Anti-seizure medications (ASMs) affect propagation in diverse ways and with different potencies. Importantly, for drug-resistant patients, targeting seizure propagation may improve the quality of life even without a major reduction in simple focal events. Motivated by the extensive impact of this phenomenon, we sought to review the literature regarding the propagation of epileptic activity and specifically the effect of commonly used ASMs on it. Based on this body of knowledge, we propose a novel classification of ASMs into three main categories: major, minor, and intermediate efficacy in reducing the propagation of epileptiform activity.

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