Epileptic seizure suppression: A computational approach for identification and control using real data.

Epilepsy affects millions of people worldwide every year and remains an open subject for research. Current development on this field has focused on obtaining computational models to better understand its triggering mechanisms, attain realistic descriptions and study seizure suppression. Controllers have been successfully applied to mitigate epileptiform activity in dynamic models written in state-space notation, whose applicability is, however, restricted to signatures that are accurately described by them. Alternatively, autoregressive modeling (AR), a typical data-driven tool related to system identification (SI), can be directly applied to signals to generate more realistic models, and since it is inherently convertible into state-space representation, it can thus be used for the artificial reconstruction and attenuation of seizures as well. Considering this, the first objective of this work is to propose an SI approach using AR models to describe real epileptiform activity. The second objective is to provide a strategy for reconstructing and mitigating such activity artificially, considering non-hybrid and hybrid controllers - designed from ictal and interictal events, respectively. The results show that AR models of relatively low order represent epileptiform activities fairly well and both controllers are effective in attenuating the undesired activity while simultaneously driving the signal to an interictal condition. These findings may lead to customized models based on each signal, brain region or patient, from which it is possible to better define shape, frequency and duration of external stimuli that are necessary to attenuate seizures.

Reduction of vascular reactivity in rat aortas following pilocarpine-induced status epilepticus.

OBJECTIVE: The authors investigated changes in vascular reactivity in rats following pilocarpine-induced status epilepticus. METHOD: Male Wistar rats weighing between 250g and 300g were used. Status epilepticus was induced using 385 mg/kg i.p. pilocarpine. After 40 days the thoracic aorta was dissected and divided into 4 mm rings and the vascular smooth muscle reactivity to phenylephrine was evaluated. RESULTS: Epilepsy decreased the contractile responses of the aortic rings to phenylephrine (0.1 nM-300 mM). To investigate if this reduction was induced by increasing NO production with/or hydrogen peroxide L-NAME and Catalase were used. L-NAME (N-nitro-L arginine methyl ester) increased vascular reactivity but the contractile response to phenylephrine increased in the epileptic group. Catalase administration decreased the contractile responses only in the rings of rats with epilepsy. CONCLUSIONS: Our findings demonstrated for the first time that epilepsy is capable of causing a reduction of vascular reactivity in rat aortas. These results suggest that vascular reactivity reduction is associated with increased production of Nitric Oxide (NO) as an organic attempt to avoid hypertension produced by excessive sympathetic activation.

Reduction of vascular reactivity in rat aortas following pilocarpine-induced status epilepticus

Abstract Objective: The authors investigated changes in vascular reactivity in rats following pilocarpine-induced status epilepticus. Method: Male Wistar rats weighing between 250g and 300g were used. Status epilepticus was induced using 385 mg/kg i.p. pilocarpine. After 40 days the thoracic aorta was dissected and divided into 4 mm rings and the vascular smooth muscle reactivity to phenylephrine was evaluated. Results: Epilepsy decreased the contractile responses of the aortic rings to phenylephrine (0.1 nM-300 mM). To investigate if this reduction was induced by increasing NO production with/or hydrogen peroxide L-NAME and Catalase were used. L-NAME (N-nitro-L arginine methyl ester) increased vascular reactivity but the contractile response to phenylephrine increased in the epileptic group. Catalase administration decreased the contractile responses only in the rings of rats with epilepsy. Conclusions: Our findings demonstrated for the first time that epilepsy is capable of causing a reduction of vascular reactivity in rat aortas. These results suggest that vascular reactivity reduction is associated with increased production of Nitric Oxide (NO) as an organic attempt to avoid hypertension produced by excessive sympathetic activation.

Embodiment of a virtual prosthesis through training using an EMG-based human-machine interface: Case series.

Therapeutic strategies capable of inducing and enhancing prosthesis embodiment are a key point for better adaptation to and acceptance of prosthetic limbs. In this study, we developed a training protocol using an EMG-based human-machine interface (HMI) that was applied in the preprosthetic rehabilitation phase of people with amputation. This is a case series with the objective of evaluating the induction and enhancement of the embodiment of a virtual prosthesis. Six men and a woman with unilateral transfemoral traumatic amputation without previous use of prostheses participated in the study. Participants performed a training protocol with the EMG-based HMI, composed of six sessions held twice a week, each lasting 30 mins. This system consisted of myoelectric control of the movements of a virtual prosthesis immersed in a 3D virtual environment. Additionally, vibrotactile stimuli were provided on the participant's back corresponding to the movements performed. Embodiment was investigated from the following set of measurements: skin conductance response (affective measurement), crossmodal congruency effect (spatial perception measurement), ability to control the virtual prosthesis (motor measurement), and reports before and after the training. The increase in the skin conductance response in conditions where the virtual prosthesis was threatened, recalibration of the peripersonal space perception identified by the crossmodal congruency effect, ability to control the virtual prosthesis, and participant reports consistently showed the induction and enhancement of virtual prosthesis embodiment. Therefore, this protocol using EMG-based HMI was shown to be a viable option to achieve and enhance the embodiment of a virtual prosthetic limb.

Differences in Evolution of Epileptic Seizures and Topographical Distribution of Tissue Damage in Selected Limbic Structures Between Male and Female Rats Submitted to the Pilocarpine Model.

Epidemiological evidence shows that clinical features and comorbidities in temporal lobe epilepsy (TLE) may have different manifestations depending on the sex of patients. However, little is known about how sex-related mechanisms can interfere with the processes underlying the epileptic phenomenon. The findings of this study show that male rats with epilepsy in the pilocarpine model have longer-lasting and more severe epileptic seizures, while female rats have a higher frequency of epileptic seizures and a greater number of seizure clusters. Significant sex-linked pathological changes were also observed: epileptic brains of male and female rats showed differences in mass reduction of 41.8% in the amygdala and 18.2% in the olfactory bulb, while loss of neuronal cells was present in the hippocampus (12.3%), amygdala (18.1%), and olfactory bulb (7.5%). Another important sex-related finding was the changes in non-neuronal cells with increments for the hippocampus (36.1%), amygdala (14.7%), and olfactory bulb (37%). Taken together, our study suggests that these neuropathological changes may underlie the differences in the clinical features of epileptic seizures observed in male and female rats.

Chaotic and stochastic dynamics of epileptiform-like activities in sclerotic hippocampus resected from patients with pharmacoresistant epilepsy.

The types of epileptiform activity occurring in the sclerotic hippocampus with highest incidence are interictal-like events (II) and periodic ictal spiking (PIS). These activities are classified according to their event rates, but it is still unclear if these rate differences are consequences of underlying physiological mechanisms. Identifying new and more specific information related to these two activities may bring insights to a better understanding about the epileptogenic process and new diagnosis. We applied Poincaré map analysis and Recurrence Quantification Analysis (RQA) onto 35 in vitro electrophysiological signals recorded from slices of 12 hippocampal tissues surgically resected from patients with pharmacoresistant temporal lobe epilepsy. These analyzes showed that the II activity is related to chaotic dynamics, whereas the PIS activity is related to deterministic periodic dynamics. Additionally, it indicates that their different rates are consequence of different endogenous dynamics. Finally, by using two computational models we were able to simulate the transition between II and PIS activities. The RQA was applied to different periods of these simulations to compare the recurrences between artificial and real signals, showing that different ranges of regularity-chaoticity can be directly associated with the generation of PIS and II activities.

Do Hippocampal Neurons Really Count for Comorbid Depression in Patients With Mesial Temporal Lobe Epilepsy and Hippocampal Sclerosis? A Histopathological Study.

Depression is the most frequent psychiatric comorbidity seen in mesial temporal lobe epilepsy (MTLE) patients with hippocampal sclerosis (HS). Moreover, the HS is the most frequent pathological hallmark in MTLE-HS. Although there is a well-documented hippocampal volumetric reduction in imaging studies of patients with major depressive disorder, in epilepsy with comorbid depression, the true role of the hippocampus is not entirely understood. This study aimed to verify if patients with unilateral MTLE-HS and the co-occurrence of depression have differences in neuronal density of the hippocampal sectors CA1-CA4. For this purpose, we used a histopathological approach. This was a pioneering study with patients having both clinical disorders. However, we found no difference in hippocampal neuronal density when depression co-occurs in patients with epilepsy. In this series, CA1 had the lowest counting in both groups, and HS ILAE Type 1 was the most prevalent. More studies using histological assessments are needed to clarify the physiopathology of depression in MTLE-HS.

Amazon rainforest rodents (Proechimys) are resistant to post-stroke epilepsy.

There are no clinical interventions to prevent post-injury epilepsy, a common and devastating outcome after brain insults. Epileptogenic events that run from brain injury to epilepsy are poorly understood. Previous studies in our laboratory suggested Proechimys, an exotic Amazonian rodent, as resistant to acquired epilepsy development in post-status epilepticus models. The present comparative study was conducted to assess (1) stroke-related brain responses 24-h and 30 days after cortical photothrombosis and (2) post-stroke epilepsy between Proechimys rodents and Wistar rats, a traditional animal used for laboratory research. Proechimys group showed smaller volume of ischemic infarction and lesser glial activation than Wistar group. In contrast to Wistar rats, post-stroke decreased levels of pro-inflammatory cytokines and increased levels of anti-inflammatory mediators and growth factors were found in Proechimys. Electrophysiological signaling changes assessed by cortical spreading depression, in vitro and in vivo, showed that Wistar's brain is most severely affected by stroke. Chronic electrocorticographic recordings showed that injury did not lead to epilepsy in Proechimys whereas 88% of the Wistar rats developed post-stroke epilepsy. Science gains insights from comparative studies on diverse species. Proechimys rodents proved to be a useful animal model to study antiepileptogenic mechanisms after brain insults and complement conventional animal models.

Granule cell dispersion is associated with hippocampal neuronal cell loss, initial precipitating injury, and other clinical features in mesial temporal lobe epilepsy and hippocampal sclerosis.

PURPOSE: To characterize a 10-year series of patients with mesial temporal lobe epilepsy (MTLE) and unilateral hippocampal sclerosis (HS) and determine the histopathological characteristic of the association between granule cell dispersion (GCD) and hippocampal neuronal loss. METHODS: The study included 108 MTLE/HS patients. Histopathological analyses were performed in NeuN-stained hippocampal sections for HS pattern, neuronal density, dentate gyrus (DG) pathology, and granule cell layer width. Statistical tests investigated the association between DG pathologies and HS patterns, as well as the correlation of DG width with total hippocampal and subfield-specific neuronal densities. RESULTS: Fifty-six patients (51.9%) presented right HS. All the four ILAE HS patterns were represented (90 Type 1, 11 Type 2, 2 Type 3, and 5 no-HS). Sixty-seven patients (62.0%) presented GCD, 39 (36.1%) normal DG, and 2 (1.9%) narrow DG. GCD was associated with initial precipitating injury, higher numbers of monthly focal seizures and lifetime bilateral tonic-clonic seizures, longer epilepsy duration, and older age at surgery. GCD was prevalent in all HS patterns, except for Type 2 (81.8% normal versus 18.2% GCD, p = 0.005). GCD was associated with total hippocampal and subfield-specific neuronal loss, except for CA1. DG width correlated with total hippocampal (r = -0.201, p = 0.037) and CA4 neuronal densities (r = -0.299, p = 0.002). Patients with HS Type 1 had better surgical outcomes, with 51 (61.4%) seizure-free in the first year post-surgery. CONCLUSIONS: This study confirmed that seizure control in MTLE/HS patients submitted to surgical treatment is comparable worldwide. Moreover, histopathological analyses showed an association between GCD and hippocampal neuronal loss, especially in the CA4 subfield.

Challenges in the treatment of a chronic disease: A study of narratives of people with juvenile myoclonic epilepsy.

PURPOSE: The purpose of this study was to explore how people with juvenile myoclonic epilepsy perceive the impact of treatment. METHODS: We conducted 14 interviews of participants with juvenile myoclonic epilepsy recruited with the support of the Brazilian Association of Epilepsy in 2018 in São Paulo. Thematic analysis was carried out by two investigators who independently coded the transcripts and reviewed the coding results to check for agreement. RESULTS: Participants' (n = 14, 8 female) mean age was 31.4 years (SD ± 8.3) and their onset of seizures occurred at mean age 13.4 (SD ± 2.9). The answers to the interview questions revealed the paths of participants through life as they dealt with difficulties and challenges. Three interrelated themes and seven sub-themes emerged from the answers of the participants: seizure control, impact of epilepsy and attitude of others. CONCLUSION: This investigation may be useful in providing insights for the interventions of health providers in caring for people with JME. Themes and sub-themes that emerged from this study are connected to important aspects of treatment that go beyond focusing solely on seizures.

Gut-microbiota-directed strategies to treat epilepsy: clinical and experimental evidence.

A growing appreciation that the intestinal microbiota might exert changes on the central nervous system via the gut-brain has emerged as a new research frontier in neurological disorders. Moreover, new approaches for studying and manipulating the gut microbiome, including metabolomics and faecal microbiota transplantation, have highlighted the tremendous potential that microbes have on neuroinflammation, metabolic, and neuroendocrine signaling pathways. Despite the large proliferation of studies in animal models examining the linkage between microbial disequilibrium and epilepsy, intestinal profiles at a functional level in humans have remained scarce. We reviewed the scientific evidence on gut microbiota's role in epilepsy, both in clinical and experimental studies, to better understand how targeting the gut microbiota could serve as a diagnostic or prognostic research tool. Likewise, translating microbial molecular mechanisms to medical settings could fill the gaps related to alternative therapies for patients with epilepsy, mainly in cases with refractory phenotypes.

Hormonal and biochemical changes in female Proechimys guyannensis, an animal model of resistance to pilocarpine-induced status epilepticus.

The Amazon rodent Proechimys guyannensis is widely studied for hosting various pathogens, though rarely getting sick. Previous studies on male Proechimys have revealed an endogenous resistance to epilepsy. Here, we assess in female Proechimys, whether sex hormones and biochemical aspects can interfere with the induction of status epilepticus (SE). The lithium-pilocarpine ramp-up protocol was used to induce SE, and blood sera were collected at 30 and 90 min after SE, alongside brains, for biochemical, western blot and immunohistochemical analyses. Results from non-ovariectomised (NOVX) Proechimys were compared to ovariectomised (OVX) animals. Data from female Wistars were used as a positive control of SE inductions. SE latency was similar in NOVX, OVX, and female Wistars groups. However, the pilocarpine dose required to induce SE in Proechimys was higher (25- to 50-folds more). Despite a higher dose, Proechimys did not show strong SE like Wistars; they only reached stage 2 of the Racine scale. These data suggest that female Proechimys are resistant to SE induction. Glucose and progesterone levels increased at 30 min and returned to normal at 90 min after SE. A relevant fact because in humans and rodents, SE leads to hypoglycaemia after 30 min of SE and does not return to normal levels in a short time, a typical adverse effect of SE. In OVX animals, a decrease in GABAergic receptors within 90 min of SE may suggest that ovariectomy produces changes in the hippocampus, including a certain vulnerability to seizures. We speculate that progesterone and glucose increases form part of the compensatory mechanisms that provide resistance in Proechimys against SE induction.

Modulation in phase and frequency of neural oscillations during epileptiform activity induced by neonatal Zika virus infection in mice.

Modulation of brain activity is one of the main mechanisms capable of demonstrating the synchronization dynamics of neural oscillations. In epilepsy, modulation is a key concept since seizures essentially result from neural hypersynchronization and hyperexcitability. In this study, we have introduced a time-dependent index based on the Kullback-Leibler divergence to quantify the effects of phase and frequency modulations of neural oscillations in neonatal mice exhibiting epileptiform activity induced by Zika virus (ZIKV) infection. Through this index, we demonstrate that fast oscillations (gamma and beta 2) are the more susceptible modulated rhythms in terms of phase, during seizures, whereas slow waves (delta and theta) mainly undergo changes in frequency. The index also allowed detection of specific patterns associated with the interdependent modulation of phase and frequency in neural activity. Furthermore, by comparing ZIKV modulations with the general computational model Epileptors, we verify different signatures related to the brain rhythms modulation in phase and frequency. These findings instigate new studies on the effects of ZIKV infection on neuronal networks from electrophysiological activities, and how different mechanisms can trigger epilepsy.

Characterization of the estrous cycle in the Amazon spiny rat (Proechimys guyannensis).

Males of Proechimys guyannensis, a rodent living in the Amazon rainforest are studied in biomedical research because of their antiepileptogenic mechanism. Females are usually taken from experimental designs, because of limited data of this sex. This study aimed to characterize the estrous cycle to include females together with males in research in a more balanced approach. The estrous cycle of P. guyannensis based through exfoliative cytology, determination of the vaginal occlusion membrane state, and hormonal analysis. In this study, cytological analyses of vaginal smears were performed for three months, three times a day. The observed length of the estrous cycle was 247 ± 81 h (mean ± SD) with a reproductive phase of 27.08 ± 17.39 h (estrus stage). We observed a frequent presence of both the open and closed states of the vaginal membrane in the estrus stage (fertile period) although only the open stage is a prerequisite for successful copulation. High levels of progesterone and estradiol were detected in proestrus. Levels of follicle-stimulating hormone peaked at the estrus stage. These data will establish the parameters and subsidies to set the grounds for future research either for investigating the biology of this species or to use P. guyannensis in research that previously excluded females. Information regarding female Proechimys is relevant to not only describe the species but also explain the interaction between sex hormones and physiological responses. Moreover, the present results will enhance rigor and reproducibility in preclinical studies. In conclusion, P. guyannensis reproductive cycles can occur spontaneously and cyclically independent of mating stimulation and the high levels of FSH in the estrus stage, suggest that ovulation occurs in the late phase of the estrus.

Endogenous protection against the 6-OHDA model of Parkinson's disease in the Amazonian rodent Proechimys.

BACKGROUND: Proechimys, an epilepsy-resistant rodent from Amazon Rainforest, is a promising alternative animal model for studying neurodegenerative disorders. OBJECTIVES: To evaluate behavioral and immunohistological changes in Proechimys after 6-OHDA-induced model of PD. METHODS: Following unilateral injections of 6-OHDA into striatum, animals were assessed for exploratory behavior using the cylinder test. Brain sections were submitted to immunohistochemistry for tyrosine hydroxylase (TH), glial fibrillary acidic protein (GFAP), and ionized calcium-binding adaptor molecule 1 (Iba-1). RESULTS: We observed normal exploratory behavior during cylinder test in all animals. We could not detect changes in the expression of TH in both striatum and SNc, suggesting that Proechimys is resistant to dopaminergic neuronal degeneration. Glial activation was observed by an increase in Iba-1 expression in both striatum and SNc, and by an increase in GFAP expression in striatum. CONCLUSIONS: Proechimys represents a promising animal model for studying the mechanisms underlying the susceptibility of dopaminergic neurons to degeneration induced by 6-OHDA.

Plasma kallikrein-kinin system contributes to peripheral inflammation in temporal lobe epilepsy.

Temporal lobe epilepsy (TLE) is a chronic disease, characterized by severe and refractory seizures, triggered in the hippocampus and/or amygdala, disrupting the blood-brain barrier. This disruption can sustain, or aggravate, the epileptic condition. The aim of this study was to evaluate the activation of the kallikrein-kinin system in patients with TLE, as it relates to the maintenance of blood-brain barrier. Human hippocampal sclerotic tissues removed after surgery for seizure control, plasma, and serum were used in the following assays: immunostaining for white blood cells in the TLE hippocampus, C-reactive protein in serum, quantification of plasma kallikrein (PKal) and cathepsin B (CatB) activity in serum and plasma, quantification of C1-inhibitor, analysis of high-molecular-weight kininogen (H-kininogen) fragments, and activation of plasma prekallikrein for comparison with healthy controls. Infiltration of white blood cells in the sclerotic hippocampus and a significant increase in the neutrophil/lymphocyte ratio in the blood of TLE patients were observed. High levels of C-reactive protein (TLE = 1.4 ± 0.3 µg/mL), PKal (TLE = 5.4 ± 0.4 U/mL), and CatB (TLE = 4.9 ± 0.4 U/mL) were also evident in the serum of TLE patients comparing to controls. A strong linear correlation was observed between active CatB and PKal in the serum of TLE patients (r = 0.88). High levels of cleaved H-kininogen and free PKal, and low levels of C1-inhibitor (TLE = 188 ± 12 µg/mL) were observed in the serum of TLE patients. Our data demonstrated that the plasma kallikrein-kinin system is activated in patients with TLE. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/.

Behavioral, electrophysiological and neuropathological characteristics of the occurrence of hypertension in pregnant rats.

Pre-eclampsia (PE) affects approximately 2 to 8% of pregnant women, causing blood pressure above 140 × 90 mmHg and proteinuria, normally after the 20th gestation week. If unsuccessfully treated, PE can lead to self-limited seizures (Eclampsia) that could eventually result in death of the mother and her fetus. The present study reports an experimental model of preeclampsia hypertension in pregnant (HP) and non-pregnant (H) Wistar rats by partially clamping one of their renal arteries. Pregnant (P) and non-pregnant (C) controls were provided. Differently from controls (C and P), H and HP animals presented a steady rise in BP two weeks after renal artery clamping. Injection of pentylenetetrazol (PTZ) induced behavioral and electroencephalographic seizures in all groups, which were increased in number, duration, amplitude and power accompanied by decreased latency in HP animals (p < 0.05). Consistent results were obtained in in vitro experimentation. Immunohistochemistry of hippocampus tissue in HP animals showed decreased density of neurons nuclei in CA1, CA3 and Hilus and increased density of astrocytes in CA1, CA3 and gyrus (p < 0.05). The present findings show that the clamping of one renal arteries to 0.15 mm and PTZ administration were able to induce signs similar to human PE in pregnant Wistar rats.

Robust Network Inhibition and Decay of Early-Phase LTP in the Hippocampal CA1 Subfield of the Amazon Rodent Proechimys.

Background: Diverse forms of long-term potentiation (LTP) have been described, but one of the most investigated is encountered in the glutamatergic synapses of the hippocampal cornu Ammonis (CA1) subfield. However, little is known about synaptic plasticity in wildlife populations. Laboratory animals are extremely inbred populations that have been disconnected from their natural environment and so their essential ecological aspects are entirely absent. Proechimys are small rodents from Brazil's Amazon rainforest and their nervous systems have evolved to carry out specific tasks of their unique ecological environment. It has also been shown that long-term memory duration did not persist for 24-h in Proechimys, in contrast to Wistar rats, when both animal species were assessed by the plus-maze discrimination avoidance task and object recognition test. Methods: In this work, different protocols, such as theta burst, single tetanic burst or multiple trains of high frequency stimulation (HFS), were used to induce LTP in hippocampal brain slices of Proechimys and Wistar rats. Results: A protocol-independent fast decay of early-phase LTP at glutamatergic synapses of the CA1 subfield was encountered in Proechimys. Long-term depression (LTD) and baseline paired-pulse facilitation (PPF) were investigated but no differences were found between animal species. Input/output (I/O) relationships suggested lower excitability in Proechimys in comparison to Wistar rats. Bath application of d-(-)-2-amino-5-phosphonopentanoicacid (D-AP5) and CNQX prevented the induction of LTP in both Proechimys and Wistar. However, in marked contrast to Wistar rats, LTP induction was not facilitated by the GABAA antagonist in the Amazon rodents, even higher concentrations failed to facilitate LTP in Proechimys. Next, the effects of GABAA inhibition on spontaneous activity as well as evoked field potentials (FPs) were evaluated in CA1 pyramidal cells. Likewise, much lower activity was detected in Proechimys brain slices in comparison to those of the Wistar rats. Conclusions: These findings suggest a possible high inhibitory tone in the CA1 network mediated by GABAA receptors in the Amazon rodents. Currently, neuroscience research still seeks to reveal molecular pathways that control learning and memory processes, Proechimys may prove useful in identifying such mechanisms in complement to traditional animal models.