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Slow waves are a distinguishing feature of non-rapid-eye-movement (NREM) sleep, an evolutionarily conserved process critical for brain function. Non-human studies suggest that the claustrum, a small subcortical nucleus, coordinates slow waves. We show that, in contrast to neurons from other brain regions, claustrum neurons in the human brain increase their spiking activity and track slow waves during NREM sleep, suggesting that the claustrum plays a role in coordinating human sleep architecture., (© 2024. The Author(s).)

Objective: Medically refractory epilepsy (MRE) often requires resection of the seizure onset zone (SOZ) for effective treatment. However, when the SOZ is in functional cortex (FC), achieving complete and safe resection becomes difficult, due to the seizure network overlap with function. The authors aimed to assess the safety and outcomes of a combined approach involving partial resection combined with focal neuromodulation for FC refractory epilepsy., Methods: The authors performed a retrospective analysis of individuals diagnosed with MRE who underwent surgical intervention from January 2015 to December 2022. Patients whose SOZ was located in FC and were treated with resection combined with simultaneous implantation of a focal neuromodulation device (responsive neurostimulation [RNS] device) with more than 12 months of follow-up data were included. All patients underwent a standard epilepsy preoperative assessment including intracranial electroencephalography and extraoperative stimulation mapping. Resections were performed under general anesthesia, followed by the concurrent implantation of an RNS device., Results: Seven patients (4 males, median age 32.3 years, all right-handed) were included. The median interval from seizure onset to surgery was 17.4 years. The epileptogenic network included sensorimotor areas (cases 2, 3, and 6), visual cortex (case 1), language areas (cases 4 and 7), and the insula (case 5). The median follow-up was 3 years (range 1-5.8 years). No significant changes in neuropsychological tests were reported. One permanent nondisabling planned neurological deficit (left inferior quadrantanopia) was observed. Six patients had stimulation activated at a median of 4.7 months after resection. All patients achieved good seizure outcomes (5 with Engel class I and 2 with Engel class II outcomes)., Conclusions: Maximal safe resection combined with focal neuromodulation presents a promising alternative to stand-alone resections for MRE epileptogenic zones overlapping with functional brain. This combined approach prioritizes the preservation of function while improving seizure outcomes.

Objective: Statistical learning, the fundamental cognitive ability of humans to extract regularities across experiences over time, engages the medial temporal lobe (MTL) in the healthy brain. This leads to the hypothesis that statistical learning (SL) may be impaired in patients with epilepsy (PWE) involving the temporal lobe, and that this impairment could contribute to their varied memory deficits. In turn, studies done in collaboration with PWE, that evaluate the necessity of MTL circuitry through disease and causal perturbations, provide an opportunity to advance basic understanding of SL., Methods: We implemented behavioral testing, volumetric analysis of the MTL substructures, and direct electrical brain stimulation to examine SL across a cohort of 61 PWE and 28 healthy controls., Results: We found that behavioral performance in an SL task was negatively associated with seizure frequency irrespective of seizure origin. The volume of hippocampal subfields CA1 and CA2/3 correlated with SL performance, suggesting a more specific role of the hippocampus. Transient direct electrical stimulation of the hippocampus disrupted SL. Furthermore, the relationship between SL and seizure frequency was selective, as behavioral performance in an episodic memory task was not impacted by seizure frequency., Significance: Overall, these results suggest that SL may be hippocampally dependent and that the SL task could serve as a clinically useful behavioral assay of seizure frequency that may complement existing approaches such as seizure diaries. Simple and short SL tasks may thus provide patient-centered endpoints for evaluating the efficacy of novel treatments in epilepsy., (© 2023 International League Against Epilepsy.)

We encounter the same people, places, and objects in predictable sequences and configurations. Humans efficiently learn these regularities via statistical learning. Importantly, statistical learning creates knowledge not only of specific regularities but also of regularities that apply more generally across related experiences (i.e., across members of a category). Prior evidence for different levels of learning comes from post-exposure behavioral tests, leaving open the question of whether more abstract regularities are detected online during initial exposure. We address this question by measuring neural entrainment in intracranial recordings. Neurosurgical patients viewed a stream of photographs with regularities at one of two levels: In the exemplar-level structured condition, the same photographs appeared repeatedly in pairs. In the category-level structured condition, the photographs were trial-unique but their categories were paired across repetitions. In a baseline random condition, the same photographs repeated but in a scrambled order. We measured entrainment at the frequency of individual photographs, which was expected in all conditions, but critically also at half that frequency-the rate at which to-be-learned pairs appeared in the two structured (but not random) conditions. Entrainment to both exemplar and category pairs emerged within minutes throughout visual cortex and in frontal and temporal regions. Many electrode contacts were sensitive to only one level of structure, but a significant number encoded both levels. These findings suggest that the brain spontaneously uncovers category-level regularities during statistical learning, providing insight into the brain's unsupervised mechanisms for building flexible and robust knowledge that generalizes across input variation and conceptual hierarchies., (© 2023 Massachusetts Institute of Technology.)

Objective: Super-refractory status epilepticus (SRSE) has high rates of morbidity and mortality. Few published studies have investigated neurostimulation treatment options in the setting of SRSE. This systematic literature review and series of 10 cases investigated the safety and efficacy of implanting and activating the responsive neurostimulation (RNS) system acutely during SRSE and discusses the rationale for lead placement and selection of stimulation parameters., Methods: Through a literature search (of databases and American Epilepsy Society abstracts that were last searched on March 1, 2023) and direct contact with the manufacturer of the RNS system, 10 total cases were identified that utilized RNS acutely during SE (9 SRSE cases and 1 case of refractory SE [RSE]). Nine centers obtained IRB approval for retrospective chart review and completed data collection forms. A tenth case had published data from a case report that were referenced in this study. Data from the collection forms and the published case report were compiled in Excel., Results: All 10 cases presented with focal SE: 9 with SRSE and 1 with RSE. Etiology varied from known lesion (focal cortical dysplasia in 7 cases and recurrent meningioma in 1) to unknown (2 cases, with 1 presenting with new-onset refractory focal SE [NORSE]). Seven of 10 cases exited SRSE after RNS placement and activation, with a time frame ranging from 1 to 27 days. Two patients died of complications due to ongoing SRSE. Another patient's SE never resolved but was subclinical. One of 10 cases had a device-related significant adverse event (trace hemorrhage), which did not require intervention. There was 1 reported recurrence of SE after discharge among the cases in which SRSE resolved up to the defined endpoint., Conclusions: This case series offers preliminary evidence that RNS is a safe and potentially effective treatment option for SRSE in patients with 1-2 well-defined seizure-onset zone(s) who meet the eligibility criteria for RNS. The unique features of RNS offer multiple benefits in the SRSE setting, including real-time electrocorticography to supplement scalp EEG for monitoring SRSE progress and response to treatment, as well as numerous stimulation options. Further research is indicated to investigate the optimal stimulation settings in this unique clinical scenario.

Importance: Mesial temporal lobe epilepsy (MTLE) is the most common focal epilepsy subtype and is often refractory to antiseizure medications. While most patients with MTLE do not have pathogenic germline genetic variants, the contribution of postzygotic (ie, somatic) variants in the brain is unknown., Objective: To test the association between pathogenic somatic variants in the hippocampus and MTLE., Design, Setting, and Participants: This case-control genetic association study analyzed the DNA derived from hippocampal tissue of neurosurgically treated patients with MTLE and age-matched and sex-matched neurotypical controls. Participants treated at level 4 epilepsy centers were enrolled from 1988 through 2019, and clinical data were collected retrospectively. Whole-exome and gene-panel sequencing (each genomic region sequenced more than 500 times on average) were used to identify candidate pathogenic somatic variants. A subset of novel variants was functionally evaluated using cellular and molecular assays. Patients with nonlesional and lesional (mesial temporal sclerosis, focal cortical dysplasia, and low-grade epilepsy-associated tumors) drug-resistant MTLE who underwent anterior medial temporal lobectomy were eligible. All patients with available frozen tissue and appropriate consents were included. Control brain tissue was obtained from neurotypical donors at brain banks. Data were analyzed from June 2020 to August 2022., Exposures: Drug-resistant MTLE., Main Outcomes and Measures: Presence and abundance of pathogenic somatic variants in the hippocampus vs the unaffected temporal neocortex., Results: Of 105 included patients with MTLE, 53 (50.5%) were female, and the median (IQR) age was 32 (26-44) years; of 30 neurotypical controls, 11 (36.7%) were female, and the median (IQR) age was 37 (18-53) years. Eleven pathogenic somatic variants enriched in the hippocampus relative to the unaffected temporal neocortex (median [IQR] variant allele frequency, 1.92 [1.5-2.7] vs 0.3 [0-0.9]; P = .01) were detected in patients with MTLE but not in controls. Ten of these variants were in PTPN11, SOS1, KRAS, BRAF, and NF1, all predicted to constitutively activate Ras/Raf/mitogen-activated protein kinase (MAPK) signaling. Immunohistochemical studies of variant-positive hippocampal tissue demonstrated increased Erk1/2 phosphorylation, indicative of Ras/Raf/MAPK activation, predominantly in glial cells. Molecular assays showed abnormal liquid-liquid phase separation for the PTPN11 variants as a possible dominant gain-of-function mechanism., Conclusions and Relevance: Hippocampal somatic variants, particularly those activating Ras/Raf/MAPK signaling, may contribute to the pathogenesis of sporadic, drug-resistant MTLE. These findings may provide a novel genetic mechanism and highlight new therapeutic targets for this common indication for epilepsy surgery.

Purpose of Review: Technological innovations in the preoperative evaluation, surgical techniques and outcome prediction in epilepsy surgery have grown exponentially over the last decade. This review highlights and emphasizes relevant updates in techniques and diagnostic tools, discussing their context within standard practice at comprehensive epilepsy centres., Recent Findings: High-resolution structural imaging has set an unprecedented opportunity to detect previously unrecognized subtle abnormalities. Machine learning and computer science are impacting the methodologies to analyse presurgical and surgical outcome data, building more accurate prediction models to tailor treatment strategies. Robotic-assisted placement of depth electrodes has increased the safety and ability to sample epileptogenic nodes within deep structures, improving our understanding of the seizure networks in drug-resistant epilepsy. The current available minimally invasive techniques are reasonable surgical alternatives to ablate or disrupt epileptogenic regions, although their sustained efficacy is still an active area of research., Summary: Epilepsy surgery is still underutilized worldwide. Every patient who continues with seizures despite adequate trials of two well selected and tolerated antiseizure medications should be evaluated for surgical candidacy. Collaboration between academic epilepsy centres is of paramount importance to answer long-standing questions in epilepsy surgery regarding the understanding of spatio-temporal dynamics in epileptogenic networks and its impact on surgical outcomes., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

The function of long-term memory is not just to reminisce about the past, but also to make predictions that help us behave appropriately and efficiently in the future. This predictive function of memory provides a new perspective on the classic question from memory research of why we remember some things but not others. If prediction is a key outcome of memory, then the extent to which an item generates a prediction signifies that this information already exists in memory and need not be encoded. We tested this principle using human intracranial EEG as a time-resolved method to quantify prediction in visual cortex during a statistical learning task and link the strength of these predictions to subsequent episodic memory behavior. Epilepsy patients of both sexes viewed rapid streams of scenes, some of which contained regularities that allowed the category of the next scene to be predicted. We verified that statistical learning occurred using neural frequency tagging and measured category prediction with multivariate pattern analysis. Although neural prediction was robust overall, this was driven entirely by predictive items that were subsequently forgotten. Such interference provides a mechanism by which prediction can regulate memory formation to prioritize encoding of information that could help learn new predictive relationships. SIGNIFICANCE STATEMENT When faced with a new experience, we are rarely at a loss for what to do. Rather, because many aspects of the world are stable over time, we rely on past experiences to generate expectations that guide behavior. Here we show that these expectations during a new experience come at the expense of memory for that experience. From intracranial recordings of visual cortex, we decoded what humans expected to see next in a series of photographs based on patterns of neural activity. Photographs that generated strong neural expectations were more likely to be forgotten in a later behavioral memory test. Prioritizing the storage of experiences that currently lead to weak expectations could help improve these expectations in future encounters., (Copyright © 2022 the authors.)

Supplementary motor area (SMA) syndrome is a typically transient condition resulting from damage to the medial premotor cortex. The exact mechanism of recovery remains unknown but is traditionally described as a process involving functional compensation by the contralateral SMA through corpus callosal fibers. The purpose of this case study is to highlight a distinct extracallosal mechanism of functional recovery from an SMA syndrome in a patient with agenesis of the corpus callosum (ACC). We present the clinical presentation and perioperative functional neuroimaging features of a 16-year-old patient with complete ACC who exhibited recovery from an SMA syndrome resulting from surgical resection of a right-sided low-grade glioma. Preoperative fMRI revealed anatomically concordant activation areas during finger and toe tapping tasks bilaterally. Three months after surgery, the patient had fully recovered, and a repeat fMRI revealed shift of the majority of the left toe tapping area from the expected contralateral hemisphere to the ipsilateral left paracentral lobule and SMA. The fMRI signal remodeling observed in this acallosal patient suggests that within-hemisphere plasticity of the healthy hemisphere may constitute an alternative critical process in SMA syndrome resolution and challenges the traditional view that transcallosal fibers are necessary for functional recovery., (Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)

Objective: To evaluate the role of intracranial electroencephalography monitoring in diagnosing and directing the appropriate therapy for MRI-negative epilepsy and to present the surgical outcomes of patients following treatment., Methods: Retrospective chart review between 2015-2021 at a single institution identified 48 patients with no lesion on MRI, who received surgical intervention for their epilepsy. The outcomes assessed were the surgical treatment performed and the International League Against Epilepsy seizure outcomes at 1 year of follow-up., Results: Eleven patients underwent surgery without invasive monitoring, including vagus nerve stimulation (10%), deep brain stimulation (8%), laser interstitial thermal therapy (2%), and callosotomy (2%). The remaining 37 patients received invasive monitoring followed by resection (35%), responsive neurostimulation (21%), and deep brain stimulation (15%) or no treatment (6%). At 1 year postoperatively, 39% were Class 1-2, 36% were Class 3-4 and 24% were Class 5. More patients with Class 1-2 or 3-4 outcomes underwent invasive monitoring (100% and 83% respectively) compared with those with poor outcomes (25%, P < .001). Patients with Class 1-2 outcomes more commonly underwent resection or responsive neurostimulation: 69% and 31%, respectively (P < .001)., Significance: The optimal management of MRI-negative focal epilepsy may involve invasive monitoring followed by resection or responsive neurostimulation in most cases, as these treatments were associated with the best seizure outcomes in our cohort. Unless multifocal onset is clear from the noninvasive evaluation, invasive monitoring is preferred before pursuing deep brain stimulation or vagal nerve stimulation directly., (© 2022 The Authors. Epilepsia Open published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.)

Objective: Temporal lobe encephaloceles (TLENs) are a significant cause of medically refractory epilepsy, but there is little consensus regarding their workup and treatment. This study characterizes these lesions and their role in seizures and aims to standardize preoperative evaluation and surgical management., Methods: Patients with TLEN who had undergone resective epilepsy surgery from December 2015 to August 2020 at a single institution were included in the study. Medical records were reviewed for each patient to collect relevant seizure workup information including demographics, radiological findings, surgical data, and neuropsychological evaluation., Results: For patients who presented to the authors' program with suspected medically intractable temporal lobe epilepsy (219 patients), TLEN was considered to be the epileptogenic focus in 5.5%. Ten patients with TLEN had undergone resection and were included in this study. Concordance between ictal scalp electroencephalography (EEG) lateralization and TLEN was found in 9/10 patients (90%), and 4/10 patients (40%) had signs suggestive of idiopathic intracranial hypertension (IIH). Surgical outcome was reported in patients with at least 12 months of follow-up (9/10). Patients with scalp EEG findings concordant with the TLEN side had a good outcome (Engel class I: 7 patients, class II: 1 patient). One patient with discordant EEG findings had a bad outcome (Engel class III). No significant neuropsychological deficits were observed after the surgery., Conclusions: TLENs are epileptogenic lesions that should be screened for in patients with medically refractory epilepsy who have signs of IIH and no other lesions on MRI. Restricted resection is safe and effective in patients with scalp EEG findings concordant with TLEN.

The objective of this study was to monitor the extracellular brain chemistry dynamics at baseline and in relation to spontaneous seizures in human patients with refractory epilepsy. Thirty patients with drug-resistant focal epilepsy underwent intracranial electroencephalography and concurrent brain microdialysis for up to 8 continuous days. Extracellular brain glutamate, glutamine, and the branched-chain amino acids (BCAAs) valine, leucine, and isoleucine were quantified in the dialysis samples by liquid chromatography-tandem mass spectrometry. Extracellular BCAAs and glutamate were chronically elevated at baseline by approximately 1.5-3-fold in brain regions of seizure onset and propagation versus regions not involved by seizures. Moreover, isoleucine increased significantly above baseline as early as 3 h before a spontaneous seizure. BCAAs play important roles in glutamatergic neurotransmission, mitochondrial function, neurodegeneration, and mammalian target of rapamycin signaling. Because all of these processes have been implicated in epilepsy, the results suggest a novel role of BCAAs in the pathogenesis of spontaneous seizures., (© 2021 International League Against Epilepsy.)

Mural cells (smooth muscle cells and pericytes) are integral components of brain blood vessels that play important roles in vascular formation, blood-brain barrier maintenance, and regulation of regional cerebral blood flow (rCBF). These cells are implicated in conditions ranging from developmental vascular disorders to age-related neurodegenerative diseases. Here we present complementary tools for cell labeling with transgenic mice and organic dyes that allow high-resolution intravital imaging of the different mural cell subtypes. We also provide detailed methodologies for imaging of spontaneous and neural activity-evoked calcium transients in mural cells. In addition, we describe strategies for single- and two-photon optogenetics that allow manipulation of the activity of individual and small clusters of mural cells. Together with measurements of diameter and flow in individual brain microvessels, calcium imaging and optogenetics allow the investigation of pericyte and smooth muscle cell physiology and their role in regulating rCBF. We also demonstrate the utility of these tools to investigate mural cells in the context of Alzheimer's disease and cerebral ischemia mouse models. Thus, these methods can be used to reveal the functional and structural heterogeneity of mural cells in vivo, and allow detailed cellular studies of the normal function and pathophysiology of mural cells in a variety of disease models. The implementation of this protocol can take from several hours to days depending on the intended applications.

Cell death is prevalent throughout life; however, the coordinated interactions and roles of phagocytes during corpse removal in the live brain are poorly understood. We developed photochemical and viral methodologies to induce death in single cells and combined this with intravital optical imaging. This approach allowed us to track multicellular phagocytic interactions with precise spatiotemporal resolution. Astrocytes and microglia engaged with dying neurons in an orchestrated and synchronized fashion. Each glial cell played specialized roles: Astrocyte processes rapidly polarized and engulfed numerous small dendritic apoptotic bodies, while microglia migrated and engulfed the soma and apical dendrites. The relative involvement and phagocytic specialization of each glial cell was plastic and controlled by the receptor tyrosine kinase Mertk . In aging, there was a marked delay in apoptotic cell removal. Thus, a precisely orchestrated response and cross-talk between glial cells during corpse removal may be critical for maintaining brain homeostasis., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

Lipid-processing mechanisms during demyelination are poorly understood. In this issue of Neuron,Nugent et al. (2020) show by cell-specific lipidomics that Trem2 deficiency leads to cholesterol ester (CE) overload in microglia. This is mediated by misregulation of lipid metabolism genes and is rescued by modulating CE synthesis or efflux., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Introduction: Despite advancements in medical and surgical therapies, clinical outcomes of aneurysmal subarachnoid hemorrhage (aSAH) continue to be poor. Currently, aSAH pathophysiology remains poorly understood. No aSAH biomarkers are commonly used in the clinical setting. This exploratory study used metabolomics profiling to identify global metabolic changes and metabolite predictors of long-term outcome using cerebrospinal fluid (CSF) samples of aSAH patients., Methods and Methods: Gas chromatography time-of-flight mass spectrometry was applied to CSF samples collected from 15 consecutive high-grade aSAH patients (modified Fisher grade 3 or 4). Collected CSF samples were analyzed at two time points (admission and the anticipated vasospasm timeframe). Metabolite levels at both time points were compared and correlated with vasospasm status and Glasgow Outcome Scale (GOS) of patients at 1 year post-aSAH. Significance level was defined as p < 0.05 with false discovery rate correction for multiple comparisons., Results: Of 97 metabolites identified, 16 metabolites, primarily free amino acids, significantly changed between the two time points. These changes were magnified in modified Fisher grade 4 compared with grade 3. Six metabolites (2-hydroxyglutarate, tryptophan, glycine, proline, isoleucine, and alanine) correlated with GOS at 1 year post-aSAH independent of vasospasm status. When predicting patients who had low disability (GOS 5 vs. GOS ≤4), 2-hydroxyglutarate had a sensitivity and specificity of 0.89 and 0.83 respectively., Conclusions: Our preliminary study suggests that specific metabolite changes occur in the brain during the course of aSAH and that quantification of specific CSF metabolites may be used to predict long-term outcome in patients with aSAH. This is the first study to implicate 2-hydroxyglutarate, a known marker of tissue hypoxia, in aSAH pathogenesis.

OBJECTIVE Following an initial response of brain metastases to Gamma Knife radiosurgery, regrowth of the enhancing lesion as detected on MRI may represent either radiation necrosis (a treatment-related inflammatory change) or recurrent tumor. Differentiation of radiation necrosis from tumor is vital for management decision making but remains difficult by imaging alone. In this study, gas chromatography with time-of-flight mass spectrometry (GC-TOF) was used to identify differential metabolite profiles of the 2 tissue types obtained by surgical biopsy to find potential targets for noninvasive imaging. METHODS Specimens of pure radiation necrosis and pure tumor obtained from patient brain biopsies were flash-frozen and validated histologically. These formalin-free tissue samples were then analyzed using GC-TOF. The metabolite profiles of radiation necrosis and tumor samples were compared using multivariate and univariate statistical analysis. Statistical significance was defined as p ≤ 0.05. RESULTS For the metabolic profiling, GC-TOF was performed on 7 samples of radiation necrosis and 7 samples of tumor. Of the 141 metabolites identified, 17 (12.1%) were found to be statistically significantly different between comparison groups. Of these metabolites, 6 were increased in tumor, and 11 were increased in radiation necrosis. An unsupervised hierarchical clustering analysis found that tumor had elevated levels of metabolites associated with energy metabolism, whereas radiation necrosis had elevated levels of metabolites that were fatty acids and antioxidants/cofactors. CONCLUSIONS To the authors' knowledge, this is the first tissue-based metabolomics study of radiation necrosis and tumor. Radiation necrosis and recurrent tumor following Gamma Knife radiosurgery for brain metastases have unique metabolite profiles that may be targeted in the future to develop noninvasive metabolic imaging techniques.

Pericytes and smooth muscle cells are integral components of the brain microvasculature. However, no techniques exist to unambiguously identify these cell types, greatly limiting their investigation in vivo. Here we show that the fluorescent Nissl dye NeuroTrace 500/525 labels brain pericytes with specificity, allowing high-resolution optical imaging in the live mouse. We demonstrate that capillary pericytes are a population of mural cells with distinct morphological, molecular and functional features that do not overlap with precapillary or arteriolar smooth muscle actin-expressing cells. The remarkable specificity for dye uptake suggests that pericytes have molecular transport mechanisms not present in other brain cells. We demonstrate feasibility of longitudinal pericyte imaging during microvascular development and aging and in models of brain ischemia and Alzheimer's disease. The ability to easily label pericytes in any mouse model opens the possibility of a broad range of investigations of mural cells in vascular development, neurovascular coupling and neuropathology.

A major bottleneck limiting understanding of mechanisms and consequences of cell death in complex organisms is the inability to induce and visualize this process with spatial and temporal precision in living animals. Here we report a technique termed two-photon chemical apoptotic targeted ablation (2Phatal) that uses focal illumination with a femtosecond-pulsed laser to bleach a nucleic acid-binding dye causing dose-dependent apoptosis of individual cells without collateral damage. Using 2Phatal, we achieve precise ablation of distinct populations of neurons, glia and pericytes in the mouse brain and in zebrafish. When combined with organelle-targeted fluorescent proteins and biosensors, we uncover previously unrecognized cell-type differences in patterns of apoptosis and associated dynamics of ribosomal disassembly, calcium overload and mitochondrial fission. 2Phatal provides a powerful and rapidly adoptable platform to investigate in vivo functional consequences and neural plasticity following cell death as well as apoptosis, cell clearance and tissue remodelling in diverse organs and species.

Mesial temporal lobe epilepsy (MTLE) is one of the most common forms of drug-resistant, localization-related epilepsies in humans. One potential therapeutic target is the brain glutamine-glutamate-GABA metabolic pathway, which is perturbed in patients with MTLE. Loss of glutamine synthetase (GS) in astrocytes may be critically involved in this perturbation, which can be modeled by infusing the GS inhibitor methionine sulfoximine (MSO) into the entorhinal-hippocampal area in rats. Because 5-aminovaleric acid (5-AV) has been implicated in modulation of the glutamine-glutamate-GABA metabolic pathway, we hypothesized that 5-AV would alter the expression of seizures in the MSO model of MTLE. Male Sprague Dawley rats (300-330g) were implanted with an Alzet pump placed subcutaneously in the abdominal region to release either 5-AV (0.05mg/mL, n=6) or phosphate buffered saline (PBS, n=6) at a rate of 2.5μl/h over 28days. Five to 7days after surgery, all rats were implanted with an intracranial pump infusing MSO (2.5mg/mL; 0.25μl/h) unilaterally into the hippocampal formation. Following the second surgery, intracranial EEG was measured from the left and right hemispheres above the dorsal hippocampal formations for a continuous period of 21days. The EEG was correlated with simultaneous video recordings to determine the stage of seizures according to a modified Racine scale. Five-AV-treated rats experienced a 3.5 fold reduction in the number of seizures (6.7±1.4seizures/day) than PBS-treated rats (23.2±6.3seizures/day) during the first 2days following MSO pump placement (p<0.005). Both groups showed similar seizure frequency over days 3-21 (~1seizure/day). However, the fraction of the most severe type of seizures (Racine stages 4 and 5) increased over time in the PBS treated group, but not in the 5-AV treated group. Notably, 5-AV treated rats experienced a 2.3 and 2.6 fold lower fraction of stage 4 and 5 seizures than PBS-treated rats during the 2nd and 3rd weeks of MSO treatment respectively (p<0 .05 and p<0.001 respective to week). Five-AV markedly reduces the number of seizures initially and suppresses the development of the most severe type of seizures in the MSO model of MTLE. These results may have implications for the therapeutic use of 5-AV in treating mesial temporal lobe seizures and for our understanding of the chemical pathology of epileptogenesis and MTLE., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Opinion Statement: The devastation caused by acute ischemic strokes is evident in every intensive care unit across the world. Although there is no doubt that progress has been made in treatment, it has been slow to come. With the emergence of new technologies in imaging, thrombolysis and endovascular intervention, the treatment modalities of acute ischemic stroke will enter a new era. In this review, we present the concept of the seven evolutionary phases in the treatment of acute ischemic stroke to date.