The cerebellum and epilepsy

Optogenetics in oral and craniofacial research

Optogenetics combines optics and genetic engineering to control specific gene expression and biological functions and has the advantages of precise spatiotemporal control, noninvasiveness, and high efficiency. Genetically modified photosensory sensors are engineered into proteins to modulate conformational changes with light stimulation. Therefore, optogenetic techniques can provide new insights into oral biological processes at different levels, ranging from the subcellular and cellular levels to neural circuits and behavioral models. Here, we introduce the origins of optogenetics and highlight the recent progress of optogenetic approaches in oral and craniofacial research, focusing on the ability to apply optogenetics to the study of basic scientific neural mechanisms and to establish different oral behavioral test models in vivo (orofacial movement, licking, eating, and drinking), such as channelrhodopsin (ChR), archaerhodopsin (Arch), and halorhodopsin from Natronomonas pharaonis (NpHR). We also review the synergic and antagonistic effects of optogenetics in preclinical studies of trigeminal neuralgia and maxillofacial cellulitis. In addition, optogenetic tools have been used to control the neurogenic differentiation of dental pulp stem cells in translational studies. Although the scope of optogenetic tools is increasing, there are limited large animal experiments and clinical studies in dental research. Potential future directions include exploring therapeutic strategies for addressing loss of taste in patients with coronavirus disease 2019 (COVID-19), studying oral bacterial biofilms, enhancing craniomaxillofacial and periodontal tissue regeneration, and elucidating the possible pathogenesis of dry sockets, xerostomia, and burning mouth syndrome.

Cerebellar atrophy in genetic epileptic encephalopathies: A cohort study and a systematic review

OBJECTIVE

To analyze cerebellar atrophy in genetic epileptic encephalopathies (EEs).

METHODS

This research included a retrospective cohort study conducted from January 2016 to December 2023 and a systematic review on cerebellar atrophy in genetic EEs. Pediatric individuals who were diagnosed with EEs based on electroclinical features, carried causative gene variants, and exhibited cerebellar atrophy were recruited. Electroclinical features, neuroimaging findings, and causative variants of eligible individuals were analyzed.

RESULTS

The cohort study showed 10 of 67 pediatric individuals (10/67; 15 %) who were diagnosed with genetic EEs had cerebellar atrophy; and 6 of the 10 individuals (6/10; 60 %) exhibited cerebellar signs. Diagnostic delay between the detection of cerebellar atrophy and the identification of genetic diagnosis existed in 6 individuals (6/10; 60 %) and the median duration was 4.4 years. A total of 32 genes, including 31 genes from the literature review and a newly identified SCN2A gene in this cohort, were reported associated with cerebellar atrophy in genetic EEs. Twenty-six genes (26/32; 81 %) accounted for cerebellar atrophy associated with other brain anomalies and 6 genes (6/32; 19 %) caused isolated cerebellar atrophy. Twenty-five genes (25/32; 78 %) showed late-onset cerebellar atrophy identified after the age of 1 year old.

CONCLUSION

Cerebellar atrophy is not uncommon in genetic EEs and may serve as an indicator for molecular diagnosis in clinical practice. To shorten the diagnostic delay, follow-up neuroimaging study is crucial because of high rate of clinico-radiological dissociation and late-onset cerebellar atrophy in this patient group.

Intralesional epileptiform activity in a fourth ventricular hamartoma associated with epileptic hemifacial spasm in a toddler: illustrative case

BACKGROUND

Focal epilepsy caused by a posterior fossa lesion is a rare phenomenon. In these cases, seizure onset typically occurs during the first few months of life, with episodes of epileptic hemifacial spasms and abnormal eye movements. Patients often present with drug-resistant epilepsy and often require resection for the best chance of seizure freedom.

OBSERVATIONS

The authors present the case of a 19-month-old male with intractable epileptic hemifacial spasms and a dorsally exophytic right brainstem and middle cerebellar peduncle hamartoma, following 2 prior subtotal resections. The authors recommended a third suboccipital craniotomy with intraoperative electrocorticography, which revealed interictal spiking from an intralesional depth electrode. Near-total resection led to durable seizure freedom.

LESSONS

Although posterior fossa lesions are rarely associated with epileptiform activity, this case demonstrates that pediatric patients with epileptic hemifacial spasms associated with a posterior fossa lesion may respond favorably to resection. Furthermore, this case demonstrates that intralesional electrocorticography can detect epileptic activity in posterior fossa lesions, which may predict postoperative seizure outcomes. https://thejns.org/doi/10.3171/CASE2452.

Implications of a De Novo Variant in the SOX12 Gene in a Patient with Generalized Epilepsy, Intellectual Disability, and Childhood Emotional Behavioral Disorders

SRY-box transcription factor (SOX) genes, a recently discovered gene family, play crucial roles in the regulation of neuronal stem cell proliferation and glial differentiation during nervous system development and neurogenesis. Whole exome sequencing (WES) in patients presenting with generalized epilepsy, intellectual disability, and childhood emotional behavioral disorder, uncovered a de novo variation within SOX12 gene. Notably, this gene has never been associated with neurodevelopmental disorders. No variants in known genes linked with the patient's symptoms have been detected by the WES Trio analysis. To date, any MIM phenotype number associated with intellectual developmental disorder has not been assigned for SOX12. In contrast, both SOX4 and SOX11 genes within the same C group (SoxC) of the Sox gene family have been associated with neurodevelopmental disorders. The variant identified in the patient here described was situated within the critical high-mobility group (HMG) functional site of the SOX12 protein. This domain, in the Sox protein family, is essential for DNA binding and bending, as well as being responsible for transcriptional activation or repression during the early stages of gene expression. Sequence alignment within SoxC (SOX12, SOX4 and SOX11) revealed a high conservation rate of the HMG region. The in silico predictive analysis described this novel variant as likely pathogenic. Furthermore, the mutated protein structure predictions unveiled notable changes with potential deleterious effects on the protein structure. The aim of this study is to establish a correlation between the SOX12 gene and the symptoms diagnosed in the patient.

Individual cerebellar metabolic connectome in patients with MTLE and NTLE associated with surgical prognosis

PURPOSE

This study aimed to comprehensively explore the different metabolic connectivity topological changes in MTLE and NTLE, as well as their association with surgical outcomes.

METHODS

This study enrolled a cohort of patients with intractable MTLE and NTLE. Each individual's metabolic connectome, as determined by Kullback-Leibler divergence similarity estimation for the [18F]FDG PET image, was employed to conduct a comprehensive analysis of the cerebral metabolic network. Alterations in network connectivity were assessed by extracting and evaluating the strength of edge and weighted connectivity. By utilizing these two connectivity strength metrics with the cerebellum, we explored the network properties of connectivity and its association with prognosis in surgical patients.

RESULTS

Both MTLE and NTLE patients exhibited substantial alterations in the connectivity of the metabolic network at the edge and nodal levels (p < 0.01, FDR corrected). The key disparity between MTLE and NTLE was observed in the cerebellum. In MTLE, there was a predominance of increased connectivity strength in the cerebellum. Whereas, a decrease in cerebellar connectivity was identified in NTLE. It was found that in MTLE, higher edge connectivity and weighted connectivity strength in the contralateral cerebellar hemisphere correlated with improved surgical outcomes. Conversely, in NTLE, a higher edge metabolic connectivity strength in the ipsilateral cerebellar hemisphere suggested a worse surgical prognosis.

CONCLUSION

The cerebellum exhibits distinct topological characteristics in the metabolic networks between MTLE and NTLE. The hyper- or hypo-metabolic connectivity in the cerebellum may be a prognostic biomarker of surgical prognosis, which might aid in therapeutic decision-making for TLE individuals.

Early and widespread engagement of the cerebellum during hippocampal epileptiform activity Format: Brief Communication

Despite research illustrating the cerebellum may be a critical circuit element in the epilepsies, remarkably little is known about cerebellar engagement during seizures. We therefore implemented a novel method for repeated imaging of the cerebellum in awake, chronically epileptic animals. We found widespread changes in cerebellar calcium signals during behavioral seizures and during hippocampal seizures that remained electrographic only, arguing against cerebellar modulation simply reflecting motor components. Moreover, even brief interictal spikes produced widespread alterations in cerebellar activity. Changes were noted in the anterior and posterior cerebellum, along the midline, and both ipsilaterally and contralaterally to the seizure focus. Remarkably, changes in the cerebellum also occurred prior to any noticeable change in the hippocampal electrographic recordings, suggesting a special relationship between the cerebellum and hippocampal epileptiform activity. Together these results underscore the importance of the cerebellum in epilepsy, warranting a more consistent consideration of the cerebellum when evaluating epilepsy patients.

The cerebellum and its connections to other brain structures involved in motor and non-motor functions: A comprehensive review

The cerebellum has a large network of neurons that communicate with several brain structures and participate in different functions. Recent studies have demonstrated that the cerebellum is not only associated with motor functions but also participates in several non-motor functions. It is suggested that the cerebellum can modulate behavior through many connections with different nervous system structures in motor, sensory, cognitive, autonomic, and emotional processes. Recently, a growing number of clinical and experimental studies support this theory and provide further evidence. In light of recent findings, a comprehensive review is needed to summarize the knowledge on the influence of the cerebellum on the processing of different functions. Therefore, the aim of this review was to describe the neuroanatomical aspects of the activation of the cerebellum and its connections with other structures of the central nervous system in different behaviors.

Optimized microburst VNS elicits fMRI responses beyond thalamic-specific response from standard VNS

OBJECTIVE

In parallel to standard vagus nerve stimulation (VNS), microburst stimulation delivery has been developed. We evaluated the fMRI-related signal changes associated with standard and optimized microburst stimulation in a proof-of-concept study (NCT03446664).

METHODS

Twenty-nine drug-resistant epilepsy patients were prospectively implanted with VNS. Three 3T fMRI scans were collected 2 weeks postimplantation. The maximum tolerated VNS intensity was determined prior to each scan starting at 0.125 mA with 0.125 mA increments. FMRI scans were block-design with alternating 30 sec stimulation [ON] and 30 sec no stimulation [OFF]: Scan 1 utilized standard VNS and Scan 3 optimized microburst parameters to determine target settings. Semi-automated on-site fMRI data processing utilized ON-OFF block modeling to determine VNS-related fMRI activation per stimulation setting. Anatomical thalamic mask was used to derive highest mean thalamic t-value for determination of microburst stimulation parameters. Paired t-tests corrected at P < 0.05 examined differences in fMRI responses to each stimulation type.

RESULTS

Standard and microburst stimulation intensities at Scans 1 and 3 were similar (P = 0.16). Thalamic fMRI responses were obtained in 28 participants (19 with focal; 9 with generalized seizures). Group activation maps showed standard VNS elicited thalamic activation while optimized microburst VNS showed widespread activation patterns including thalamus. Comparison of stimulation types revealed significantly greater cerebellar, midbrain, and parietal fMRI signal changes in microburst compared to standard VNS. These differences were not associated with seizure responses.

INTERPRETATION

While standard and optimized microburst VNS elicited thalamic activation, microburst also engaged other brain regions. Relationship between these fMRI activation patterns and clinical response warrants further investigation.

CLINICAL TRIAL REGISTRATION

The study was registered with clinicaltrials.gov (NCT03446664).

Optogenetics in taste research: A decade of enlightenment

The electrophysiological function of the tongue involves complicated activities in taste sense, producing the perceptions of salty, sweet, bitter, and sour. However, therapies and prevention of taste loss arising from dysfunction in electrophysiological activity require further fundamental research. Optogenetics has revolutionized neuroscience and brought the study of sensory system to a higher level in taste. The year 2022 marks a decade of developments of optogenetics in taste since this technology was adopted from neuroscience and applied to the taste research. This review summarizes a decade of advances that define near-term translation with optogenetic tools, and newly-discovered mechanisms with the applications of these tools. The main limitations and opportunities for optogenetics in taste research are also discussed.

Brain activation and connection across resting and motor-task states in patients with generalized tonic-clonic seizures

AIMS

Motor abnormalities have been identified as one common symptom in patients with generalized tonic-clonic seizures (GTCS) inspiring us to explore the disease in a motor execution condition, which might provide novel insight into the pathomechanism.

METHODS

Resting-state and motor-task fMRI data were collected from 50 patients with GTCS, including 18 patients newly diagnosed without antiepileptic drugs (ND_GTCS) and 32 patients receiving antiepileptic drugs (AEDs_GTCS). Motor activation and its association with head motion and cerebral gradients were assessed. Whole-brain network connectivity across resting and motor states was further calculated and compared between groups.

RESULTS

All patients showed over-activation in the postcentral gyrus and the ND_GTCS showed decreased activation in putamen. Specifically, activation maps of ND_GTCS showed an abnormal correlation with head motion and cerebral gradient. Moreover, we detected altered functional network connectivity in patients within states and across resting and motor states by using repeated-measures analysis of variance. Patients did not show abnormal connectivity in the resting state, while distributed abnormal connectivity in the motor-task state. Decreased across-state network connectivity was also found in all patients.

CONCLUSION

Convergent findings suggested the over-response of activation and connection of the brain to motor execution in GTCS, providing new clues to uncover motor susceptibility underlying the disease.

Delving into the significance of the His289Tyr single-nucleotide polymorphism in the glutamate ionotropic receptor kainate-1 (Grik1) gene of a genetically audiogenic seizure model

Genetic abnormalities affecting glutamate receptors are central to excitatory overload-driven neuronal mechanisms that culminate in seizures, making them pivotal targets in epilepsy research. Increasingly used to advance this field, the genetically audiogenic seizure hamster from Salamanca (GASH/Sal) exhibits generalized seizures triggered by high-intensity acoustic stimulation and harbors significant genetic variants recently identified through whole-exome sequencing. Here, we addressed the influence of the missense single-nucleotide polymorphism (C9586732T, p.His289Tyr) in the glutamate receptor ionotropic kainate-1 (Grik1) gene and its implications for the GASH/Sal seizure susceptibility. Using a protein 3D structure prediction, we showed a potential effect of this sequence variation, located in the amino-terminal domain, on the stability and/or conformation of the kainate receptor subunit-1 protein (GluK1). We further employed a multi-technique approach, encompassing gene expression analysis (RT-qPCR), Western blotting, and immunohistochemistry in bright-field and confocal fluorescence microscopy, to investigate critical seizure-associated brain regions in GASH/Sal animals under seizure-free conditions compared to matched wild-type controls. We detected disruptions in the transcriptional profile of the Grik1 gene within the audiogenic seizure-associated neuronal network. Alterations in GluK1 protein levels were also observed in various brain structures, accompanied by an unexpected lower molecular weight band in the inferior and superior colliculi. This correlated with substantial disparities in GluK1-immunolabeling distribution across multiple brain regions, including the cerebellum, hippocampus, subdivisions of the inferior and superior colliculi, and the prefrontal cortex. Notably, the diffuse immunolabeling accumulated within perikarya, axonal fibers and terminals, exhibiting a prominent concentration in proximity to the cell nucleus. This suggests potential disturbances in the GluK1-trafficking mechanism, which could subsequently affect glutamate synaptic transmission. Overall, our study sheds light on the genetic underpinnings of seizures and underscores the importance of investigating the molecular mechanisms behind synaptic dysfunction in epileptic neural networks, laying a crucial foundation for future research and therapeutic strategies targeting GluK1-containing kainate receptors.

Speech and Language Delays Associated With New-Onset Seizures Revealing Dandy-Walker Variant

Dandy-Walker malformation or syndrome is a rare congenital deformity in which the cerebellar vermis is hypoplastic and upwardly rotated, the fourth ventricle enlarged, and the posterior fossa cystically dilated. It represents the most common type of posterior fossa malformations that are usually diagnosed before the age of one year old. We present a seven-year-old boy with a history of neonatal hypotonia and delayed walking, who presented with speech and language difficulties. His physical examination and cognitive tests were unremarkable. The patient's brain magnetic resonance imaging showed a partial defect of the inferior part of the cerebellar vermis and communication between a normal-sized cisterna magna and the fourth ventricle. There were no other coexisting central nervous system or systemic anomalies. This isolated inferior vermian hypoplasia was compatible with an uncommon variant of the Dandy-Walker syndrome. The aim of this report is to provide insight into the importance of implementing a pediatrician-psychiatrist collaboration in the clinical decision-making process of such developmental delay cases. What makes the present case further interesting are the new-onset unprovoked seizures that developed and recurred in the setting of such isolated and less severe posterior fossa anomaly, raising both diagnostic and therapeutic challenges.

The bidirectional relationship between the cerebellum and seizure networks: a double-edged sword

Epilepsy is highly prevalent and notoriously pharmacoresistant. New therapeutic interventions are urgently needed, both for preventing the seizures themselves as well as negative outcomes and comorbidities associated with chronic epilepsy. While the cerebellum is not traditionally associated with epilepsy or seizures, research over the past decade has outlined the cerebellum as a brain region that is uniquely suited for both therapeutic needs. This review discusses our current understanding of the cerebellum as a key node within seizure networks, capable of both attenuating seizures in several animal models, and conversely, prone to altered structure and function in chronic epilepsy. Critical next steps are to advance therapeutic modulation of the cerebellum more towards translation, and to provide a more comprehensive characterization of how the cerebellum is impacted by chronic epilepsy, in order to subvert negative outcomes.

Neocortical and cerebellar malformations affect flurothyl-induced seizures in female C57BL/6J mice

Brain malformations cause cognitive disability and seizures in both human and animal models. Highly laminated structures such as the neocortex and cerebellum are vulnerable to malformation, affecting lamination and neuronal connectivity as well as causing heterotopia. The objective of the present study was to determine if sporadic neocortical and/or cerebellar malformations in C57BL/6J mice are correlated with reduced seizure threshold. The inhaled chemi-convulsant flurothyl was used to induce generalized, tonic-clonic seizures in male and female C57BL/6J mice, and the time to seizure onset was recorded as a functional correlate of brain excitability changes. Following seizures, mice were euthanized, and brains were extracted for histology. Cryosections of the neocortex and cerebellar vermis were stained and examined for the presence of molecular layer heterotopia as previously described in C57BL/6J mice. Over 60% of mice had neocortical and/or cerebellar heterotopia. No sex differences were observed in the prevalence of malformations. Significantly reduced seizure onset time was observed dependent on sex and the type of malformation present. These results raise important questions regarding the presence of malformations in C57BL/6J mice used in the study of brain development, epilepsy, and many other diseases of the nervous system.

Microstructural evaluation of the brain with advanced magnetic resonance imaging techniques in cases of electrical status epilepticus during sleep (ESES)

Background/aim

The cause and treatment of electrical status epilepticus during sleep (ESES), one of the epileptic encephalopathies of childhood, is unclear. The aim of this study was to evaluate possible microstructural abnormalities in the brain using advanced magnetic resonance imaging (MRI) techniques in ESES patients with and without genetic mutations.

Materials and methods

This research comprised 12 ESES patients without structural thalamic lesions (6 with genetic abnormalities and 6 without) and 12 healthy children. Whole-exome sequencing was used for the genetic mutation analysis. Brain MRI data were evaluated using tractus-based spatial statistics, voxel-based morphometry, a local gyrification index, subcortical shape analysis, FreeSurfer volume, and cortical thickness. The data of the groups were compared.

Results

The mean age in the control group was 9.05 ± 1.85 years, whereas that in the ESES group was 9.45 ± 2.72 years. Compared to the control group, the ESES patients showed higher mean thalamus diffusivity (p < 0.05). ESES patients with genetic mutations had lower axial diffusivity in the superior longitudinal fasciculus and gray matter volume in the entorhinal region, accumbens area, caudate, putamen, cerebral white matter, and outer cerebellar areas. The superior and middle temporal cortical thickness increased in the ESES patients.

Conclusion

This study is important in terms of presenting the microstructural evaluation of the brain in ESES patients with advanced MRI analysis methods as well as comparing patients with and without genetic mutations. These findings may be associated with corticostriatal transmission, ictogenesis, epileptogenesis, neuropsychiatric symptoms, cognitive impairment, and cerebellar involvement in ESES. Expanded case-group studies may help to understand the physiology of the corticothalamic circuitry in its etiopathogenesis and develop secondary therapeutic targets for ESES.

Structural connections of the centromedian nucleus of thalamus and their relevance for neuromodulation in generalized drug-resistant epilepsy: insight from a tractography study

Background

Epilepsy is a widespread neurologic disorder and almost one-third of patients suffer from drug-resistant epilepsy (DRE). Neuromodulation targeting the centromediannucleus of the thalamus (CM) has been showing promising results for patients with generalized DRE who are not surgical candidates. Recently, the effect of CM- deep brain stimulation (DBS) in DRE patients was investigated in the Electrical Stimulation of Thalamus for Epilepsy of Lennox-Gastaut phenotype (ESTEL) trial, a monocentric randomized-controlled study. The same authors described a 'cold-spot' and a 'sweet-spot', which are defined as the volume of stimulation in the thalamus yielding the least and the best clinical response, respectively. However, it remains unclear which structural connections may contribute to the anti-seizure effect of the stimulation.

Objective

We investigated the differences in structural connectivity among CM, the sweet-spot and the cold-spot. Furthermore, we tried to validate our results in a cohort of DRE patients who underwent CM-DBS or CM-RNS (responsive neurostimulation). We hypothesized that the sweet-spot would share similar structural connectivity with responder patients.

Methods

By using the software FMRIB Software Library (FSL), probabilistic tractography was performed on 100 subjects from the Human Connectome Project to calculate the probability of connectivity of the whole CM, the sweet-spot and the cold-spot to 45 cortical and subcortical areas. Results among the three seeds were compared with multivariate analysis of variance (MANOVA). Similarly, the structural connectivity of volumes of tissue activated (VTAs) from eight DRE patients was investigated. Patients were divided into responders and non-responders based on the degree of reduction in seizure frequency, and the mean probabilities of connectivity were similarly compared between the two groups.

Results

The sweet-spot demonstrated a significantly higher probability of connectivity (p < 0.001) with the precentral gyrus, superior frontal gyrus, and the cerebellum than the whole CM and the cold-spot. Responder patients displayed a higher probability of connectivity with both ipsilateral (p = 0.011) and contralateral cerebellum (p = 0.04) than the non-responders.

Conclusion

Cerebellar connections seem to contribute to the beneficial effects of CM-neuromodulation in patients with drug-resistant generalized epilepsy.

The little brain and the seahorse: Cerebellar-hippocampal interactions

There is a growing appreciation for the cerebellum beyond its role in motor function and accumulating evidence that the cerebellum and hippocampus interact across a range of brain states and behaviors. Acute and chronic manipulations, simultaneous recordings, and imaging studies together indicate coordinated coactivation and a bidirectional functional connectivity relevant for various physiological functions, including spatiotemporal processing. This bidirectional functional connectivity is likely supported by multiple circuit paths. It is also important in temporal lobe epilepsy: the cerebellum is impacted by seizures and epilepsy, and modulation of cerebellar circuitry can be an effective strategy to inhibit hippocampal seizures. This review highlights some of the recent key hippobellum literature.

Dandy Walker-like malformation in an adult cat with seizures: clinical description and MRI characteristics

Case summary

A 2-year-old male neutered domestic shorthair cat was referred for investigation of a 10-month history of self-limiting, generalised tonic-clonic seizures. The cat was reported to be normal interictally but had always had a static abnormal gait. General physical examination was unremarkable. Neuroanatomical localisation was compatible with a diffuse cerebellar and diffuse forebrain lesion. Complete blood count, biochemistry, bile acid stimulation test, urinalysis, cisternal cerebrospinal fluid (CSF) analysis, Toxoplasma gondii serology and T gondii polymerase chain reaction in CSF were all unremarkable. MRI revealed an abnormal caudal fossa, absent cerebellar vermis and small cerebellar hemisphere with distension of the fourth ventricle. There were no forebrain abnormalities identified in the MRI or CSF changes that could justify the seizures. Considering the clinical presentation, the cat's neurological examination and MRI features, a presumptive diagnosis of Dandy Walker-like malformation (DWLM) and epilepsy of unknown aetiology was made.

Relevance and novel information

This is the first case report of an adult cat diagnosed with cerebellar malformation resembling DWLM and concomitant seizures, its MRI characteristics and long-term follow-up. The 3-year follow-up consultation revealed static neurological status with 2-4 seizures per year. The cat's quality of life remained good at the time of writing.

Altered Cerebro-Cerebellar Effective Connectivity in New-Onset Juvenile Myoclonic Epilepsy

(1) Objective: Resting-state fMRI studies have indicated that juvenile myoclonic epilepsy (JME) could cause widespread functional connectivity disruptions between the cerebrum and cerebellum. However, the directed influences or effective connectivities (ECs) between these brain regions are poorly understood. In the current study, we aimed to evaluate the ECs between the cerebrum and cerebellum in patients with new-onset JME. (2) Methods: Thirty-four new-onset JME patients and thirty-four age-, sex-, and education-matched healthy controls (HCs) were included in this study. We compared the degree centrality (DC) between the two groups to identify intergroup differences in whole-brain functional connectivity. Then, we used a Granger causality analysis (GCA) to explore JME-caused changes in EC between cerebrum regions and cerebellum regions. Furthermore, we applied a correlation analysis to identify associations between aberrant EC and disease severity in patients with JME. (3) Results: Compared to HCs, patients with JME showed significantly increased DC in the left cerebellum posterior lobe (CePL.L), the right inferior temporal gyrus (ITG.R) and the right superior frontal gyrus (SFG.R), and decreased DC in the left inferior frontal gyrus (IFG.L) and the left superior temporal gyrus (STG.L). The patients also showed unidirectionally increased ECs from cerebellum regions to the cerebrum regions, including from the CePL.L to the right precuneus (PreCU.R), from the left cerebellum anterior lobe (CeAL.L) to the ITG.R, from the right cerebellum posterior lobe (CePL.R) to the IFG.L, and from the left inferior semi-lunar lobule of the cerebellum (CeISL.L) to the SFG.R. Additionally, the EC from the CeISL.L to the SFG.R was negatively correlated with the disease severity. (4) Conclusions: JME patients showed unidirectional EC disruptions from the cerebellum to the cerebrum, and the negative correlation between EC and disease severity provides a new perspective for understanding the cerebro-cerebellar neural circuit mechanisms in JME.

Refractory psychiatric symptoms and seizure associated with Dandy-Walker syndrome: A case report and literature review

BACKGROUNDS

Dandy-Walker syndrome (DWS) is a group of brain malformations which occasionally accompanied by psychotic symptoms. The co-occurrence of DWS and epilepsy in children is quite rare.

CASE DESCRIPTION

We reported a 14-year-old male who presented with a 8-month history of inconsistent upper limb tremor and accidental seizure. The MRI showed the typical alterations of DWS: cystic dilatation of the fourth ventricle, vermian hypoplasia, enlarged posterior fossa. He received the ventriculoperitoneal shunting (VPS) placement for hydrocephalus and had a symptom-free period for 8 days. Then he experienced a recurrence of involuntary upper limb tremor and behavior disturbance after decreasing the pressure of cerebrospinal fluid (CSF) from 150 to 130 mm Hg. After being treated with Olanzapine 10 mg/d, Clonazepam 3 mg/qn and Valproate acid (VPA) 500 mg/bid for nearly a month, his mental status and psychotic symptoms fluctuated. A search of Pub Med showed little report of hydrocephalus and DWS comorbidity with seizure and psychosis. Here we presented the whole process of a rare disease from the very beginning with all his symptoms, examinations and treatments.

CONCLUSION

VPS placement surgery at an earlier stage may be an effective way to avoid inevitable brain damage so as to improve the clinical outcomes for patients with DWS. Continued treatment with regard to DWS condition may include shunt placement, but it mainly focus on developmental concerns, with occupational and physical therapy along with ongoing supportive psychotherapy to improve the coping skills and quality of life.

Abnormalities of hemispheric specialization in drug-naïve and drug-receiving self-limited epilepsy with centrotemporal spikes

PURPOSE

Self-limited epilepsy with centrotemporal spikes (SLECTS) is a pediatric benign epilepsy but often accompanied by subsequent (in adulthood) functional changes such as language, which are thought to have distinct areas of hemispheric lateralization and functional differentiation. This study aimed to explore hemispheric specialization measured by resting-state functional magnetic resonance imaging (rs-fMRI) functional connectivity in drug-naïve and drug-receiving SLECTS.

METHODS

Hemispheric specialization was quantified in three groups of children, including 21 drug-naïve patients (DNP) with SLECTS, 34 drug-receiving patients (DRP) with SLECTS and 36 demographically matched typical development (TD).

RESULTS

Compared with the TD group, both the DNP and DRP groups exhibited significantly higher specialization in the left superior temporal gyrus, right parahippocampus, left putamen, and right caudate. The DNP group exhibited significantly higher hemispheric specialization in the right precentral gyrus and right inferior temporal gyrus, while the DRP group demonstrated significantly higher hemispheric specialization in the left postcentral gyrus and right hippocampus than the TD group. Furthermore, bilateral cerebellum_6 showed opposing hemispheric specialization trends in the two patient groups. Further meta-analytical mapping demonstrated that hemispheric specialization-related differential brain regions are primarily involved in language processing.

CONCLUSION

Our findings showed that children with SLECTS had altered hemispheric specialization, mainly in language processing regions, suggesting both abnormal intrahemispheric segregation and interhemispheric integration in these children.

Amplitude synchronization of spontaneous activity of medial and lateral temporal gyri reveals altered thalamic connectivity in patients with temporal lobe epilepsy

In this study, we examined whether amplitude synchronization of medial (MTL) and lateral (LTL) temporal lobes can detect unique alterations in patients with MTL epilepsy (mTLE) with mesial temporal sclerosis (MTS). This was a retrospective study of preoperative resting-state fMRI (rsfMRI) data from 31 patients with mTLE with MTS (age 23-69) and 16 controls (age 21-35). fMRI data were preprocessed based on a multistep preprocessing pipeline and registered to a standard space. Using each subject's T1-weighted scan, the MTL and LTL were automatically segmented, manually revised and then fit to a standard space using a symmetric normalization registration algorithm. Dual regression analysis was applied on preprocessed rsfMRI data to detect amplitude synchronization of medial and lateral temporal segments with the rest of the brain. We calculated the overlapped volume ratio of synchronized voxels within specific target regions including the thalamus (total and bilateral). A general linear model was used with Bonferroni correction for covariates of epilepsy duration and age of patient at scan to statistically compare synchronization in patients with mTLE with MTS and controls, as well as with respect to whether patients remained seizure-free (SF) or not (NSF) after receiving epilepsy surgery. We found increased ipsilateral positive connectivity between the LTLs and the thalamus and contralateral negative connectivity between the MTLs and the thalamus in patients with mTLE with MTS compared to controls. We also found increased asymmetry of functional connectivity between temporal lobe subregions and the thalamus in patients with mTLE with MTS, with increased positive connectivity between the LTL and the lesional-side thalamus as well as increased negative connectivity between the MTL and the nonlesional-side thalamus. This asymmetry was also seen in NSF patients but was not seen in SF patients and controls. Amplitude synchronization was an effective method to detect functional connectivity alterations in patients with mTLE with MTS. Patients with mTLE with MTS overall showed increased temporal-thalamic connectivity. There was increased functional involvement of the thalamus in MTS, underscoring its role in seizure spread. Increased functional thalamic asymmetry patterns in NSF patients may have a potential role in prognosticating patient response to surgery. Elucidating regions with altered functional connectivity to temporal regions can improve understanding of the involvement of different regions in the disease to potentially target for intervention or use for prognosis for surgery. Future studies are needed to examine the effectiveness of using patient-specific abnormalities in patterns to predict surgical outcome.

The Adhesion GPCR VLGR1/ADGRV1 Regulates the Ca2+ Homeostasis at Mitochondria-Associated ER Membranes

The very large G protein-coupled receptor (VLGR1, ADGRV1) is the largest member of the adhesion GPCR family. Mutations in VLGR1 have been associated with the human Usher syndrome (USH), the most common form of inherited deaf-blindness as well as childhood absence epilepsy. VLGR1 was previously found as membrane–membrane adhesion complexes and focal adhesions. Affinity proteomics revealed that in the interactome of VLGR1, molecules are enriched that are associated with both the ER and mitochondria, as well as mitochondria-associated ER membranes (MAMs), a compartment at the contact sites of both organelles. We confirmed the interaction of VLGR1 with key proteins of MAMs by pull-down assays in vitro complemented by in situ proximity ligation assays in cells. Immunocytochemistry by light and electron microscopy demonstrated the localization of VLGR1 in MAMs. The absence of VLGR1 in tissues and cells derived from VLGR1-deficient mouse models resulted in alterations in the MAM architecture and in the dysregulation of the Ca²⁺ transient from ER to mitochondria. Our data demonstrate the molecular and functional interaction of VLGR1 with components in MAMs and point to an essential role of VLGR1 in the regulation of Ca²⁺ homeostasis, one of the key functions of MAMs.

Not All Paths are Equal: Stimulating Specific Cerebellar Outputs Inhibits Hippocampal Seizures

Distinct Fastigial Output Channels and Their Impact on Temporal Lobe Seizures

Streng ML, Tetzlaff MR, Krook-Magnuson E. 2021. J. Neurosci. 41(49):10091-10107. doi:10.1523/JNEUROSCI.0683-21.2021.

Despite being canonically considered a motor control structure, the cerebellum is increasingly recognized for important roles in processes beyond this traditional framework, including seizure suppression. Excitatory fastigial neurons project to a large number of downstream targets, and it is unclear whether this broad targeting underlies seizure suppression, or whether a specific output may be sufficient. To address this question, we used the intrahippocampal kainic acid mouse model of temporal lobe epilepsy, male and female animals, and a dual-virus approach to selectively label and manipulate fastigial outputs. We examined fastigial neurons projecting to the superior colliculus, medullary reticular formation, and central lateral nucleus of the thalamus, and found that these comprise largely nonoverlapping populations of neurons that send collaterals to unique sets of additional, somewhat overlapping, thalamic and brainstem regions. We found that neither optogenetic stimulation of superior colliculus nor reticular formation output channels attenuated hippocampal seizures. In contrast, on-demand stimulation of fastigial neurons targeting the central lateral nucleus robustly inhibited seizures. Our results indicate that fastigial control of hippocampal seizures does not require simultaneous modulation of many fastigial output channels. Rather, selective modulation of the fastigial output channel to the central lateral thalamus, specifically, is sufficient for seizure control. More broadly, our data highlight the concept of specific cerebellar output channels, whereby discrete cerebellar nucleus neurons project to specific aggregates of downstream targets, with important consequences for therapeutic interventions.

Disruption of Cerebellar–Cerebral Functional Connectivity in Temporal Lobe Epilepsy and the Connection to Language and Cognitive Functions

Objective

To investigate the changes in the cerebellar-cerebral language network in temporal lobe epilepsy (TLE) patients from the cerebellar perspective, the research analyzes the changes of language and cognitive network in terms of functional connectivity (FC), as well as their efficiency of the reorganization were evaluated basing on relationship between the network metrics and neuropsychological scale scores.

Methods

30 TLE patients and 30 healthy controls were recruited. Brain activity was evaluated by voxel-mirrored homotopic connectivity analysis (VMHC). Two groups were analyzed and compared in terms of language FC using the following methods: Seed-to-Voxel analysis, pairwise correlations [region of interest(ROI)-to-ROI] and graph theory. Correlation analysis was performed between network properties and neuropsychological score.

Results

Compared with healthy participants, VMHC values in the Cerebellum Anterior Lobe, Frontal Lobe, Frontal_Sup_R/L, Cingulum_Ant_R/L, and Cingulum_Mid_R/L were decreased in TLE patients. Decreased FC was observed from the Cerebelum_10_R to the left inferior frontal gyrus, from the Cerebelum_6_R to the left Lingual Gyrus, from the Cerebelum_4_5_R to left Lingual Gyrus, left Cuneal Cortex and Precuneous Cortex, from the Cerebelum_3_R to Brain-Stem, and from the Cerebelum_Crus1_L to Cerebelum_6_R in TLE patients. The FC was enhanced between bilateral Cingulum_Mid and angular gyrus and frontoparietal insular cranium, between Frontal_Sup_Med L and left/right superior temporal gyrus (pSTG l/r), while it was decreased between left middle temporal gyrus and pSTG l/r. Compared with controls, the Betweenness Centrality (BC) of the right superior marginal gyrus (SMG), Temporal_Pole_Mid_R and Temporal_Mid_L as well as the Degree Centrality (DC) and Nodal Efficiency (NE) of the right SMG were lower in TLE patients. Further analysis showed that decreased VMHC in bilateral Cerebellum Anterior Lobe was positively correlated with the Boston Naming Test score in TLE patients, but it was negatively correlated with the Verbal Fluency Test score. The NE and DC of SMG_R were both negatively correlated with visual perception score in Montreal Cognitive Assessment.

Conclusion

Our results suggest that presence of abnormalities in the static functional connectivity and the language and cognitive network of TLE patients. Cerebellum potentially represents an intervention target for delaying or improving language and cognitive deficits in patients with TLE.

AntimiR targeting of microRNA-134 reduces seizures in a mouse model of Angelman syndrome

Angelman syndrome (AS) is a severe neurodevelopmental disorder featuring ataxia, cognitive impairment, and drug-resistant epilepsy. AS is caused by mutations or deletion of the maternal copy of the paternally imprinted UBE3A gene, with current precision therapy approaches focusing on re-expression of UBE3A. Certain phenotypes, however, are difficult to rescue beyond early development. Notably, a cluster of microRNA binding sites was reported in the untranslated Ube3a1 transcript, including for miR-134, suggesting that AS may be associated with microRNA dysregulation. Here, we report levels of miR-134 and key targets are normal in the hippocampus of mice carrying a maternal deletion of Ube3a (Ube3a ^m-/p+ ). Nevertheless, intracerebroventricular injection of an antimiR oligonucleotide inhibitor of miR-134 (Ant-134) reduced audiogenic seizure severity over multiple trials in 21- and 42-day-old AS mice. Interestingly, Ant-134 also improved distance traveled and center crossings of AS mice in the open-field test. Finally, we show that silencing miR-134 can upregulate targets of miR-134 in neurons differentiated from Angelman patient-derived induced pluripotent stem cells. These findings indicate that silencing miR-134 and possibly other microRNAs could be useful to treat clinically relevant phenotypes with a later developmental window in AS.

Controlling absence seizures from the cerebellar nuclei via activation of the Gq signaling pathway

Absence seizures (ASs) are characterized by pathological electrographic oscillations in the cerebral cortex and thalamus, which are called spike-and-wave discharges (SWDs). Subcortical structures, such as the cerebellum, may well contribute to the emergence of ASs, but the cellular and molecular underpinnings remain poorly understood. Here we show that the genetic ablation of P/Q-type calcium channels in cerebellar granule cells (quirky) or Purkinje cells (purky) leads to recurrent SWDs with the purky model showing the more severe phenotype. The quirky mouse model showed irregular action potential firing of their cerebellar nuclei (CN) neurons as well as rhythmic firing during the wave of their SWDs. The purky model also showed irregular CN firing, in addition to a reduced firing rate and rhythmicity during the spike of the SWDs. In both models, the incidence of SWDs could be decreased by increasing CN activity via activation of the G_q-coupled designer receptor exclusively activated by designer drugs (DREADDs) or via that of the G_q-coupled metabotropic glutamate receptor 1. In contrast, the incidence of SWDs was increased by decreasing CN activity via activation of the inhibitory G_i/o-coupled DREADD. Finally, disrupting CN rhythmic firing with a closed-loop channelrhodopsin-2 stimulation protocol confirmed that ongoing SWDs can be ceased by activating CN neurons. Together, our data highlight that P/Q-type calcium channels in cerebellar granule cells and Purkinje cells can be relevant for epileptogenesis, that G_q-coupled activation of CN neurons can exert anti-epileptic effects and that precisely timed activation of the CN can be used to stop ongoing SWDs.

Altered Cerebral Blood Flow is Linked to Disease Duration in Patients with Generalized tonic‒clonic Seizures

PURPOSE

To investigate cerebral blood flow (CBF) characteristics in individuals with generalized tonic‒clonic seizures (GTCS) during the interictal phase using voxel-based analysis of 3D pseudocontinuous arterial spin labeling (PCASL).

PATIENTS AND METHODS

Patients with GTCS (GTCS group) (during the interictal period) and healthy volunteers (control group) underwent head MR imaging with a 3.0T MR scanner with a 3D PCASL sequence. CBF was compared between the two groups. Spearman correlations of CBF in regions of interest (ROIs) in GTCS patients with the duration of disease and age of onset were analyzed and corrected using the false discovery rate (FDR).

RESULTS

Twenty patients with GTCS (GTCS group) and twenty healthy volunteers (control group) were recruited for this study. On 3D PCASL, (1) GTCS patients had lower CBF in the brainstem, right cerebellum, right inferior temporal gyrus, parahippocampal gyrus, superior frontal gyrus, middle frontal gyrus, triangular part of inferior frontal gyrus, left temporal pole of superior temporal gyrus and thalamus and had higher CBF in the bilateral superior parietal gyri, precuneus, precentral gyri, postcentral gyri, and left dorsolateral superior frontal gyrus than controls. (2) The CBF of the right temporal pole of the middle temporal gyrus was negatively correlated with the duration of disease (P_FDRcorrected<0.05), with a correlation coefficient r of -0.7333 and a P_FDRcorrected value of 0.04.

CONCLUSION

Voxel-based analysis of 3D PCASL imaging can be used to sensitively detect brain perfusion differences in GTCS patients. The decrease in CBF in the right temporal pole of the middle temporal gyrus may be associated with disease onset. These findings may offer new perspectives on the pathogenesis of GTCS and the underlying pathophysiological changes associated with perfusion.

Distinct Fastigial Output Channels and Their Impact on Temporal Lobe Seizures

Despite being canonically considered a motor control structure, the cerebellum is increasingly recognized for important roles in processes beyond this traditional framework, including seizure suppression. Excitatory fastigial neurons project to a large number of downstream targets, and it is unclear whether this broad targeting underlies seizure suppression, or whether a specific output may be sufficient. To address this question, we used the intrahippocampal kainic acid mouse model of temporal lobe epilepsy, male and female animals, and a dual-virus approach to selectively label and manipulate fastigial outputs. We examined fastigial neurons projecting to the superior colliculus, medullary reticular formation, and central lateral nucleus of the thalamus, and found that these comprise largely nonoverlapping populations of neurons that send collaterals to unique sets of additional, somewhat overlapping, thalamic and brainstem regions. We found that neither optogenetic stimulation of superior colliculus nor reticular formation output channels attenuated hippocampal seizures. In contrast, on-demand stimulation of fastigial neurons targeting the central lateral nucleus robustly inhibited seizures. Our results indicate that fastigial control of hippocampal seizures does not require simultaneous modulation of many fastigial output channels. Rather, selective modulation of the fastigial output channel to the central lateral thalamus, specifically, is sufficient for seizure control. More broadly, our data highlight the concept of specific cerebellar output channels, whereby discrete cerebellar nucleus neurons project to specific aggregates of downstream targets, with important consequences for therapeutic interventions.SIGNIFICANCE STATEMENT The cerebellum has an emerging relationship with nonmotor systems and may represent a powerful target for therapeutic intervention in temporal lobe epilepsy. We find, as previously reported, that fastigial neurons project to numerous brain regions via largely segregated output channels, and that projection targets cannot be predicted simply by somatic locations within the nucleus. We further find that on-demand optogenetic excitation of fastigial neurons projecting to the central lateral nucleus of the thalamus-but not fastigial neurons projecting to the reticular formation, superior colliculus, or ventral lateral thalamus-is sufficient to attenuate hippocampal seizures.

Motor and higher-order functions topography of the human dentate nuclei identified with tractography and clustering methods

Deep gray matter nuclei are the synaptic relays, responsible to route signals between specific brain areas. Dentate nuclei (DNs) represent the main output channel of the cerebellum and yet are often unexplored especially in humans. We developed a multimodal MRI approach to identify DNs topography on the basis of their connectivity as well as their microstructural features. Based on results, we defined DN parcellations deputed to motor and to higher-order functions in humans in vivo. Whole-brain probabilistic tractography was performed on 25 healthy subjects from the Human Connectome Project to infer DN parcellations based on their connectivity with either the cerebral or the cerebellar cortex, in turn. A third DN atlas was created inputting microstructural diffusion-derived metrics in an unsupervised fuzzy c-means classification algorithm. All analyses were performed in native space, with probability atlas maps generated in standard space. Cerebellar lobule-specific connectivity identified one motor parcellation, accounting for about 30% of the DN volume, and two non-motor parcellations, one cognitive and one sensory, which occupied the remaining volume. The other two approaches provided overlapping results in terms of geometrical distribution with those identified with cerebellar lobule-specific connectivity, although with some differences in volumes. A gender effect was observed with respect to motor areas and higher-order function representations. This is the first study that indicates that more than half of the DN volumes is involved in non-motor functions and that connectivity-based and microstructure-based atlases provide complementary information. These results represent a step-ahead for the interpretation of pathological conditions involving cerebro-cerebellar circuits.

Neuroprotective Effect of Taurine against Cell Death, Glial Changes, and Neuronal Loss in the Cerebellum of Rats Exposed to Chronic-Recurrent Neuroinflammation Induced by LPS

The present study investigated the neuroprotective effect of taurine against the deleterious effects of chronic-recurrent neuroinflammation induced by LPS in the cerebellum of rats. Adult male Wistar rats were treated with taurine for 28 days. Taurine was administered at a dose of 30 or 100 mg/kg, by gavage. On days 7, 14, 21, and 28, the animals received LPS (250 μg/kg) intraperitoneally. The vehicle used was saline. The animals were divided into six groups: vehicle, taurine 30 mg/kg, taurine 100 mg/kg, LPS, LPS plus taurine 30 mg/kg, and LPS plus taurine 100 mg/kg. On day 29, the animals were euthanized, and the cerebellum was removed and prepared for immunofluorescence analysis using antibodies of GFAP, NeuN, CD11b, and cleaved caspase-3. LPS group showed a reduction in the immunoreactivity of GFAP in the arbor vitae and medullary center and of NeuN in the granular layer of the cerebellar cortex. LPS increased the immunoreactivity of CD11b in the arbor vitae and in the medullary center. Taurine protected against these effects induced by LPS in immunoreactivity of GFAP, NeuN, and CD11b, with the 100 mg/kg dose being the most effective. LPS induced an increase in the number of positive cleaved caspase-3 cells in the Purkinje cell layers, granular layer, arbor vitae, and medullary center. Taurine showed its antiapoptotic activity by reducing the cleaved caspase-3 cells in relation to the LPS group. Here, a potential neuroprotective role of taurine can be seen since this amino acid was effective in protecting the cerebellum of rats against cell death and changes in glial and neuronal cells in the face of chronic-recurrent neuroinflammation.

ATR regulates neuronal activity by modulating presynaptic firing

Ataxia Telangiectasia and Rad3-related (ATR) protein, as a key DNA damage response (DDR) regulator, plays an essential function in response to replication stress and controls cell viability. Hypomorphic mutations of ATR cause the human ATR-Seckel syndrome, characterized by microcephaly and intellectual disability, which however suggests a yet unknown role for ATR in non-dividing cells. Here we show that ATR deletion in postmitotic neurons does not compromise brain development and formation; rather it enhances intrinsic neuronal activity resulting in aberrant firing and an increased epileptiform activity, which increases the susceptibility of ataxia and epilepsy in mice. ATR deleted neurons exhibit hyper-excitability, associated with changes in action potential conformation and presynaptic vesicle accumulation, independent of DDR signaling. Mechanistically, ATR interacts with synaptotagmin 2 (SYT2) and, without ATR, SYT2 is highly upregulated and aberrantly translocated to excitatory neurons in the hippocampus, thereby conferring a hyper-excitability. This study identifies a physiological function of ATR, beyond its DDR role, in regulating neuronal activity.

Deep Cerebellar Nuclei Functional Connectivity with Cerebral Cortex in Temporal Lobe Epilepsy With and Without Focal to Bilateral Tonic-Clonic Seizures: a Resting-State fMRI Study

We aimed to explore the altered functional connectivity patterns within cerebello-cerebral circuits in temporal lobe epilepsy (TLE) patients with and without focal to bilateral tonic-clonic seizures (FBTCS). Forty-two patients with unilateral TLE (21 with and 21 without FBTCS) and 22 healthy controls were recruited. We chose deep cerebellar nuclei as seed regions, calculated static and dynamic functional connectivity (sFC and dFC) in the patients with and without FBTCS and healthy controls, and compared sFC and dFC among the three groups. Correlation analyses were used to assess relationships between the significantly altered imaging features and patient clinical parameters. Compared to the group without FBTCS, the FBTCS group showed decreased sFC between the right dentate nuclei and left hemisphere regions including the middle frontal gyrus, superior temporal gyrus, superior medial frontal gyrus and posterior cingulate gyrus, and significantly increased dFC between the right interposed nuclei and contralateral precuneus. Relative to HCs, the FBTCS group demonstrated prominently decreased sFC between the right dentate nuclei and left middle frontal gyrus. No significant correlations between the altered imaging features and patient clinical parameters were observed. Our results suggest that the disrupted cerebello-cerebral FC might be related to cognitive impairment, epileptogenesis, and propagation of epileptic activities in patients with FBTCS.

Altered Protein Profiles During Epileptogenesis in the Pilocarpine Mouse Model of Temporal Lobe Epilepsy

Epilepsy is characterized by recurrent, spontaneous seizures and is a major contributor to the global burden of neurological disease. Although epilepsy can result from a variety of brain insults, in many cases the cause is unknown and, in a significant proportion of cases, seizures cannot be controlled by available treatments. Understanding the molecular alterations that underlie or are triggered by epileptogenesis would help to identify therapeutics to prevent or control progression to epilepsy. To this end, the moderate throughput technique of Reverse Phase Protein Arrays (RPPA) was used to profile changes in protein expression in a pilocarpine mouse model of acquired epilepsy. Levels of 54 proteins, comprising phosphorylation-dependent and phosphorylation-independent components of major signaling pathways and cellular complexes, were measured in hippocampus, cortex and cerebellum of mice at six time points, spanning 15 min to 2 weeks after induction of status epilepticus. Results illustrate the time dependence of levels of the commonly studied MTOR pathway component, pS6, and show, for the first time, detailed responses during epileptogenesis of multiple components of the MTOR, MAPK, JAK/STAT and apoptosis pathways, NMDA receptors, and additional cellular complexes. Also noted are time- and brain region- specific changes in correlations among levels of functionally related proteins affecting both neurons and glia. While hippocampus and cortex are primary areas studied in pilocarpine-induced epilepsy, cerebellum also shows significant time-dependent molecular responses.

Stimulating Solutions for Intractable Epilepsy

Implantable devices for controlling medically intractable seizures nondestructively are rapidly advancing. These offer reversible, potentially, restorative options beyond traditional, surgical procedures, which rely, largely on resection or ablation of selected brain sites. Several lines of, investigation aimed at improving efficacy of these devices are discussed, ranging from identifying novel subcortical, white matter, or cell-type specific targets to engineering advances for adaptive techniques based- on continuous, dynamic system analysis.

Deep Relational Reasoning for the Prediction of Language Impairment and Postoperative Seizure Outcome Using Preoperative DWI Connectome Data of Children With Focal Epilepsy

Prolonged seizures in children with focal epilepsy (FE) may impair language functions and often reoccur after surgical intervention. This study is aimed at developing a novel deep relational reasoning network to investigate whether conventional diffusion-weighted imaging connectome analysis can be improved when predicting expressive and receptive scores of preoperative language impairments and classifying postoperative seizure outcomes (seizure freedom or recurrence) in individual FE children. To deeply reason the dependencies of axonal connections that are sparsely distributed in the whole brain, this study proposes the "dilated CNN + RN", a dilated convolutional neural network (CNN) combined with a relation network (RN). The performance of the dilated CNN + RN was evaluated using whole brain connectome data from 51 FE children. It was found that when compared with other state-of-the-art algorithms, the dilated CNN + RN led to an average improvement of 90.2% and 97.3% in predicting expressive and receptive language scores, and 2.2% and 4% improvement in classifying seizure freedom and seizure recurrence, respectively. These improvements were independent of the prefixed connectome densities. Also, the dilated CNN + RN could provide an explainable artificial intelligence (AI) model by computing gradient-based regression/classification activation maps. This mapping analysis revealed left superior-medial frontal cortex, bilateral hippocampi, and cerebellum as crucial hubs, facilitating important connections that were most predictive of language function and seizure refractoriness after surgery.

Selective loss of the GABAAα1 subunit from Purkinje cells is sufficient to induce a tremor phenotype

Previously, an essential tremor-like phenotype has been noted in animals with a global knockout of the GABA_Aα1 subunit. Given the hypothesized role of the cerebellum in tremor, including essential tremor, we used transgenic mice to selectively knock out the GABA_Aα1 subunit from cerebellar Purkinje cells. We examined the resulting phenotype regarding impacts on inhibitory postsynaptic currents, survival rates, gross motor abilities, and expression of tremor. Purkinje cell specific knockout of the GABA_Aα1 subunit abolished all GABA_A-mediated inhibition in Purkinje cells, while leaving GABA_A-mediated inhibition to cerebellar molecular layer interneurons intact. Selective loss of GABA_Aα1 from Purkinje cells did not produce deficits on the accelerating rotarod, nor did it result in decreased survival rates. However, a tremor phenotype was apparent, regardless of sex or background strain. This tremor mimicked the tremor seen in animals with a global knockout of the GABA_Aα1 subunit, and, like essential tremor in patients, was responsive to ethanol. These findings indicate that reduced inhibition to Purkinje cells is sufficient to induce a tremor phenotype, highlighting the importance of the cerebellum, inhibition, and Purkinje cells in tremor.NEW & NOTEWORTHY Animals with a global knockout of the GABA_Aα1 subunit show a tremor phenotype reminiscent of essential tremor. Here we show that selective knockout of GABA_Aα1 from Purkinje cells is sufficient to produce a tremor phenotype, although this tremor is less severe than seen in animals with a global knockout. These findings illustrate that the cerebellum can play a key role in the genesis of the observed tremor phenotype.

Characterization of the Expression of the ATP-Gated P2X7 Receptor Following Status Epilepticus and during Epilepsy Using a P2X7-EGFP Reporter Mouse

Mounting evidence suggests that the ATP-gated P2X7 receptor contributes to increased hyperexcitability in the brain. While increased expression of P2X7 in the hippocampus and cortex following status epilepticus and during epilepsy has been repeatedly demonstrated, the cell type-specific expression of P2X7 and its expression in extra-hippocampal brain structures remains incompletely explored. In this study, P2X7 expression was visualized by using a transgenic mouse model overexpressing P2X7 fused to the fluorescent protein EGFP. The results showed increased P2X7-EGFP expression after status epilepticus induced by intra-amygdala kainic acid and during epilepsy in different brain regions including the hippocampus, cortex, striatum, thalamus and cerebellum, and this was most evident in microglia and oligodendrocytes. Co-localization of P2X7-EGFP with cell type-specific markers was not detected in neurons or astrocytes. These data suggest that P2X7 activation is a common pathological hallmark across different brain structures, possibly contributing to brain inflammation and neurodegeneration following acute seizures and during epilepsy.

When Drugs Do Not Work: Alternatives to Antiseizure Medications

PURPOSE OF REVIEW

Despite the increase in the number of novel antiseizure medications over the past 20 years, approximately one-third of patients will not have adequate seizure control on medications. For these patients, additional options need to be considered, including dietary, device, and surgical treatments. In addition, many complementary therapies can be considered as adjunctive treatment, with the intent of improving quality of life for persons with epilepsy and potentially allowing for improvement in seizure control.

RECENT FINDINGS

This review outlines established and developing treatments for drug-resistant epilepsy. Surgical treatments, including resective surgery and vagus nerve stimulation, have been routine care for several decades. In the last several years, new neurostimulation options have been approved (responsive neurostimulation and deep brain stimulation) or are under development (continuous subthreshold cortical stimulation). For patients with lesion or well-defined seizure-onset zones, less invasive options including laser ablation and ultrasound therapy provide the potential for faster recovery times and less morbidity. Not all therapies are in the pharmacological or surgical arenas. This review also explores the evidence for complementary treatments, including relaxation and meditation techniques, and art and music therapy. Despite the range of antiseizure medications available, they still provide inadequate for a large number of patients with epilepsy, either due to ongoing seizures or intolerable side effects. Complementary therapies, including diet, meditation techniques, and music therapy, provide compelling treatment options to improve quality of life while potentially improving seizure control. In appropriate patients, stimulation devices or surgical resection can offer options for significant seizure reduction or even cure. The full range of therapeutics should be considered for each patient with epilepsy when they are struggling with inadequate seizure control or side effects with traditional pharmacological treatment.