About 5% to 10% of epileptic patients suffer from Juvenile Myoclonic Epilepsy (JME), which is characterized by spasms of the arms, ataxia (uncoordinated movements), and general tonic-clonic seizures. In a recent study, a group of patients with myoclonic epilepsy was found to harbor mutations in the PRICKLE1 and PRICKLE2 genes. This suggested that PRICKLE genes might be linked to epilepsy, and given that PRICKLE is highly evolutionarily conserved (including in fruit flies), we decided to use Drosophila in order to determine, first, whether flies with prickle mutations were seizure-prone, and if so, to then use the powerful genetic tools of Drosophila to elucidate the underlying mechanism of the prickle-associated epilepsy. In this work, we show that mutation of the pksple isoform (one of the two adult prickle isoforms in flies) lowers the seizure threshold in the mutant flies (resulting in seizure activity), while mutation of the other adult isoform, pkpk, had no effect. This was demonstrated through both behavioral assays (where the pksple mutant flies showed a reduction in recovery of climbing behavior after being subjected to mechanical stimulation while the pkpk mutant flies did not) as well as electrophysiological analysis (where pksple mutants were shown to be hyperexcitable after electrical stimulation, while the pkpk allele showed no change in spiking activity). We demonstrated that the underlying mechanism of the hyperexcitability seen in the pksple flies was due to enhanced anterograde transport on microtubule (MT) tracks in neurons, the main route for transport in neurons, which could be suppressed by reducing the dose of either of two Kinesin motor proteins, the motors involved in anterograde transport in neurons. On the other hand, the pkpk mutants showed the reverse effect, exhibiting a significant reduction in vesicle transport dynamics. We showed that microtubule polarity could be partially reversed by tipping the balance of the pk isoforms similar to what is seen in the pkpk mutants (such that a large percentage of MTs now had their plus ends oriented towards the cell body, which is extremely rare in axons), suggesting that the vesicle transport defects seen in the pkpk mutants might be due to mixed polarity of MTs. Next, we showed that the seizure-prone pksple mutants, but not the pkpk mutants, exhibited a myoclonic form of epilepsy, as well as abnormal walking patterns and uncoordinated movements, paralleling the ataxia phenotype seen in the epileptic patients with PRICKLE mutations. These data suggest that the primary aspects of the epilepsy-ataxia syndrome seen in patients with PRICKLE mutations are recapitulated in flies, which underscores the utility of using the fruit fly genetic system to model this disorder. Finally, our preliminary results suggest that the pk alleles have different effects on neuronal morphology due to changes in sizes of terminal boutons at the neuromuscular junction (NMJ) in larvae. These data suggest that pk is having a direct effect on synaptic formation and likely function. In conclusion, by using our Drosophila model system, we were able to link prickle mutations to epilepsy as well as identify the cellular mechanism of the prickle-associated epilepsy, a novel epilepsy mechanism previously associated with neurodegeneration. To our knowledge, this is the first example of a gene that, when mutated, will cause seizures in flies, zebrafish, mice, and humans, indicating that the role of prickle in controlling seizure activity is remarkably conserved in animals. Significantly, since about one third of patients with epilepsy do not respond to current AEDs, our fly model and the techniques we have developed will enable us to conduct drug screens for testing potential chemical compounds as new AEDs.

Only a few of the widely used medications used to treat seizures are approved by the FDA for use in children. Your doctor can tell you the details of your child's specific medication including the indications for use and its safety profile. Learn more here.

There is a complex relationship between genetic mutations and their phenotypic expression. Two patients who carry the exactly same disease-causing mutation can have drastically different severity in disease symptoms. Such phenotypic variations may be due to environmental factors, such as diet, stress and temperature, as well as genetic variations, including single nucleotide polymorphisms and copy number variations in other loci. From a clinical point of view, the environmental and genetic factors that modify phenotypic severity are important because, even when we cannot correct the original mutations, it may be able to reduce the burden of genetically inherited disorders by manipulating these modifiers. To study environmental and genetic modifiers, we used Shudderer (Shu), a Drosophila mutant for the voltage-gated sodium (Nav) channel gene, as an experimental model. Nav channels are essential for generation and propagation of action potentials in neurons. Reflecting their functional importance in neural function, mutations in the Nav channel genes are associated with a variety of human neurological disorders. Shu mutants display severe behavioral defects (e.g., spontaneous jerking and heat-induced seizures) and morphological abnormalities (e.g., indented thorax and down-turned wings). The goal of this study was to identify and characterize the environmental and genetic factors that modify behavioral and morphological phenotypes of Shu mutants. For environmental modifiers, we serendipitously discovered that a diet supplemented with milk dramatically reduces the Shu phenotypes. To identify genetic modifiers, we took two independent approaches, microarray analysis and unbiased forward genetic modifier screening. We found that reduction of Gadd45 or GstS1 activity leads to suppression of the Shu phenotypes to different degrees. Intriguingly, the effects of these genetic and environmental modifiers apparently converge into enhancement of the GABAergic inhibitory system. Because the molecular and cellular mechanisms underlying the basic neurobiological processes are highly conserved between flies and humans, our findings are expected to provide fundamental insights into genetic and environmental modifiers for human Nav channel gene mutations, leading to the future development of novel strategies for preventing and treating disorders caused by dysfunctional Navchannels.

Neurological disorders, such as epilepsy, often result from inherited or newly acquired genetic mutations. However, individuals possessing the exact same disease-causing mutations can exhibit dramatic differences in the severity of their symptoms. These differences can be explained in part by environmental factors, such as the microbes in our gut, that play an important role in the manifestation of disease symptoms. Within the last decade, microbes living in the gut have established themselves as an environmental factor with profound effects on our health and well-being. Of special interest is the relationship between the gut microbiota and neurological disease. The goal of my thesis was to: 1) characterize the gut microbiota composition and 2) understand how the gut microbiota modulates seizure-like behavior using Shudderer, a fruit fly (Drosophila melanogaster) model of epilepsy. Shudderer flies possess a mutation in the voltage-gated sodium channel gene and display seizure-like behavioral abnormalities including spontaneous tremors and heat-induced seizures. We identified differences in the microbial composition of the gut microbiota between Shudderer and control (healthy) flies. We also found that by removing the gut microbiota we could improve seizure-like behavior of Shudderer flies as well as another Drosophila mutant harboring a similar genetic mutation. Together, these findings provide evidence that a bidirectional interaction exists between the gut microbiota and neurological function. Since the molecular and cellular mechanisms controlling basic biological processes are highly conserved between fruit flies and humans, these findings are expected to be applicable to mammalian systems, including humans, and may lead to the future development of novel therapeutics to treat epilepsy and other neurological disorders.

Amygdala kindling is commonly used to study the neural mechanisms of temporal lobe epilepsy and its behavioral consequences. The repetitive seizure activity that occurs during kindling is thought to induce an extensive array of structural and functional modifications within the brain, particularly in the hippocampus and dentate gyrus regions. Some of these changes include the growth or sprouting of new axonal connections as well as the birth and integration of new neurons into hippocampal circuits. Previous work has shown that these changes in structural and functional plasticity are not necessarily beneficial events. For instance, the growth and reorganization of synaptic terminals in the hippocampus and other brain regions might serve as a substrate that enhances hyperexcitability and seizure generation. In addition, although seizures induce the birth of new neurons, many of these newly generated cells migrate and function improperly within the hippocampal networks. Considering the prominent role of the hippocampus in a variety of behaviours, including learning, memory, and mood regulation, it would appear that alterations involving the structural and functional properties of both mature and newly born neurons in this region could impact these hippocampal-dependent functions. However, to date, the role of kindling-induced changes in hippocampal structural plasticity and neurogenesis on behaviour is incomplete, and the molecular mechanisms that govern these pathological events are poorly understood.<p/> The aim of this dissertation is to gain a better understanding of the changes in synaptic plasticity and neurogenesis within the hippocampus that occur after amygdala kindling. In chapter 2, we will examine if kindling alters the expression of synapsin I, a molecular marker of synaptic growth and activity, in both the hippocampus and other brain regions. In addition, we will also set out to determine if changes in synapsin I are related to the development of behavioural impairments associated with kindling. In chapter 3, the effect of kindling on hippocampal neurogenesis will be examined. In addition, we will also evaluate the effect of kindling on the expression of Reelin and Disrupted-in-Schizophrenia 1 (DISC1), two proteins instrumental for mediating proper neuronal migrational and maturation during development. In chapter 4, the effect of altered DISC1 expression in the dentate gyrus after kindling will be examined more extensively. We will examine whether altered DISC1 expression in the dentate contributes to some of the pathological features associated with seizure-induced hippocampal neurogenesis, such as ectopic cell migration and dentate granule cell layer dispersion. Finally, in chapter 5, the impact of aberrant seizure-induced neurogenesis on behaviour will be examined by determining if seizure-generated neurons functionally integrate and participate in hippocampal circuits related to memory processing. The results of this dissertation enhances our understanding of the functional consequences that altered hippocampal synaptic plasticity and neurogenesis may have on the development of epilepsy and emergence of cognitive impairments associated with chronic seizures.<p/>

Amygdala kindling is commonly used to study the neural mechanisms of temporal lobe epilepsy and its behavioral consequences. The repetitive seizure activity that occurs during kindling is thought to induce an extensive array of structural and functional modifications within the brain, particularly in the hippocampus and dentate gyrus regions. Some of these changes include the growth or sprouting of new axonal connections as well as the birth and integration of new neurons into hippocampal circuits. Previous work has shown that these changes in structural and functional plasticity are not necessarily beneficial events. For instance, the growth and reorganization of synaptic terminals in the hippocampus and other brain regions might serve as a substrate that enhances hyperexcitability and seizure generation. In addition, although seizures induce the birth of new neurons, many of these newly generated cells migrate and function improperly within the hippocampal networks. Considering the prominent role of the hippocampus in a variety of behaviours, including learning, memory, and mood regulation, it would appear that alterations involving the structural and functional properties of both mature and newly born neurons in this region could impact these hippocampal-dependent functions. However, to date, the role of kindling-induced changes in hippocampal structural plasticity and neurogenesis on behaviour is incomplete, and the molecular mechanisms that govern these pathological events are poorly understood.<p/> The aim of this dissertation is to gain a better understanding of the changes in synaptic plasticity and neurogenesis within the hippocampus that occur after amygdala kindling. In chapter 2, we will examine if kindling alters the expression of synapsin I, a molecular marker of synaptic growth and activity, in both the hippocampus and other brain regions. In addition, we will also set out to determine if changes in synapsin I are related to the development of behavioural impairments associated with kindling. In chapter 3, the effect of kindling on hippocampal neurogenesis will be examined. In addition, we will also evaluate the effect of kindling on the expression of Reelin and Disrupted-in-Schizophrenia 1 (DISC1), two proteins instrumental for mediating proper neuronal migrational and maturation during development. In chapter 4, the effect of altered DISC1 expression in the dentate gyrus after kindling will be examined more extensively. We will examine whether altered DISC1 expression in the dentate contributes to some of the pathological features associated with seizure-induced hippocampal neurogenesis, such as ectopic cell migration and dentate granule cell layer dispersion. Finally, in chapter 5, the impact of aberrant seizure-induced neurogenesis on behaviour will be examined by determining if seizure-generated neurons functionally integrate and participate in hippocampal circuits related to memory processing. The results of this dissertation enhances our understanding of the functional consequences that altered hippocampal synaptic plasticity and neurogenesis may have on the development of epilepsy and emergence of cognitive impairments associated with chronic seizures.<p/>

<p>Understanding the mechanisms of limbic epileptogenesis in cellular and molecular terms may provide novel therapeutic targets for its prevention. The neurotrophin receptor tropomyosin-related kinase B (TrkB) is thought to be critical for limbic epileptogenesis. Enhanced activation of TrkB, revealed by immunodetection of enhanced phosphorylated TrkB (pTrkB), a surrogate measure of its activation, has been identified within the hippocampus in multiple animal models. Knowledge of the cellular locale of activated TrkB is necessary to elucidate its functional consequences. Using an antibody selective to pTrkB in conjunction with confocal microscopy and cellular markers, we determined the cellular and subcellular locale of enhanced pTrkB induced by status epilepticus (SE) evoked by infusion of kainic acid into the amygdala of adult mice. SE induced enhanced pTrkB immunoreactivity in two distinct populations of principal neurons within the hippocampus--the dentate granule cells and CA1 pyramidal cells. Enhanced immunoreactivity within granule cells was found within mossy fiber axons and giant synaptic boutons. By contrast, enhanced immunoreactivity was found within apical dendritic shafts and spines of CA1 pyramidal cells. A common feature of this enhanced pTrkB at these cellular locales is its localization to excitatory synapses between excitatory neurons, presynaptically in the granule cells and postsynaptically in CA1 pyramidal cells. Long-term potentiation (LTP) is one cellular consequence of TrkB activation at these excitatory synapses that may promote epileptogenesis.</p><p>The importance of TrkB in diverse neuronal processes, as well as its involvement in various disorders of the nervous system, underscores the importance of understanding how it is activated. The canonical neurotrophin ligand which activates TrkB is brain derived neurotrophic factor (BDNF). Zinc, however, has also been demonstrated to activate this receptor through a mechanism whereby it does not directly interact with it, known as transactivation. Presynaptic vesicles of mossy fiber boutons of stratum lucidum are particularly enriched in zinc, where it is co-released with glutamate in an activity dependent fashion, and incorporated into these vesicles by the zinc transporter, ZnT3. Given the presence of large quantities of zinc within stratum lucidum, we hypothesized that this metal may contribute to TrkB transactivation at this locale. To this end, we examined the contributions of both BDNF and synaptic vesicular zinc to TrkB activation in stratum lucidum of mouse hippocampus under physiological conditions. Utilization of mice which are genetic knockouts for BDNF and/or ZnT3 allowed us to examine TrkB activation in the absence of one or both of these ligands. This was done using an antibody for pTrkB in conjunction with confocal microscopy, assaying immunoreactivity at the cellular and synaptic locales within stratum lucidum where pTrkB was previously found to be enriched. Our results suggest that BDNF contributes to TrkB activation within stratum lucidum. Interestingly, ZnT3 mice displayed an increase in BDNF protein and TrkB activation, demonstrating that synaptic zinc regulates BDNF and TrkB signaling at this locale.</p> / Dissertation

No description available.

abstract: Epilepsy is a chronic illness impacting the lives of over 300,000 children nationally. Sexson and Madan-Swain offer a theory that addresses successful school reentry in children that are chronically ill. Their theory posits that successful school reentry is influenced by school personnel with appropriate attitudes, training experiences, and by factors relating to the child's illness. The parents of 74 students, between second and twelfth grades, completed a questionnaire addressing their child's epilepsy and their current level of seizure control. Each child's homeroom teacher also completed a survey regarding their training experiences about epilepsy and their attitudes towards individuals with epilepsy. Additional information was gathered from the child's school regarding attendance rates, most recent Terra Nova test scores (a group achievement test), and special education enrollment status. Data were analyzed via four multiple regression analyses and one logistic regression analysis. It was found that seizure control was a significant predictor for attendance, academic achievement (i.e., mathematics, writing, and reading), and special education enrollment. Additionally, teachers' attitudes towards epilepsy were a significant predictor of academic achievement (writing and reading) and special education enrollment. Teacher training experience was not a significant predictor in any of the analyses. / Dissertation/Thesis / Ph.D. Educational Psychology 2011

abstract: Epilepsy is a group of disorders that cause seizures in approximately 2.2 million people in the United States. Over 30% of these patients have epilepsies that do not respond to treatment with anti-epileptic drugs. For this population, focal resection surgery could offer long-term seizure freedom. Surgery candidates undergo a myriad of tests and monitoring to determine where and when seizures occur. The “gold standard” method for focus identification involves the placement of electrocorticography (ECoG) grids in the sub-dural space, followed by continual monitoring and visual inspection of the patient’s cortical activity. This process, however, is highly subjective and uses dated technology. Multiple studies were performed to investigate how the evaluation process could benefit from an algorithmic adjust using current ECoG technology, and how the use of new microECoG technology could further improve the process. Computational algorithms can quickly and objectively find signal characteristics that may not be detectable with visual inspection, but many assume the data are stationary and/or linear, which biological data are not. An empirical mode decomposition (EMD) based algorithm was developed to detect potential seizures and tested on data collected from eight patients undergoing monitoring for focal resection surgery. EMD does not require linearity or stationarity and is data driven. The results suggest that a biological data driven algorithm could serve as a useful tool to objectively identify changes in cortical activity associated with seizures. Next, the use of microECoG technology was investigated. Though both ECoG and microECoG grids are composed of electrodes resting on the surface of the cortex, changing the diameter of the electrodes creates non-trivial changes in the physics of the electrode-tissue interface that need to be accounted for. Experimenting with different recording configurations showed that proper grounding, referencing, and amplification are critical to obtain high quality neural signals from microECoG grids. Finally, the relationship between data collected from the cortical surface with micro and macro electrodes was studied. Simultaneous recordings of the two electrode types showed differences in power spectra that suggest the inclusion of activity, possibly from deep structures, by macroelectrodes that is not accessible by microelectrodes. / Dissertation/Thesis / Doctoral Dissertation Bioengineering 2015