ARX related Interneuron dysfunction and intractable pediatric epilepsy

描述(申请人提供)：早期癫痫脑病是一组以难治性癫痫发作、发育不良和6岁前发病为特征的综合征。作为一名专门研究儿童癫痫的儿童神经科医生，我花了很多临床时间为那些孩子患有这些疾病的家庭提供咨询。我发现这些对话令人沮丧，因为我告诉这些家庭，我们的治疗方法不是为这些疾病设计的，几乎没有指导诊断和治疗的基础研究。迫切需要对早期顽固性癫痫进行进一步研究。如果要在诊断和治疗方面取得进展，开发研究这些综合征的模型是至关重要的。最近，一种发育转录因子--干燥症相关同源盒基因(ARX)的突变被证明会导致X连锁婴儿痉挛综合征和其他早期癫痫脑病。我们的实验表明，中间神经元中Arx的选择性基因缺失(Arx CKO)会导致GABA能中间神经元的异常迁移、脑电活动改变和自发性癫痫发作。这些数据使我们假设，在条件Arx小鼠中，早期中间神经元的丢失改变了正常网络功能的发展，导致难治性癫痫发作和认知功能障碍，模拟了早期癫痫脑病。这一建议既制定了实验，以研究神经元间功能障碍如何导致癫痫和脑病的潜在病理生理过程，也开发了培训机会，以促进我过渡到独立调查人员的职业生涯。为了研究Arx丢失如何导致癫痫发作和智力低下，我首先建议使用电压敏感染料成像技术来确定电路水平功能障碍的程度。接下来，我们将记录和比较对照和Arx CKO突变小鼠在皮质和海马节律期间的脑电和单位活动的发展，以确定节律是如何中断的，以及哪些中间神经元参与其中。这些研究将确定中断神经元间发育是否会改变绑定认知过程的正常节奏。最后，我们将使用一系列行为技术来测试小鼠的认知功能，以提供证据将电路和网络水平的功能障碍与小鼠的认知缺陷联系起来。除了拟议的实验，我还制定了一项计划，帮助我在费城儿童医院和宾夕法尼亚大学工作期间培养过渡到独立所需的技能。从这些研究中，我将学习两种在我未来的工作中实施的技术。这些研究还将建立一个模型的基础，用于了解神经元间发育的变化如何导致早期癫痫脑病。

DESCRIPTION (provided by applicant): The early epileptic encephalopathies are a group of syndromes characterized by intractable seizures, poor developmental outcome, and onset before six years of age. As a child neurologist specializing in pediatric epilepsy, I spend much of my clinical time counseling families whose children have these conditions. I find the conversations to be frustrating as I inform the families that our treatments are not designed for these diseases and little basic research exists to guide diagnosis and treatment. There is a pressing need for further research into the early intractable epilepsies. Developing models to study these syndromes is essential if advances in diagnosis and treatment are to be made. Recently, mutations in the aristaless-related homeobox gene (ARX), a developmental transcription factor, have been shown to cause X-linked infantile spasms syndrome and other early epileptic encephalopathies. Our experiments have shown that selective genetic deletion of Arx in interneurons (Arx CKO) results in abnormal migration of GABAergic interneurons, altered EEG activity, and spontaneous seizures. These data lead us to hypothesize that early loss of interneurons, in conditional Arx mice, alters the development of normal network function leading to intractable seizures and cognitive dysfunction modeling the early epileptic encephalopathies. This proposal both formulates experiments to examine the underlying pathophysiological processes of how interneuron dysfunction leads to seizures and encephalopathy as well as develops training opportunities to facilitate my transition to a career as an independent investigator. To study how Arx loss leads to seizures and mental retardation I first propose to determine the extent of circuit level dysfunction using a voltage sensitive dye imaging technique. Next, we will record and compare the development of control and Arx CKO mutant mice EEG and single unit activity during cortical and hippocampal rhythms to determine how rhythms are interrupted and which interneurons are involved. These studies will ascertain if interrupting interneuronal development alters the normal rhythms that bind cognitive processes. Finally, we will test the cognitive function of the mice, using a battery of behavioral techniques, to provide evidence linking circuit and network level dysfunction to the cognitive deficits of the mice. In addition to the proposed experiments, I have created a plan to help develop the skills needed for my transition to independence while working at the Children's Hospital of Philadelphia and the University of Pennsylvania. From these studies I will learn two techniques to implement in my future work. These studies will also set the foundation of a model to be used to understand how alterations in interneuronal development lead to an early epileptic encephalopathy.