Mechanisms of altered synaptic integration and plasticity underlying cellular and circuit dysfunction in genetic epilepsy disorders

项目总结。突触整合和可塑性是信息传递的细胞学机制。 学习、学习和记忆。这些基本过程在癫痫中是如何被破坏的还不清楚。 全身性癫痫伴发热性惊厥加/Drave型综合征(GEFS/DS)是癫痫的一种表现。 与SCN1B基因突变有关的DES会导致癫痫发作、神经发育迟缓和过早死亡。 为了开发治疗GEFS/DS癫痫发作/认知障碍的方法，迫切需要确定 SCN1B突变扰乱细胞级信息处理和学习的机制。我们的长- 术语的目标是定义将基因与突触整合和可塑性破坏联系在一起的一般原理 神经发育障碍。我们提案的总体目标是定义SYN和SYN之间的相互作用 突触、树突生理学和躯体生理学损害了Scn1b敲打中的突触整合和可塑性。 Out(KO)小鼠模型。我们的中心假设是Scn1b失去调节离子通道和 枝晶的兴奋性、扰动的整体性和可塑性。为了验证这一假设，我们将完成三个目标： 目的1：探讨Scn1b KO神经元的体细胞和树突的高兴奋性机制。 根据初步数据，我们的假设是，Scn1b KO CA1锥体神经元的树突和体细胞都是 RON表现出固有的超兴奋性，部分原因是HCN通道活动异常。我们将检验这一假设 用全细胞、体细胞和树突状细胞记录、免疫组织化学和细胞形态分析。 目的2：探讨Scn1b KO神经元突触整合改变的机制。基于我们的 初步数据，我们的假设是Scn1b的丢失从根本上改变了输入到输出的转换， 时间和空间突触整合异常增强，由于树突的过度兴奋和 破坏了突触的生理学。我们将使用全细胞记录来测试时间和空间特征如何 Scn1b KO神经元的输入/输出功能因突触输入的自然模式而改变。 目的3：验证Scn1b干扰改变突触学习规则和GABA门控的假设 这就决定了可塑性。根据我们的初步数据，我们的假设是，突触学习规则支配着 LTP和LTD诱导由于抑制的兴奋、超兴奋的本征之间的相互作用而重塑 性质，以及Scn1b丢失后异常的去极化抑制所致的异常门控。我们将测试输入如何 在Scn1b丢失后，激发LTP和LTD的模式发生变化，以及抑制如何影响这种可塑性。 在成功完成拟议研究后，我们将确定详细的机制，通过这些机制 神经元内在和突触生理的变化及其相互作用重塑神经的细胞形态 GEFS/DS的Scn1b KO小鼠模型中的加工和学习。这一贡献将提供机械性 遗传变化、主要神经生理学表型和神经元处理缺陷之间的联系- 癫痫发作与GEFS/DS癫痫患者的学习、记忆和认知障碍。

PROJECT SUMMARY. Synaptic integration and plasticity are the cellular mechanisms of information pro- cessing, learning, and memory. How these fundamental processes are disrupted in epilepsy is not understood. Generalized Epilepsy with Febrile Seizures Plus/Dravet syndrome (GEFS+/DS) is a spectrum of epilepsy disor- ders linked to mutations of the SCN1B gene which cause seizures, neurodevelopmental delays, and early death. To develop treatments for seizures/cognitive deficits of GEFS+/DS epilepsies, there is a critical need to identify mechanisms by which SCN1B mutations disrupt cellular-level information processing and learning. Our long- term goal is to define general principles linking genes to disrupted synaptic integration and plasticity in such neurodevelopmental disorders. The overall objective of our proposal is to define how the interplay between syn- apses, dendritic physiology, and somatic physiology impair synaptic integration and plasticity in the Scn1b knock- out (KO) mouse model of GEFS+/DS. Our central hypothesis is loss of Scn1b dysregulates ion channels and dendrite excitability, disturbing integration and plasticity. To test this hypothesis, we will complete three Aims: Aim 1: Determine the mechanisms of somatic and dendritic hyperexcitability in Scn1b KO neurons. Based on preliminary data, our hypothesis is that both dendrites and somata of Scn1b KO CA1 pyramidal neu- rons exhibit intrinsic hyperexcitability in part due to abnormal HCN channel activity. We will test this hypothesis with whole cell somatic and dendritic recordings, immunohistochemistry, and cell morphology analyses. Aim 2: Determine the mechanisms of altered synaptic integration in Scn1b KO neurons. Based on our preliminary data, our hypothesis is that loss of Scn1b fundamentally alters the translation of inputs into outputs, with both temporal and spatial synaptic integration abnormally enhanced due to dendritic hyperexcitability and disrupted synaptic physiology. We will use whole cell recordings to test how temporal and spatial features of input/output functions are altered in Scn1b KO neurons in response to naturalistic patterns of synaptic inputs. Aim 3: Test the hypothesis that Scn1b disruption alters synaptic learning rules and gating by GABA that dictate plasticity. Based on our preliminary data, our hypothesis is that synaptic learning rules governing LTP and LTD induction are re-shaped due to interplay between suppressed excitation, hyperexcitable intrinsic properties, and abnormal gating by aberrant depolarizing inhibition after loss of Scn1b. We will test how input patterns that evoke LTP and LTD shift after loss of Scn1b, and how inhibition influences this plasticity. Upon successful completion of the proposed research, we will have defined detailed mechanisms by which changes in neuron intrinsic and synaptic physiology and their interactions re-shape the cellular forms of neural processing and learning in the Scn1b KO mouse model of GEFS+/DS. This contribution will provide mechanistic links between genetic changes, primary neurophysiology phenotypes, and neuronal processing deficits underly- ing seizures and the learning, memory, and cognition impairments in GEFS+/DS epilepsies.