Cerebellar modulation of seizures through the cerebello-thalamo-cortical pathway

项目摘要/摘要 癫痫是一种毁灭性的神经疾病，通常是致命的，表现为一种独立的疾病或AS 在其他使人衰弱的情况下的共病。不幸的是，治疗往往无效，部分原因是 癫痫发作的神经起源尚不清楚。作为识别大脑中癫痫发作轨迹的第一步，我设计了 一种小鼠的光遗传学方法，它提供了一种产生严重癫痫的通用方法。这 这种方法使我能够测试特定的大脑区域是否有能力引发癫痫发作和审问 癫痫发作传播和维持的电路机制。我生成的癫痫模型是 基于控制被称为小脑的大脑区域的神经回路的功能，现在被认为是 它是所有运动功能的中枢，也是越来越多的大脑疾病的中心靶子。有一个广泛的 与癫痫有关的小脑功能障碍的文献：尤其是，它的输出可能会驱动无法控制的 癫痫发作时的运动。利用光遗传学，我已经确定了丘脑的一个小脑接收区， 腹后内侧核(VPM)，作为癫痫发作起始的强大区域。VPM是 小脑和基底节环路的会聚因此可能介导非自主运动 几种疾病。将光脉冲传递给通道视紫红质表达的小鼠的VPM立即引起， 以肌阵挛前肢运动开始的可重复性癫痫发作，进展为严重的全身 抽搐。我测试了VPM作为通过刺激来驱动行为的主要基因座的特异性 并未观察到明显的行为异常。此外，持续时间 而这些光遗传诱发的癫痫的严重程度随着几天的重复刺激而恶化。有趣的是， 这些行为让人想起临床报告，即人类癫痫发作恶化并变得更加频繁。 在第一次暴发之后。我的数据提出了一个耐人寻味的假设，即VPM中有一个离散的神经元池 可能是癫痫发作的支点，小脑在其中提供了强大的刺激作用，控制着 癫痫的严重程度。为了验证这一假设，我将使用小鼠来确定癫痫的病理生理学特征 (AIM1)，测试小脑回路如何与丘脑和其他区域相互作用产生癫痫(AIM2)， 并揭示导致癫痫发作的细胞放电机制(Aim3)。每个目标的实验都将 包括最先进的解剖学和活体生理学技术。这些目标的实现将呼唤 重新评估皮层下结构在癫痫发生中的作用，特别是因为小脑是癫痫发作的 脑深部电刺激治疗癫痫的首个靶点。新的治疗性脑的可用性 抗药性癫痫的靶点将提供替代的医疗考虑，以减少 严重癫痫发作和改善受影响患者的生活质量。

PROJECT SUMMARY/ABSTRACT Seizures are a devastating and often fatal neurological condition that manifests as a standalone disease or as a comorbidity in other debilitating conditions. Unfortunately, treatments are often ineffective, in part because the neural origins of seizures are unclear. As a first step towards identifying seizure loci in the brain, I designed an optogenetic approach in mice that provides a versatile method for generating severe seizures. This approach allows me to test whether specific brain regions have the capacity to initiate seizures and interrogate the circuit mechanisms underlying seizure propagation and maintenance. The seizure model I generated is based on controlling the function of neural circuits in a brain region called the cerebellum, now considered the hub for all motor functions and a central target in a growing list of brain diseases. There is an extensive literature implicating cerebellar dysfunction in epilepsy: in particular, its output may drive the uncontrollable movements during seizures. Using optogenetics, I have identified a cerebellar receiving region of the thalamus, the ventral posteromedial nucleus (VPM), as a powerful region of seizure initiation. The VPM is a major point of convergence of cerebellar and basal ganglia circuitry and could therefore mediate involuntary movements in several diseases. Delivery of light pulses to the VPM in channelrhodopsin-expressing mice elicits immediate, reproducible seizures that begin with myoclonic forelimb movements that progress to severe full body convulsions. I tested the specificity of the VPM as the main locus driving the behavior by stimulating surrounding thalamic nuclei and did not observe obvious behavioral abnormalities. Furthermore, the duration and severity of these optogenetic induced seizures worsens upon repeated stimulation over days. Interestingly, these behaviors are reminiscent of clinical reports that human seizures worsen and become more frequent following the first outbreak. My data raise the intriguing hypothesis that a discrete pool of neurons in the VPM may be a fulcrum site for seizures, into which the cerebellum provides a powerful stimulatory role that controls seizure severity. To test this hypothesis, I will use mice to determine the features of seizure pathophysiology (Aim1), test how cerebellar circuits interact with the thalamus and other regions to generate seizures (Aim2), and uncover the cellular firing mechanisms that produce seizures (Aim3). The experiments in each aim will include state-of-the-art anatomical and in vivo physiological techniques. The completion of these aims will call for a reevaluation of subcortical structures in seizure genesis, especially since the cerebellum was one of the first targets for deep brain stimulation in the treatment of epilepsy. The availability of new therapeutic brain targets for drug-resistant epilepsy will provide alternate healthcare considerations for reducing the impact of severe seizures and improving the quality of life of affected patients.