Investigating the role of D1 medium spiny neurons in the induction of perseverative behavior

项目摘要 以侵入性思维和重复行为为特征的强迫症(OCD)是 一种使人衰弱的精神障碍，在美国影响大约2%的成年人。尽管人们对此知之甚少 疾病的病因和病理，许多人类成像研究发现，眼眶前额叶皮质 OFC和纹状体在强迫症患者中过度活跃。根据这些发现，最近从 我们的实验室已经证明，慢性光发生刺激内侧OFC(MOFC)轴突终末 腹内侧纹状体(VMS)诱导重复梳理，并在几天内逐渐增加 刺激。此外，美容不受刺激的限制，持续时间长达2周。 刺激停止，表明OFC-纹状体回路内的可塑性是这种行为的基础。提供 进一步的可塑性证据，活体电生理记录表明纹状体诱发的放电 在慢性刺激的过程中，心率会增加。在纹状体内，多巴胺1型受体表达 中棘神经元(d1-msn)是这种持续性机制的一个很好的候选者。 打扮一下。使用SKF化合物，包括部分和全部D1激动剂的治疗，显著增加 异常的梳理行为，而D1受体的全局缺失阻止了SKF诱导的梳理。此外， 我们实验室的初步体内显微内窥镜检查工作表明，D1-MSN钙活性是特异的 SAPAP3基因敲除小鼠在异常梳理行为期间升高，一种表现为强迫症样的模型 强迫性美容表型。因此，我们假设D_1-MSN是诱导 在我们的光遗传系统中的持之以恒的梳理行为。为了检验这一假设，我们将使用 将阐明持之以恒理发的神经基础的技术组合：切片 电生理学、光基因刺激与细胞类型特异性抑制相结合，并依赖于活动 合奏特征。通过这些实验，我们预测：1)将会有选择性增强 慢性刺激mOFC-VMS后d1-msn在皮质纹状体突触中的表达，2)d1-msn的抑制作用减弱 恒久美容的诱导，以及3)恒久美容合奏将包含增加的 D_1-MSN比例。拟议的AIMS将检查mOFC-VMS中细胞类型的特定变化 这是持之以恒的美容表达的基础。这些实验将阐明 皮质纹状体信号功能障碍的机制，这对于促进我们对 强迫症的病理与治疗。此外，还详细分析了D1-MSN在持之以恒行为中的作用 可能会为人体试验提供一个可行的治疗靶点。最后，这项研究计划将使我能够完成我的 神经体外电生理学和活动依赖标记学习技术的培训目标 这将有助于我将强迫症行为障碍作为一种 独立调查员。

PROJECT ABSTRACT Obsessive-compulsive disorder (OCD), which is characterized by intrusive thoughts and repetitive behaviors, is a debilitating mental disorder that affects ~2% of adults in the United States. Although little is known of the cause and pathology of the disease, numerous human imaging studies have found that the orbitofrontal cortex (OFC) and striatum are hyperactive in patients with OCD. In accordance with these findings, recent work from our lab has shown that chronic optogenetic stimulation of medial OFC (mOFC) axon terminals in the ventromedial striatum (VMS) induces repetitive grooming that progressively increases over several days of stimulation. Moreover, grooming is not time-locked to stimulation and persists for up to 2 weeks after stimulation cessation, suggesting that plasticity within the OFC-striatal circuit underlies this behavior. Providing further evidence of plasticity, in vivo electrophysiological recordings demonstrate that the striatal evoked firing rate increases over the course of chronic stimulation. Within the striatum, dopamine type 1 receptor-expressing medium spiny neurons (D1-MSNs) are an excellent candidate for the mechanism of this perseverative grooming. Treatment with SKF compounds, including both partial and full D1 agonists, robustly increases abnormal grooming behavior, while global deletion of D1 receptors prevents SKF-induced grooming. Moreover, preliminary in vivo microendoscopy work from our lab indicates that D1-MSN calcium activity is specifically elevated during abnormal grooming behavior in SAPAP3 knockout mice, a model that exhibits an OCD-like compulsive grooming phenotype. We therefore hypothesize that D1-MSNs underlie the induction of perseverative grooming behavior in our optogenetic system. To test this hypothesis, we will use a combination of techniques that will elucidate the neural basis of perseverative grooming: slice electrophysiology, optogenetic stimulation paired with cell-type specific inhibition, and activity-dependent ensemble characterization. Through these experiments, we predict that: 1) there will be a selective potentiation of D1-MSN corticostriatal synapses after chronic mOFC-VMS stimulation, 2) D1-MSN inhibition will attenuate the induction of perseverative grooming, and 3) perseverative grooming ensembles will contain an increased proportion of D1-MSNs. The proposed aims will examine the cell-type specific changes in mOFC-VMS signaling that underlie the expression of perseverative grooming. These experiments will elucidate the mechanisms of dysfunctional corticostriatal signaling, which is necessary to advance our understanding of OCD pathology and treatment. In addition, detailed analysis of the role of D1-MSNs in perseverative behavior could reveal a viable therapeutic target for human trials. Finally, this research plan will allow me to fulfill my training goals of learning techniques for ex vivo electrophysiology and activity-dependent labeling of neural ensembles, which will facilitate my long-term goal of dissecting compulsive behavioral disorders as an independent investigator.