Functional Striatal Microcircuits in vivo and in vitro

描述（申请人提供）：新纹状体是基底神经节的主要输入结构，该系统不仅对自主运动控制至关重要，而且对强化介导的学习和高级认知功能也至关重要。了解新三叠体功能的重要性可以通过与影响该大脑结构的许多神经和神经精神疾病相关的严重残疾来戏剧性地说明。转基因方法的发展使得基因和功能上不同类型的神经元可视化和靶向化，最近导致了新纹状体中gaba能中间神经元的意外多样性的发现。因此，纹状体现在已知包含至少7种gaba能中间神经元，除了先前已知的快速尖峰（FS）和表达NPY- plts的中间神经元外，还包括4种不同类型的含有酪氨酸羟化酶（TH）的中间神经元和一类新的表达NPY的中间神经元。根据初步数据和早期研究，我们假设新发现的TH和NPY中间神经元是一个高度组织的纹状体内突触回路的重要组成部分，在决定新纹状体的活动和计算功能方面起着重要作用。所提出的研究的目标是了解该电路的突触组织，并评估新发现的中间神经元类别在确定其他组成神经元活动中的功能意义，特别是功能不同类型的投射神经的活动。在体外光遗传学实验中，我们将利用一系列双转基因小鼠来绘制TH和NPY中间神经元的电路组织，在这些双转基因小鼠中，不同类型神经元中Cre-recombinase和EGFP的表达将允许高通量双向分析TH、NPY和FS中间神经元和投射神经元之间的直接和间接通路的连性。TH和NPY中间神经元的功能影响将在小鼠体内光遗传记录实验中进行评估。首先，我们将研究这些中间神经元的放电速率如何随操作性任务的不同阶段而变化。接下来，我们将研究光遗传操作（沉默或激活）TH和NPY中间神经元的活性如何影响投射神经元的放电率，胆碱能

DESCRIPTION (provided by applicant): The neostriatum is the main input structure of the basal ganglia, a system that is crucial not only for voluntary motor control, but also for reinforcement-mediated learning and higher cognitive functions. The importance of understanding the functioning of the nesotriatum is dramatically illustrated by the severe disability associated with numerous neurological and neuropsychiatric conditions that affect this brain structure. Developments in transgenic methods that allow visualization and targeting of genetically and functionally distinct types of neurons has recently led to the discovery of an unexpectedly large diversity of GABAergic interneurons in the neostriatum. As a result the striatum is now known to contain at least 7 types of GABAergic interneurons that include, in addition to the previously known fast spiking (FS) and the NPY expressing NPY-PLTS interneurons, 4 distinct classes of tyrosine hydroxylase (TH) containing interneurons and a new class of NPY expressing interneuron. We hypothesize, based on preliminary data and earlier studies, that the newly discovered TH and NPY interneurons are integral and important constituents of a highly organized intrastriatal synaptic circuitry and play essential roles in determining the activity and computational function of the neostriatum. The goal of the proposed studies is to understand the synaptic organization of this circuitry and to assess the functional significance of the newly discovered interneuron classes in determining the activity of other constituent neurons, in particular, the activity of functionally distinct types of projection neuros. The circuit organization of TH and NPY interneurons will be mapped in in vitro optogenetic experiments using a series of double transgenic mice in which expression of Cre-recombinase and EGFP in distinct types of neurons will allow high-throughput bidirectional analysis of the connectivity among TH, NPY, and FS interneurons and projection neurons of the direct and indirect pathways. The functional impact of TH and NPY interneurons will be assessed in in vivo optogenetic recording experiments in mice trained to perform operant tasks. First, we will examine how the firing rate of these interneurons varies in relation to distinct phases of the operant tasks. Next, we will examine how optogenetic manipulation (silencing or activation) of the activity of TH and NPY interneurons affects the firing rate of projection neurons, cholinergic and FS interneurons, how these manipulations affect local field potential oscillations, and how qualitative or quantitative measures of behavioral performance are affected. These experiments are expected to yield important new insights into the functioning of the neostriatum and may help to identify new cellular substrates for therapeutic interventions in a variety of neurological and neuropsychiatric disorders.