Linking function, structure, and molecular identity of lateral habenula neurons

摘要： 外侧缰核(LHb)通过密集的直接和间接投射向中脑影响动机行为 多巴胺能和5-羟色胺能神经元。一些LHb神经元直接投射到中脑多巴胺能或 5-羟色胺能神经元；其他通过多种类型的中脑GABA能神经元中的一种间接投射。 与多巴胺能神经元类似，LHb编码奖励预测误差(RPE)--两者之间的差异 期望值和实际值-一个强大的计算，指导从环境反馈中学习。然而， 在LHb中有大量的分子和解剖异质性，目前还不清楚如何奖励 具有不同投射靶点、亚核位置和分子的LHb神经元的编码不同 配置文件。在这里，我们建议开发将体内信息编码、投射靶点 单个LHb神经元的亚核定位和分子表达特性-从而描绘出功能， LHb神经元的多模式分类，以更好地了解LHb的组织。我们假设一个 LHb神经元功能类别的子集编码RPE，更广泛地说，编码体内不同的活动 图案映射到具有不同投射目标、亚核位置和分子轮廓的神经元上。在AIM 1，我们将优化GRIN透镜成像方法，以增加可成像的LHb神经元的数量 同时。我们还将开发一种无毒的狂犬病病毒系统用于对LHb进行功能成像 小鼠具有不同细胞类型特异性中脑投射的神经元。在目标2中，我们将验证用于 在活体成像的脑片中识别单个LHb神经元。这些方法将允许我们指定 在行为正常的小鼠身上功能成像的神经元的分子分类和亚核位置，以及 与目标1一起，链接体内信息编码、投射靶点、亚核位置和分子 单个LHb神经元的表达特性。此外，目标2中提出的实验将证明- 对于其他旨在了解不同细胞类型功能的研究(特别是 是由多个分子标记定义的)--理解神经复杂性的关键一步 系统。

ABSTRACT: The lateral habenula (LHb) impacts motivated behavior through dense direct and indirect projections to midbrain dopaminergic and serotonergic neurons. Some LHb neurons project directly to midbrain dopaminergic or serotonergic neurons; others project indirectly through one of multiple types of midbrain GABAergic neurons. Similar to dopaminergic neurons, the LHb encodes reward prediction error (RPE) - the discrepancy between expected and actual value – a powerful computation that guides learning from environmental feedback. However, there is a large amount of molecular and anatomical heterogeneity in the LHb, and it is unclear how reward encoding varies among LHb neurons with different projection targets, subnuclear location, and molecular profiles. Here we propose to develop methods that would link in vivo information encoding, projection target, subnuclear location, and molecular expression properties of individual LHb neurons – thus delineating functional, multimodal classes of LHb neurons to better understand the organization of the LHb. We hypothesize that a subset of functional classes of LHb neurons encodes RPE, and more generally, that distinct in vivo activity patterns map onto neurons with different projection targets, subnuclear location, and molecular profiles. In Aim 1, we will optimize our GRIN lens imaging methods to increase the number of LHb neurons that can be imaged simultaneously. We will also develop the use of a non-toxic rabies virus system for functionally imaging LHb neurons with different cell-type-specific midbrain projections in mice. In Aim 2, we will validate methods for identifying individual LHb neurons in brain slices that were imaged in vivo. These methods will allow us to specify the molecular class and subnuclear location of neurons that were functionally imaged in behaving mice, and together with Aim 1, link in vivo information encoding, projection target, subnuclear location, and molecular expression properties of individual LHb neurons. Moreover, the experiments proposed in Aim 2 would be proof- of-principle for other studies that aim to understand the function of different cell types (especially cell types that are defined by multiple molecular markers) – a critical step for making sense of the complexity of the nervous system.