Multiple climbing fiber innervation of Purkinje cells in the adult cerebellum

成人小脑浦肯野细胞的多重攀爬纤维神经支配

• 批准号: 10315621
• 负责人: Christian Robert Hansel
• 金额: $ 45.1万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2023-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10315621
• 关键词: Address; Adult; Age; Anatomy; Animals; Architecture; Auditory; Behavioral; Brain; Calcium; Calcium Signaling; Cells; Cerebellum; Characteristics; Complex; Confocal Microscopy; Contralateral; Data; Dendrites; Development; Dyes; Electrophysiology (science); Elements; Evolution; Excitatory Synapse; Exposure to; Female; Fiber; Flowcharts; Fluorescent Dyes; Frequencies; Funding; Goals; Image; In Vitro; Individual; Inferior; Injections; Instruction; Investigation; Knowledge; Label; Laboratories; Learning; Location; Measures; Methodology; Microscopic; Minority; Modality; Morphology; Motor; Mus; Neurons; Olives - dietary; Output; Pattern; Physiology; Pilot Projects; Play; Population; Purkinje Cells; Qualifying; Research; Rewards; Rodent; Role; Sensory; Signal Transduction; Slice; Stains; Stimulus; Subgroup; Synapses; Tactile; Testing; Tracer; Visual; awake; base; cognitive function; in vivo; male; motor control; motor learning; nerve supply; neuronal cell body; operation; patch clamp; response; sensory stimulus; sex; supervised learning; theories; two-photon

The architecture of brain circuits plays an essential role in understanding their function. The discovery of principal concepts in physiology and neurocomputation critically depends on the availability of precise morphological knowledge. A prominent example supporting this notion is the cerebellum, a brain circuit that is involved in motor (and non-motor) control and adaptation. At the center of cerebellar circuits are Purkinje cells, projection neurons that receive thousands of excitatory synapses, which convey sensory information needed for proper motor control. A hallmark feature of these unique neurons is that they have a massive dendrite that is innervated, in the adult brain, by one climbing fiber input. The climbing fiber plays a crucial role in theories of cerebellar supervised learning, and within this conceptual framework provides an instructive signal (here an error signal) guiding plasticity at parallel fiber synapses. More recent studies have, in addition, pointed out roles in reward signaling and noted that climbing fiber-evoked complex spikes occur in response to a variety of sensory stimuli and may also carry motor command signals. These activity-dependent complex spikes are observed in addition to spontaneous complex spikes that occur at an average frequency of about 1Hz. Thus, while we do not know what the exact functions of climbing fiber signaling are, it is obvious that this unusual input provides a core element of cerebellar cortical circuits and to some degree will define its operations. Our discovery – presented here as pilot data – that a subgroup of the entire adult Purkinje cell population (~15%) has two climbing fiber inputs instead of just one, that two inputs are almost exclusively observed in Purkinje cells with two primary dendrites (either separately exiting from the soma, or separating in close proximity to it) and that within this subgroup 20-25% of Purkinje cells show two climbing fiber inputs, leads to the question whether there is a functional significance of this double innervation. Is persistent double climbing fiber innervation of adult Purkinje cells a bug or a feature? In this exploratory study, we plan to examine the basic phenomenon further and to assess whether two separate climbing fiber inputs may signal independently. If the answer to our ‘bug or feature’ question is ‘feature’, we will examine consequences for cerebellar function (e.g. behavioral learning tests) in subsequent studies that we will seek separate funding for. The first aim uses patch-clamp recordings from mice in combination with confocal microscopy in vitro to test the hypothesis that the persistence of multiple climbing fibers is not random, but occurs in Purkinje cells with two primary dendrites. We will also inject tracer dyes into the inferior olive to stain climbing fibers and anatomically confirm the existence of two climbing fiber inputs. The second aim will add calcium imaging in vitro to examine whether a double climbing fiber input leads to functionally separate, dendritic calcium signaling domains. The third aim uses GCaMP6f-based two-photon imaging from Purkinje cells in awake mice to assess whether under spontaneous conditions, or with sensory stimulation, two climbing fiber inputs may operate independently.

大脑回路的结构对于理解其功能起着至关重要的作用。 生理学和神经计算中的主要概念关键取决于精确的可用性 支持这一概念的一个突出例子是小脑，它是一个大脑回路。 参与运动（和非运动）控制和适应的小脑回路的中心是浦肯野细胞， 接收数千个兴奋性突触的投射神经元，传递所需的感觉信息 这些独特神经元的一个标志性特征是它们具有巨大的树突，可以实现适当的运动控制。 在成人大脑中，由一种攀爬纤维输入支配攀爬纤维在理论中起着至关重要的作用。 小脑监督学习，并在这个概念框架内提供了一个指导性信号（这里是一个 此外，最近的研究还指出，误差信号）引导平行纤维突触的可塑性。 在奖励信号传导中的作用，并指出攀爬纤维诱发的复杂尖峰响应于各种 这些依赖于活动的复杂尖峰是感觉刺激，也可能携带运动命令信号。 除了以约 1Hz 的平均频率出现的自发复杂尖峰之外，还观察到了这样的情况： 虽然我们不知道攀爬纤维信号的确切功能是什么，但很明显，这种不寻常的信号 输入提供了小脑皮质回路的核心要素，并在某种程度上决定了其运作。 发现 - 此处作为试点数据提供 - 整个成年浦肯野细胞群的一个亚群（~15%） 有两个攀爬纤维输入而不是只有一个，这两个输入几乎只在浦肯野观察到 具有两个初级树突的细胞（分别从体细胞中退出，或在紧邻体细胞的地方分离） 在这个亚组中，20-25% 的浦肯野细胞显示出两种攀爬纤维输入，这就引出了一个问题 持久的双攀爬纤维是否存在这种双神经支配的功能意义。 成年浦肯野细胞的神经支配是缺陷还是特征？在这项探索性研究中，我们计划检查 进一步基本现象并评估两个单独的攀爬纤维输入是否可以独立发出信号。 如果我们的“错误或功能”问题的答案是“功能”，我们​​将检查小脑功能的后果 （例如行为学习测试）在我们将寻求单独资助的后续研究中。 小鼠膜片钳记录与体外共聚焦显微镜相结合，以检验以下假设： 多个攀爬纤维的持续存在不是随机的，而是发生在具有两个初级纤维的浦肯野细胞中 我们还将向下橄榄注射示踪染料以染色攀缘纤维并进行解剖学确认。 第二个目标是在体外添加钙成像来检查是否存在两种攀爬纤维输入。 双攀爬纤维输入导致功能独立的树突状钙信号传导域。 使用来自清醒小鼠浦肯野细胞的基于 GCaMP6f 的双光子成像来评估是否处于 自发条件或感官刺激下，两个攀爬纤维输入可以独立运行。