Coordination of M1 projection neuron subtypes by oscillations

项目摘要/摘要 运动动作，如伸展，通常依靠初级运动皮质(M1)来执行。振荡 M1中的活动伴随着运动动作，与这些动作相关的主要脑电活动 作为事件相关去同步化(ERD)，运动开始时的低频能量损失。 人类、猴子和啮齿动物的脑内记录发现，ERD与运动同时发生 M1中的相关伽马振荡。伽玛作为一种治疗靶点受到了越来越多的关注，因为 在几种运动障碍中，它会发生改变，并受到经颅刺激的影响。然而，微电路 而对M1中伽马振荡作用的研究还不够深入。鉴于专业预测的丰富性 对于M1中的神经元，了解正常受试者中伽马是如何协调它们的是至关重要的。在其他皮质中 电路，伽马振荡取决于主细胞(PN)和快速尖峰之间的相互作用 中间神经元(FSIS)。在M1中，投影特定的PN亚型与FSIS的连接性不同，这表明 它们受到伽马的不同调节。这个项目试图理解伽马振荡是如何在 REACH能协调M1的三大类PNS：锥体束、皮质纹状体和皮质丘脑。在……里面 目的1.在大鼠熟练的触达任务中记录M1的局部场电位和单单位活动。 细胞外尖峰波形特征将被用来识别FSIS，而PNS将被分类为 逆行刺激。将跟踪爪子的运动学以测量伸展。对于每个PN子类型，我们将 表征对伽马的夹带，与FSIS的协调，以及达到相关。目标2剖析电路 伽马夹带中任何投影特定差异的潜在机制。对于每一对PN子类型， 一种是选择性地表达Chrome中的兴奋性视蛋白，另一种是用绿色荧光蛋白标记。 在M1脑片上，将在伽马诱导期间对两个种群进行全细胞膜片钳记录 通过光基因斜坡刺激。这将揭示携带视蛋白的人群诱导局部伽马的能力， 以及GFP人群对此有多敏感。电压钳记录将揭示出 EPSCs和IPSCs到这些节律，进一步阐明了电路机制。最后，目标3评估了 伽马夹带的行为重要性。到达任务过程中的闭环光遗传调制 每个PN亚型都将与正在进行的M1伽马同步或异相地偏置其尖峰。 这对伽马幅度、行为表现和非刺激投影PNS的影响将是 下定决心。总而言之，这些目标提供了M1伽马如何协调 输出微电路，阐明其生理，并测试其行为相关性。这些洞察力对于 加深我们对M1和运动性障碍振荡活动的理解，并完善未来的治疗方法。

PROJECT SUMMARY/ABSTRACT Motor acts such as reaching often rely upon the primary motor cortex (M1) for their execution. Oscillatory activities in M1 accompany motor actions, with the dominant electroencephalographic correlate of those actions being event-related desynchronization (ERD), a loss of low frequency power during movement onsets. Intracerebral recordings in humans, monkeys, and rodents have found that ERD co-occurs with movement associated gamma oscillations in M1. Gamma has received increased attention as a therapeutic target because it is altered in several movement disorders and affected by transcranial stimulation. However, the microcircuitry and function of gamma oscillations in M1 are not well studied. Given the abundance of specialized projection neurons in M1, it is crucial to understand how they are coordinated by gamma in normal subjects. In other cortical circuits, gamma oscillations depend on the interaction between principal cells (PNs) and fast-spiking interneurons (FSIs). In M1, projection-specific PN subtypes differ in their connectivity with FSIs, suggesting that they are differentially regulated by gamma. This project seeks to understand how gamma oscillations during reaching orchestrate three major classes of PNs in M1: pyramidal tract, corticostriatal, and corticothalamic. In Aim 1, local field potentials and single unit activity in M1 are recorded during a skilled reaching task in rats. Extracellular spike waveform characteristics will be used to identify FSIs, while PNs will be classified with antidromic stimulation. Paw kinematics will be tracked to measure reaching. For each PN subtype, we will characterize entrainment to gamma, coordination with FSIs, and reaching correlates. Aim 2 dissects the circuit mechanisms underlying any projection-specific differences in gamma entrainment. For each pair of PN subtypes, one will be made to selectively express the excitatory opsin ChroME, while the other will be labeled with GFP. In M1 brain slices, whole-cell patch clamp recordings will be made from both populations during gamma induced by optogenetic ramp stimuli. This will reveal the ability for the opsin-bearing population to induce local gamma, and how sensitive the GFP population is to it. Voltage clamp recordings will reveal the relative contributions of EPSCs and IPSCs to these rhythms, further illuminating circuit mechanisms. Lastly, Aim 3 assesses the behavioral importance of gamma entrainment. During the reaching task closed-loop optogenetic modulation of each of the PN subtypes will be delivered to bias their spiking either in- or out-of-phase with ongoing M1 gamma. The effect this has on gamma amplitude, behavioral performance, and the unstimulated projection PNs, will be determined. Altogether, these aims offer a comprehensive characterization of how M1 gamma coordinates the output microcircuitry, clarifies its physiology, and tests its behavioral relevance. Those insights are necessary for deepening our understanding of oscillatory activities in M1 and motor disordes, and perfecting future therapies.