Determining the role of the Cuneate nucleus in the processing of proprioceptive information in the awake behaving animal

项目总结 失去本体感觉的患者证明了理解的必要性 这种意义解释了运动系统是如何协调灵活运动的。一个 理解任何感觉系统的重要方面是进行一系列的转换 在从简单的受体到皮质中丰富而有用的表示的过程中。在 在本体感觉的情况下，对加工的早期阶段的知识知之甚少。这个 大脑中第一个本体感受性突触位于楔状核(CN)。值得注意的是，编码 在非麻醉动物中，从未研究过单个CN神经元对肢体状态的影响 之前，尽管行为电生理学在其他大脑区域已经有50年的历史。我提议 从CN记录清醒的猴子的行为，以确定本体感觉是如何编码的 在这个低层区域。 两个主要的感受器类别包括本体感觉：肌梭和高尔基体 肌腱器官分别编码肌肉长度和力量。以前的实验 对CN的调查得出了关于信号汇聚的相互矛盾的结果 从多个肌肉和受体类型来看，矛盾可能可以用 麻醉。麻醉抑制了大脑皮层的活动，这已被证明是发送下行 向包括CN在内的脑干核团发出信号。此外，研究人员还调查了 在本体感觉信号传递上的麻醉发现了衰减的证据 在手术镇静状态下肌肉传入。通过学习清醒状态下的CN，我将 去除这些影响以更好地了解空间和通道融合的程度 以及下行输入对其传递的影响。 本体感觉信息。 我将进行实验，以回答三个目标。首先，我将测试麻醉对 本体感觉在猕猴中央核单个神经元中的表达。有选择性地 受体刺激，我将表征在中脑核内神经元的反应性 清醒和麻醉状态。第二，使用选择性受体刺激和编码 CN神经元的模型，我将测试CN中的单个神经元如何在 触达行为。第三，我将比较CN如何代表活跃产生的运动 那些由外部扰动产生的，并试图在CN中找到传出副本。 通过这些目标，我将回答关于CN在传入中的作用的基础性问题 本体感觉通路。

PROJECT SUMMARY Patients who have lost the sense of proprioception demonstrate the necessity of understanding this sense in explaining how the motor system is able to coordinate dexterous movements. An important aspect in understanding any sensory system is the set of transformations that take place in the pathway from simple receptors to rich and useful representations in cortex. In the case of proprioception, knowledge of the early stages of processing are poorly understood. The first proprioceptive synapse in the brain is in the Cuneate Nucleus (CN). Remarkably, encoding of limb state by single CN neurons has never been examined in a non-anesthetized animal before, despite 50 years of behavioral electrophysiology in other brain areas. I propose to record from the CN of an awake behaving monkey to determine how proprioception is encoded in this low-level area. Two main receptor classes comprise the sense of proprioception; muscle spindles and Golgi tendon organs encode muscle lengths and forces respectively. Previous experiments investigating the CN have yielded contradictory results regarding the convergence of signals from multiple muscles and receptor types, contradictions that may be explained by the effects of anesthesia. Anesthesia suppresses cortical activity, which has been shown to send descending signals to brainstem nuclei including CN. Additionally, studies investigating the effects of anesthesia on transmission of proprioceptive signals have found evidence of attenuation of muscle afferents while under surgical sedation. By studying the CN in the awake state, I will remove these effects to better understand both the extent of spatial and modality convergence of neurons in CN, as well as the effects of descending inputs on its transmission of proprioceptive information. I will conduct experiments which answer three aims. First, I will test the effect of anesthesia on the representation of proprioception in single neurons of the CN of a monkey. With selective receptor stimulation, I will characterize the responsiveness of neurons in the CN in both the awake and anesthetized states. Second, using the selective receptor stimulation and encoding models of CN neurons, I will test how single neurons in the CN represent information during reaching behavior. Third, I will compare how the CN represents actively generated movements to those generated by external perturbation, with an attempt to find efference copy in CN. Through these aims, I will answer foundational questions about the role of CN in the afferent proprioceptive pathway.