Chemogenetic afferent modulation to understand spinal cord circuit function and plasticity post injury

化学遗传学传入调制了解脊髓回路功能和损伤后可塑性

• 批准号: 10198063
• 负责人: Andrew Spence
• 金额: $ 39.57万
• 依托单位: TEMPLE UNIV OF THE COMMONWEALTH
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10198063
• 关键词: Affect; Afferent Neurons; Animal Model; Animals; Axon; Behavioral; Caliber; Complex; Coupled; Cutaneous; Data; Data Set; Dissection; Electric Stimulation; Genetic; Goals; Grant; H-Reflex; Histologic; Human; Impairment; Individual; Injury; Interneurons; Lesion; Life; Locomotor Recovery; Mediating; Methods; Modeling; Motor; Motor Neurons; Motor output; Movement; Neurologic; Neuronal Plasticity; Neurons; Neurostimulation procedures of spinal cord tissue; Outcome; Parvalbumins; Patients; Play; Population; Rattus; Recovery; Rehabilitation therapy; Role; Sensory; Spinal; Spinal Cord; Spinal Cord Contusions; Spinal cord injury; Synapses; Tactile; Techniques; Testing; Toes; Tracer; Training; Volition; Walking; Work; base; deep learning; density; designer receptors exclusively activated by designer drugs; effective therapy; feeding; functional plasticity; human model; improved; injury recovery; kinematics; neural circuit; neural network; neuronal excitability; neurophysiology; neuroregulation; novel; novel strategies; recruit; relating to nervous system; selective expression; sensory input; tool; treadmill training; vector

PROJECT SUMMARY Spinal cord injury (SCI) causes life-long neurological impairment, and there is currently no effective treatment. The premise of this proposal is recent work demonstrating that afferent stimulation paired with treadmill training can enhance standing, stepping, and volitional control in humans and animal models. Therefore, it is critically important to understand the mechanisms by which afferent stimulation drives motor improvement. Tools that can identify which afferents are necessary and sufficient to enhance recovery, and that can facilitate characterization of the helpful neural plasticity, are urgently needed. Our long-term goal is to develop approaches for selective afferent modulation, and apply them to the dissection of the mechanisms underlying recovery from SCI. The objective of this grant is to identify which sets of afferents are important for recovery and how spinal circuits change to facilitate it. To achieve selective modulation of afferents and enable genetic tracing we will use Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) that can modulate excitability in specific populations of neurons. To accurately quantify improvement, we will use Deep Learning to analyze large kinematic data sets. Our preliminary data shows strong expression of DREADDs in large diameter DRG neurons, that their activation by CNO can excite or inhibit the H-reflex, and that activation of excitatory DREADDs during treadmill training post-SCI improves stepping. Our main hypothesis is that activation of large afferents by the excitatory DREADD (hM3Dq) during treadmill training will enhance recovery, whereas inhibitory DREADDs (hM4Di) will suppress recovery. Four sub- hypotheses will test whether recovery is mediated by increased afferent projection onto 1) motor neurons, or 2) inhibitory interneurons; or by sprouting of 3) reticulospinal and 4) propriospinal circuits. Our Specific Aims are to determine whether selective expression of DREADDs in (Aim 1) all large diameter (proprioceptive and tactile) neurons and (Aim 2) large proprioceptive afferents only can enhance recovery. The rationale for these aims is that afferent stimulation is hypothesized to work through selective excitation of large diameter sensory afferents (LDSA) that both drive motor pools locally and facilitate proprio- and surpraspinal input. To date, it has not been possible to definitively determine which afferents were recruited after electrical stimulation, or to select between afferents of similar diameter. The significance of this work lies in determining whether recovery is mediated exclusively by proprioceptive axons or a combination of proprioceptive and tactile afferents, and uncovering the mechanisms of functional plasticity in the spinal cord.

项目概要 脊髓损伤（SCI）会导致终生神经功能障碍，目前尚无治疗方法 有效的治疗。该提案的前提是最近的工作表明传入 刺激与跑步机训练相结合可以增强站立、迈步和意志控制 在人类和动物模型中。因此，了解其机制至关重要 通过传入刺激驱动运动改善。可以识别哪些传入的工具 对于增强恢复是必要且充分的，并且可以促进对 有助于神经可塑性，是迫切需要的。我们的长期目标是开发方法 选择性传入调制，并将其应用于剖析潜在机制 从 SCI 中恢复。这笔赠款的目的是确定哪些传入神经组是重要的 恢复以及脊髓回路如何改变以促进恢复。实现选择性调制 传入并启用遗传追踪，我们将使用由以下人员独家激活的设计受体 可以调节特定神经元群兴奋性的设计药物 (DREADD)。到 准确量化改进，我们将使用深度学习来分析大型运动数据 套。我们的初步数据显示 DREADD 在大直径 DRG 中强烈表达 神经元，CNO 激活它们可以兴奋或抑制 H 反射，并且激活 SCI 后跑步机训练期间的兴奋性 DREADD 改善了步态。我们的主要假设 是跑步机训练期间兴奋性 DREADD (hM3Dq) 对大传入神经的激活 会增强恢复，而抑制性 DREADD (hM4Di) 会抑制恢复。四个子 假设将测试恢复是否是通过增加传入投射到 1）运动来介导的 神经元，或 2) 抑制性中间神经元；或通过 3) 网状脊髓和 4) 本体脊髓的发芽 电路。我们的具体目标是确定 DREADD 是否选择性表达（目标 1）所有大直径（本体感受和触觉）神经元和（目标 2）大本体感受 传入只能增强恢复。这些目标的基本原理是传入刺激是 假设通过选择性激发大直径感觉传入 (LDSA) 发挥作用 既可以驱动局部运动池，又可以促进本体和脊髓上的输入。迄今为止，它已经 无法明确确定电刺激后招募了哪些传入神经 刺激，或在相似直径的传入神经之间进行选择。这项工作的意义在于 确定恢复是否完全由本体感觉轴突或 本体感觉和触觉传入的结合，并揭示其机制 脊髓的功能可塑性。