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: 10468315
• 负责人: Andrew Spence
• 金额: $ 39.2万
• 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/10468315
• 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; Recovery Support; 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.

项目摘要 脊髓损伤（SCI）导致终身神经功能障碍，目前没有 有效治疗。这个建议的前提是最近的工作表明，传入 刺激与跑步机训练配对可以增强站立，踏步和意志控制 在人类和动物模型中。因此，了解这些机制至关重要 传入刺激通过其驱动运动改善。可以识别哪些传入的工具 是必要和充分的，以提高回收率，这可以促进表征的 有帮助的神经可塑性，是迫切需要的。我们的长期目标是制定方法， 选择性传入调制，并将其应用于解剖的机制， 从SCI中恢复。这项资助的目的是确定哪些传入神经是重要的 以及脊髓回路如何改变以促进恢复。为了实现选择性调节， 传入并启用遗传跟踪，我们将使用设计器受体， 设计药物（DREADD）可以调节特定神经元群体的兴奋性。到 准确量化改进，我们将使用深度学习来分析大型运动学数据 集.我们的初步数据显示DREADDs在大直径DRG中的强表达 神经元，它们的激活CNO可以激发或抑制H-反射，和激活 SCI后跑步机训练期间的兴奋性DREADDs改善了步进。我们的主要假设是 是在跑步机训练期间由兴奋性DREADD（hM 3Dq）激活大传入 将增强恢复，而抑制性DREADD（hM 4Di）将抑制恢复。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 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.我们的具体目的是确定DREADD在（Aim）中的选择性表达是否 1)所有大直径（本体感受和触觉）神经元和（Aim 2）大本体感受 传入只会促进恢复。这些目标的基本原理是传入刺激是 假设通过大直径感觉传入（LDSA）的选择性兴奋工作 既能驱动局部运动池，又能促进脊柱内和脊柱外输入。迄今为止， 无法确定哪些传入神经在电刺激后被招募 刺激，或选择类似直径的传入。这项工作的意义在于 在确定恢复是否仅由本体感受轴突介导或 本体感受和触觉传入的结合，并揭示了 脊髓的功能可塑性