SENSORY AND MOTOR INTEGRATION IN THE SPINAL CORD

我们将学习肩部划痕、口袋划痕和屈曲。 完全横断脊髓的海龟的反射 在前肢扩大之后。每一种皮肤反射 在反应中显示出明显的后肢运动神经元激活模式 触觉刺激在特定的感受场内。我们将录制 固定化制剂中运动神经元的激活模式 神经肌肉阻滞。在这个准备中的脊髓回路，在 缺乏与运动相关的感觉反馈，选择并产生 适合每个特定刺激的运动模式：该电路使 马达模式决定，然后产生那个马达模式。我们的 实验将揭示脊髓神经元机制负责 这些过程。 我们将使用几种实验策略来研究这些机制。 首先，我们将研究一个解剖和生理特性 特定类型的脊髓神经元，这组固有脊髓神经元 下降的轴突。我们将使用这些数据来检验关于以下方面的具体假设 脊髓神经元参与选择和选择的特征 抓挠反射运动模式的生成。第二，我们将继续 谷氨酸受体对皮肤的作用 条件反射。我们将考察非NMDA和NMDA的相对贡献 屈曲反射各部分的感受器。我们将确定 各类谷氨酸受体在嘴部抓挠运动中的作用 图案生成。第三，我们将测量谷氨酸的贡献 激活固有脊髓神经元的受体参与 屈曲反射和在吻部的抓挠反射。 在每个特定的目标中，我们将获得关于神经元的信息 脊髓内皮肤感觉运动整合的机制 电源线。海龟的脊髓与其他脊椎动物的脊髓相似， 包括人类。我们将揭示的机制可能会发挥作用 其他研究脊髓感觉运动整合的假说 脊椎动物。

We will study the rostral scratch, the pocket scratch, and the flexion reflex in the turtle with a complete transection of the spinal cord just posterior to the forelimb enlargement. Each of these cutaneous reflexes displays a distinct pattern of hindlimb motor neuron activation in response to tactile stimulation within a specific receptive field. We will record motor neuron activation patterns in a preparation immobilized by neuromuscular blockade. Spinal cord circuitry in this preparation, in the absence of movement-related sensory feedback, selects and generates an appropriate motor pattern for each specific stimulus: the circuitry makes a motor pattern decision and then produces that motor pattern. Our experiments will reveal spinal cord neuronal mechanism responsible for these processes. We will use several experimental strategies to study these mechanisms. First, we will study the anatomical and physiological properties of a specific class of spinal cord neuron, the set of propriospinal neurons with descending axons. We will use these data to test specific hypotheses about the characteristics of spinal neurons involved in the selection and generation of scratch reflex motor patterns. Second, we will continue our characterization of the contributions of glutamate receptors to cutaneous reflexes. We will examine the relative contributions of non-NMDA and NMDA receptors to each component of the flexion reflex. We will determine the contribution of each class of glutamate receptors to rostral scratch motor pattern generation. Third, we will measure the contribution of glutamate receptors to the activation of propriospinal neurons involved in the flexion reflex and in the rostral scratch reflex. In each specific aim, we will obtain information concerning the neuronal mechanisms responsible for cutaneous sensorimotor integration in the spinal cord. Turtle spinal cord is similar to that of other vertebrates, including humans. The mechanisms we will reveal may serve as working hypotheses for studies of spinal cord sensorimotor integration in other vertebrates.