SENSORY AND MOTOR INTEGRATION IN THE SPINAL CORD

我们将研究吻侧抓痕、囊状抓痕和屈曲 脊髓完全横断的海龟的反射 在前肢扩大的后面。 这些皮肤反射 显示了后肢运动神经元激活的独特模式， 触觉刺激在特定的感受野。 我们将记录 运动神经元激活模式的准备固定， 神经肌肉阻滞。 脊髓回路在这个准备，在 缺乏运动相关的感觉反馈，选择并产生一个 适当的运动模式为每一个特定的刺激：电路使一个 运动模式决策，然后产生该运动模式。 我们 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，我们将研究一个人的解剖和生理特性。 特定类别的脊髓神经元，具有 下行轴突 我们将使用这些数据来测试特定的假设， 参与选择的脊髓神经元的特征， 产生抓挠反射运动模式。 第二，我们将继续 谷氨酸受体对皮肤细胞的作用的表征 反射 我们将研究非NMDA和NMDA的相对贡献 感受器的每一个组成部分的屈曲反射。 康贝特人将以 每类谷氨酸受体对吻侧抓挠运动的贡献 模式生成 第三，我们将测量谷氨酸的贡献， 受体激活的propriospinal神经元参与 屈曲反射和吻侧抓挠反射。 在每一个特定的目标，我们将获得有关神经元的信息， 脊髓中皮肤感觉运动整合的机制 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起到作用， 脊髓感觉运动整合研究假说 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.