SENSORY AND MOTOR INTEGRATION IN THE SPINAL CORD

描述（由申请人提供）：脊髓中的神经元网络，称为中枢模式发生器（CPG），具有相当大的运动能力，并且可以在脊髓完全横断的脊椎动物中通过皮肤刺激激活。CPG在用神经肌肉阻滞固定的脊椎动物模型系统中产生协调的运动输出。固定的脊椎龟产生的运动模式的混合协同喙抓，常规协同口袋抓，和常规协同屈曲反射。在吻侧搔抓中，单关节膝伸肌在髋屈肌活动期间活跃;在袋状搔抓中，单关节膝伸肌在髋伸肌活动期间活跃;在屈曲反射中，膝屈肌在髋屈肌活动期间活跃。在这些运动模式中，我们记录了单个单位的下行固有脊髓中间神经元活动。我们测试了Grillner对CPG组织的单位突发发生器假设的预测，其中每个自由度的每个方向都由特定模块控制，例如，髋屈肌，髋伸肌，膝屈肌，膝伸肌，等。我们研究interneurons，是候选成员的每个模块在正常的喙划痕与激动剂和拮抗剂运动输出之间的节奏交替在每个自由度;拮抗剂活动发生在激动剂静止。我们测试预测的interneuronal活动或静止在3个电机模式的变化，喙划痕，称为删除。在拮抗剂缺失期间，在连续激动剂爆发之间没有静止，并且没有拮抗剂运动活性。我们研究髋关节相关和膝关节相关的缺失。我们测试预测的神经元间的相位恒定性或转移时，口袋划痕比较与喙划痕和预测的神经元间的激活或静止在屈曲反射。我们的实验揭示了海龟CPGs的关键特征。包括人类在内的所有脊椎动物的脊髓组织都有相当大的相似性。我们对CPG组织的研究结果将对那些为脊髓损伤的人开发新疗法的人感兴趣。

DESCRIPTION (provided by applicant): Neuronal networks in the spinal cord, termed central pattern generators (CPGs), have considerable motor capacity and can be activated by cutaneous stimulation in a spinal vertebrate with complete spinal cord transection. CPGs produce coordinated motor output in model systems of spinal vertebrates immobilized with neuromuscular blockade. The immobilized spinal turtle produces the motor patterns of mixed-synergy rostral scratch, conventional-synergy pocket scratch, and conventional-synergy flexion reflex. In rostral scratch, monoarticular knee extensors are active during hip-flexor activity; in pocket scratch, monoarticuiar knee extensors are active during hip-extensor activity; in flexion reflex, knee flexors are active during hip-flexor activity. We record single-unit descending propriospinal interneuron activity during these moter patterns. We test predictions of Grillner's unit-burst-generator hypothesis of CPG organization in which each direction of each degree of freedom is controlled by a specific module, e.g., hip flexor, hip extensor, knee flexor, knee extensor, etc. We study interneurons that are candidate members of each module during normal rostral scratch with rhythmic alternation between agonist and antagonist motor output at each degree of freedom; antagonist activity occurs during agonist quiescence. We test predictions of interneuronal activity or quiescence during 3 motor-pattern variations of rostral scratch, termed deletions. During an antagonist deletion, there is no quiescence between successive agonist bursts and no antagonist motor activity. We study hip-related and knee-related deletions. We test predictions of interneuronal phase constancy or shifting when pocket scratch is compared with rostral scratch and predictions of interneuroral activation or quiescence during flexion reflex. Our experiments reveal critical characteristics of turtle CPGs. There is considerable similarity in the organization of spinal cord in all vertebrates, including humans. Our findings of CPG organization will be of interest to those developing new therapies for spinal-injured humans.