SENSORY AND MOTOR INTEGRATION IN THE SPINAL CORD

描述(申请人提供)：脊髓中的神经元网络，称为中央模式发生器(CPGs)，具有相当大的运动能力，可以通过皮肤刺激在脊髓完全横断的脊椎动物中激活。CPGS在用神经肌肉阻滞剂固定的脊椎动物模型系统中产生协调的运动输出。固定的脊甲鱼产生混合协同嘴部抓挠、传统协同口袋抓挠和传统协同屈曲反射的运动模式。在肩部划痕中，单关节膝关节伸肌在髋屈肌活动中处于活跃状态；在口袋划痕中，单关节膝关节伸肌在髋关节伸展活动中处于活跃状态；在屈曲反射中，膝关节屈肌在髋屈肌活动中处于活跃状态。我们记录了在这些运动模式中，单个单位下降的固有脊髓中间神经元的活动。我们检验了Grillner关于CPG组织的单位突发产生器假说的预测，在该假说中，每个自由度的每个方向都由特定的模块控制，例如髋屈肌、髋伸肌、膝关节屈肌、膝关节伸肌等。我们研究了在正常的吻部抓挠过程中，作为每个模块候选成员的中间神经元，在每个自由度上激动剂和拮抗剂运动输出之间的节律性交替；拮抗剂活动发生在激动剂静止期间。我们测试了在吻部划痕的3种运动模式变化中对神经元间活动或静止的预测，称为缺失。在拮抗剂删除期间，在连续的激动剂爆发和没有拮抗剂运动活动之间不存在静止。我们研究与髋关节和膝盖相关的缺失。我们测试了当口袋划痕与吻部划痕相比较时神经元间相恒定或移位的预测，以及在屈曲反射中神经元间激活或静止的预测。我们的实验揭示了海龟CPG的关键特征。包括人类在内的所有脊椎动物在脊髓的组织结构上都有相当大的相似性。我们对CPG组织的发现将对那些为脊柱损伤人类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.