Generation of Metachronal Motor Patterns in Segmented Nervous Systems

分段神经系统中异时运动模式的生成

• 批准号: 0091284
• 负责人: Brian Mulloney
• 金额: $ 30万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-08-01 至 2005-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0091284&HistoricalAwards=false
• 关键词: Generation; Metachronal; Motor; Patterns; Segmented

Locomotion in vertebrates and arthropods is a complex behavior, and the neural mechanisms that coordinate their limbs during locomotion are not well understood. The abdominal swimmeret system of the crayfish provides a relatively simple and accessible system to study the intersegmental coordination of movement. Within each segment of the tail, the swimmeret paddles show an alternating power stroke and a return stroke, as in most locomotor appendages, and the strokes of adjacent segments show specific timing relationships. There are small circuits of neurons (nerve cells) within each segment that have known identifiable single cells driving particular motor movements, and three types of interneurons that are involved in coordinating the movements. It is particularly useful that the crayfish ventral nerve cord and swimmeret system can be isolated in vitro and still show the intersegmentally coordinated swimming pattern. This project uses a combined physiological and computational modeling approach to define the dynamic circuitry for the pattern. A cellular model of the nerve cell physiological properties and network connections is used to predict the phase patterns of bursts of nerve impulse activity of the relevant neurons in the system. These predictions are compared with the activity patterns and connectivity in individual neurons recorded physiologically in the living circuit, including the small electrical potentials at synaptic connections between pairs of single neurons as well as the impulse traffic between segments. The relative importance of local and intersegmental pathways are assessed by stimulating individual coordinating interneurons when the intersegmental pathways are intact and when they are blocked. Intracellular dye fills anatomically confirm physiological connecting pathways. Refinements of the model by the experimental findings will yield a thorough description of how the dynamics of the interneurons contribute to stable intersegmental coordination, and how the properties of the synapses contribute to normal locomotion. This work will have an impact beyond crustacean locomotion research, by leading to new insights about neural mechanisms that underlie the much more complex vertebrate circuits for locomotion. The integration of computational modeling with physiology will also have an impact on needed multi-disciplinary training of students and postdoctoral researchers in neuroscience and physiology in general.

脊椎动物和节肢动物的运动是一种复杂的行为，运动过程中协调四肢的神经机制尚不清楚。 小龙虾的腹部游泳足系统为研究运动的节间协调提供了一个相对简单且易于使用的系统。 在尾巴的每个节段内，游泳足的桨显示出交替的动力冲程和返回冲程，就像大多数运动附肢一样，并且相邻节段的冲程显示出特定的时序关系。 每个节段内都有神经元（神经细胞）的小回路，这些回路具有已知可识别的驱动特定运动运动的单细胞，以及参与协调运动的三种类型的中间神经元。 特别有用的是，小龙虾腹神经索和游泳足系统可以在体外分离，并且仍然显示出节间协调的游泳模式。 该项目使用结合的生理和计算建模方法来定义模式的动态电路。 神经细胞生理特性和网络连接的细胞模型用于预测系统中相关神经元的神经冲动活动爆发的相位模式。 这些预测与活体回路中生理记录的单个神经元的活动模式和连接性进行比较，包括单个神经元对之间突触连接处的小电位以及片段之间的脉冲流量。 当节间通路完整和被阻断时，通过刺激个体协调中间神经元来评估局部和节间通路的相对重要性。 细胞内染料填充在解剖学上确认了生理连接通路。 通过实验结果对模型进行改进，将全面描述中间神经元的动力学如何有助于稳定的节间协调，以及突触的特性如何有助于正常的运动。 这项工作将产生超越甲壳类运动研究的影响，通过带来关于更复杂的脊椎动物运动回路基础的神经机制的新见解。 计算模型与生理学的整合也将对神经科学和生理学领域的学生和博士后研究人员所需的多学科培训产生影响。