Mechanisms Mediating Motor Pattern Selection from a Multi-Functional Neuronal Network

IBN-9808356 Nusbaum Lay摘要这项建议的目标是在细胞水平上理解如何从多功能神经元网络中选择特定的节律运动模式。之前在几个无脊椎动物和脊椎动物系统中的研究表明，产生有节奏运动的网络在功能上是灵活的。也就是说，当不同的神经调节输入影响时，相同的神经元集合产生不同的有节奏的运动模式。我们不完全理解如何从这样的网络中选择任何单独的运动模式来激活。然而，运动模式的选择可能涉及来自高级中枢的不同输入的共同激活。这一点和有关运动模式选择的相关问题很容易在口胃神经系统中得到解决。这是一个特征非常明确的模型系统，它包含一组截然不同但相互作用的网络，这些网络产生参与食物摄取、咀嚼和加工的前肠横纹肌肉有节奏收缩的运动模式。就像所有节律活跃的网络一样，这些网络仍然可以在完全隔离的神经系统中运行，所有的实验都将在那里进行。工作假设是，从多功能神经元网络中选择运动模式的部分原因是不同的输入路径(即不同的感觉系统)，对调制投射神经元的重叠亚群有不同的影响。为了检验这一假说的有效性，我们建议检验是否：(1)不同的输入路径从同一网络中唤起不同的运动模式；(2)这些不同的输入路径激活影响该网络的不同投射神经元子集；(3)由已识别的感觉神经元释放的不同的共同递质被用来影响空间上分离的神经元目标；以及(4)单个感觉路径表现出活动依赖的行为区隔。结合电生理学、药理学和解剖学的方法将达到这些目的。这项拟议的研究将为神经系统如何从多功能神经网络中选择不同的运动模式提供新的生理学信息。对于在数值上更复杂的脊椎动物神经系统中发生的可比较但更难获得的事件，这将是一个有价值的模型。它还将为对中枢神经系统功能组织感兴趣的博士后和博士后学生提供广泛的技术和智力培训。

IBN-9808356 Nusbaum LAY ABSTRACT The goal of this proposal is to understand, at the cellular level, how specific rhythmic motor patterns are selected from a multifunctional neuronal network. Previous work in several invertebrate and vertebrate systems has shown that the networks generating rhythmic movements are functionally flexible. That is, the same neuronal ensemble generates distinct rhythmic motor patterns when influenced by different neuromodulatory inputs. We do not fully understand how any individual motor pattern is selected for activation from such a network. Motor pattern selection, however, is likely involve the coactivation of distinct inputs from higher centers. This and related issues regarding motor pattern selection are readily addressed in the stomatogastric nervous system. This is a very well-characterized model system that contains a set of distinct but interacting networks that generate the motor patterns underlying rhythmic contractions of striated foregut muscles involved in the ingestion, chewing and processing of food. As is true for all rhythmically active networks, these networks can still operate in the completely isolated nervous system, where all experiments will be performed. The working hypothesis is that motor pattern selection from a multifunctional neuronal network results in part from different input pathways (i.e.- different sensory systems) having distinct effects on overlapping subsets of modulatory projection neurons. To examine the validity of this hypothesis, we proposed to examine whether: (1) different input pathways evoke different motor patterns from the same network; (2) these different input pathways activate different subsets of projection neurons that influence this network; (3) different co-transmitters released by an identified sensory neuron are used to influence spatially separate neuronal targets, and (4) an individual sensory pathway exhibits an activity- dependent compartmentalization of action. Combining electrophysiological, pharmacological and anatomical approaches will attain these aims. This proposed study will provide novel physiological information regarding how the nervous system selects different motor patterns from a multifunctional neuronal network. This will be a valuable model for comparable but less accessible events occurring in the numerically more complex vertebrate nervous system. It will also provide extensive technical and intellectual training for pre- and post- doctoral students interested in the functional organization of the central nervous system.