Räumlich-zeitliche Dynamik verteilter Netzwerk-Aktivität als Determinate zielgerichteter Verhaltensabfolgen im Nervensystem des Wirbeltiers

目标导向行为是由几个连续执行的运动步骤组成的，这些步骤可能涉及眼睛、头部和伸展运动。目标导向的行为序列是由外部感觉刺激触发的。序列的后续要素及其成功完成依赖于步骤之间的感觉反馈、运动指令的内部监控以及内部状态变量，如注意力、期望和动机。在多步序列中，中脑顶盖和脑干核团中不同类型的神经元表现出与感觉刺激的特征相关的放电模式，或者与运动模式的规划、选择和执行有关的方面。我们计划研究这些不同的神经元如何控制斑马鱼幼体(Danio Rerio)视觉运动系统中的多步序列这一悬而未决的问题。由于其体积小、皮肤透明和遗传延展性，这个脊椎动物模型提供了独特的机会来成像与完整动物的目标导向视觉引导行为相关的分布式网络的神经动力学。具体地说，我们计划测试多步行为序列是否由一组离散的运动模式组成。我们还将测试在视顶盖和网状脊髓系统中是否存在特定的活动时空分布，这些系统编码多步骤序列中的各个步骤。最后，我们将解决神经活动的动力学和短期可塑性如何影响单个运动步骤之间的耦合作为多步骤行为序列效率的决定因素的问题。

Goal-directed behaviors are composed of several sequentially executed motor steps, which may involve eye, head and reaching movements. A goal-directed behavioral sequence is triggered by external sensory stimuli. Subsequent elements of the sequence, and its successful completion, depend on sensory feedback between steps, on the internal monitoring of motor commands, and on internal state variables such as attention, expectation and motivation. During multi-step sequences, different types of neurons in the midbrain tectum and in brain stem nuclei exhibit firing patterns that correlate with features of the sensory stimulus, or with aspects involved in planning, selection and execution of the motor pattern. We plan to investigate the unsolved question of how these different neuronal ensembles control multi-step sequences in the visuo-motor system of the larval zebrafish (Danio rerio). Owing to its small size, transparent skin and genetic malleability, this vertebrate model offers unique opportunities to image the neural dynamics of distributed networks in relation to goal-directed visually guided behaviors in the intact animal. Specifically, we plan to test whether multi-step behavioral sequences are composed of a discrete set of motor patterns. We will also test whether specific spatio-temporal distributions of activity exist in the optic tectum and reticulo-spinal system that encode individual steps of a multi-step sequence. Finally, we will address the question how the dynamics of neural activity and short-term plasticity affect the coupling between individual motor steps as a determinant of the efficiency of a multi-step behavioral sequence.