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

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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.