Developmental noise aids robust motor pattern generation and behavior

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Asynchronous insect flight is a prime example for robust motor pattern generation under variable conditions. In Drosophila, the motoneuron activation sequences required for robust yet adjustable wing power production are produced by a small central pattern generating (CPG) network that is comprised of five electrically coupled motoneurons, MN1-5. P6 is motivated by two recent discoveries that raise questions about the development of this system: First, correct CPG output requires balanced synaptic input to MN1-5. We previously showed that correctly balanced excitatory and inhibitory input to a single MN dendrite develops from probabilistic competition, but it remains unknown how the correct synaptic input balance across the MN1-5 ensemble develops. Second, our preliminary data for RobustCircuit show that CPG function requires differential electrical coupling weights between MN1-5 pairs and equally tuned membrane excitabilities of all five MNs, although ion channel expression is considerably variable. How these imprecisions affect robustness of CPG development and function is unknown. Regarding the first open question, we hypothesize that MN1-5 acquire equal proportions of excitatory synaptic input through synaptotropic growth and competition, both of which are based on intrinsically noisy branching and synapse formation. Regarding the second open question, we hypothesize that imprecise ion channel regulation aids the robust tuning of MN excitability. Moreover, in collaboration with P7, we propose that the mature CPG requires firing pattern imprecision to re-establish preferred MN firing sequences upon perturbation. When these studies are concluded, we will have characterized how intrinsically imprecise development and neuronal properties lead to stereotyped circuit output and robust behavior.