Meeting Abstract
53.3 Thursday, Jan. 6 Reflexes and running: Modeling neural feedback in a running cockroach PROCTOR, Joshua/L*; HOLMES, Philip; Princeton University jproctor@princeton.edu
We have developed an integrated model for insect locomotion that includes a central pattern generator (CPG), nonlinear muscles, hexapedal geometry and a representative proprioceptive sensory pathway. In previous work, we have investigated the role of proprioceptive feedback in a single-degree-of-freedom limb controlled by a neural and muscular system. The implemented neural feedback, representative of actual sensory feedback systems in insects (1), was shown to counter perturbations and capture the behavior of sensory systems in the cockroach. We have extended this work to body with a hexapedal geometry running in the plane. This model helps us focus on the central point of this research: how neural feedback enhances the stability already provided by preflexive mechanisms, such as the nonlinear muscle properties and body mechanics (2). With neural feedback modulating the timing of muscle activity via the motoneurons, the hexapedal model can more effectively counter impulsive perturbations. Due to the complexity of the hexapedal model, arising from the large number of neurons, muscles, and etc., the model is easy to simulate but difficult to analyze. We employ phase reduction and averaging theory to reduce the complexity. Importantly, the reduced model captures the dynamics of unperturbed gaits and counters impulsive perturbations similar to the original model. Also, the reduced model allows for a better understanding of reflexive feedback mechanisms as well as providing a platform for studying different aspects of cockroach locomotion such as performing a turning maneuver, recovering from different types of perturbations, and integrating different reflexive pathways currently being experimentally validated. (1) S.N. Zill, A.L. Ridgel, R.A. DiCaprio, and S.F. Frazier. (2) P. Holmes, R.J. Full, D. Koditschek, and J. Guckenheimer.
