CRCNS US-German Research Proposal: Central Pattern Generators and Reflexive Feedback in Insect Locomotion: A Cross-Species Study

Princeton University, Princeton NJ

Investigators

Abstract

Animal locomotion begins in the central nervous system and results in quantifiable mechanical activity; it therefore provides an excellent window into the neural computations that create intentional behaviors and respond to environmental conditions. Locomotion originates in central pattern generators: neural networks in the spines of vertebrates and thoracic ganglia of insects that produce rhythmic movements. Some preparations (e.g. lamprey, crayfish) can produce stable, near-periodic rhythms in isolation, others either require sensory feedback to produce functional gaits or are significantly stabilized by it. Cockroaches and stick insects exemplify these two extremes. They share the same basic neural and biomechanical architecture, but the former run rapidly over rough ground, while the latter are adapted for slow walking on twigs and leaves with varied orientations to gravity. Using existing information and collecting new data, this project will compare these species and address questions such as: (1) What is the functional organization of feedforward motor coordination: How are neural circuits that drive individual legs and joints coupled to achieve inter-limb coordination? (2) What is the role of sensory input in coordination: How does feedback affect motor patterns, and how does locomotion modulate incoming sensory information? (3) How are pattern generators and sensory feedback systems modulated to create appropriate actions as animals change speed, face unexpected perturbations, and maneuver to negotiate complex terrain? The development of integrated mathematical and computational models is central to answering such questions. New data will improve existing models, and new models will be created to span the morphological and behavioral ranges from stick insects to cockroaches, allowing us to illuminate their adaptive strategies to different environments. This research will deepen our understanding of the generation and control of locomotion, with general relevance to animals and humans. The US component of this project is jointly funded by the Mathematical Biology program in the Division of Mathematical Sciences and the Neural Systems Cluster in the Division of Integrative Organismal Systems. The German component is funded by the German Ministry of Education and Research (BMBF).