Meeting Abstract
Control of undulatory swimming is due to the interplay of central and peripheral mechanisms. It has been observed that centrally distributed neural networks along the spinal cord, so-called central pattern generators (CPGs), contribute to spontaneous rhythm generation in a variety of animal species (e.g. lampreys, leeches or salamanders). On the other hand, local feedback loops exist that are able to modulate and alter the activation patterns along the body. However, much less is known about these feedback mechanisms and because it has proved difficult to analyze their contribution isolated from the central nervous system, corresponding models have become valuable tools for investigations. Some models have described CPGs together with local proprioceptive feedback loops involving stretch receptors and attempted to quantify their respective contributions. In our recent study we present a new model that incorporates exteroceptive sensing by means of local pressure/force measurements. The model is based on phase oscillators with local force feedback and simple muscle models. We used both simulation and a robot to test our model and made two major findings. (1) Travelling waves of undulation can emerge spontaneously in the absence of any central coupling along the body and feedback loops can take over the role of synchronizing the oscillatory centers. (2) In the absence of CPGs, (centrally coupled) purely sensory-driven oscillations can generate coherent traveling waves along the body. Our results highlight the importance of body-environment interaction for pattern generation in undulatory swimming and suggest that incorporation of local force and/or pressure sensing and feedback provides redundancy and robustness for undulatory swimming control.
