Neuromechanical Resonance and Distributed Control in Organismal Pumping

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For many swimming and flying animals, locomotion emerges from the transfer of momentum from an organism's body or appendage to the local fluid environment. This motion is a result of internal neuromechanical processes that translate neural signals into the activation of muscular tissue. As tissue-engineered pumps and biohybrid robotics improve with every technological advancement, developing the theory behind the actuation of their excitable materials is paramount. While much of the theory in organismal biomechanics and biomimetic materials has examined their performance in the context of mechanical resonance, very little work has been done examining the internal actuation of excitable materials. The interplay between neural time scales, that signal for muscular activation, and mechanical time scales, that are inherent to the elastic profile of the structure, have been found to play an important role in the resulting motion of an actuated material. Furthermore, understanding the role pacemakers play in driving the neural signaling can elucidate how robustness can be ingrained into excitable systems. This research program will develop and employ a suite of mathematical models that describe neuromechanical activation and pacemaker processes, as well as incorporate “living” materials into computational fluid-structure interaction models. The mathematical principles developed here are relevant in the design of actuators for other biological pumps and systems with excitable materials. The project will involve work with both graduate and undergraduate students. The focus of this research program will be to both examine the mathematical theory that girds the interplay between the neuromechanical actuation wave speed and the material wave speed, as well as examine the role pacemaker processes play in driving these neuromechanical systems. To examine this interplay, a moon jellyfish is chosen as a model organism due to the relative simplicity of their nervous system and muscle morphology. To develop this framework the investigators will employ three different classes of mathematical models: (1) 1-D/2-D elastic wave equation model with internal actuation; (2) a coupled neuronal network model to describe the neurophysiological activity that leads to actuation; (3) a 3-D computational fluid-structure interaction (FSI) model to describe the forces and motion of a jellyfish bell. The research program's focus is on the roles of actuation wave speeds, pacemaker processes, and the fluid environment plays in the performance of organismal pumps and excitable materials. The resulting framework will be used to develop the first 3-D model of a swimming organism that fully couples the surrounding fluid with an animal whose emergent kinematics are a consequence of neuromuscular activation, elastic properties, and pacemaker processes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.