Quantitative Biosciences Thesis Proposal 

Casey King

School of Physics

Advisor: Prof. Simon Sponberg (School of Physics; School of Biological Sciences)

Elucidating Expression of Intrinsic Muscle and Joint Properties During Unsteady Locomotion

Thursday, November 12, 2026, 11:00 AM
Cherry Emerson 320

Teams Link: https://teams.microsoft.com/meet/2352900848183937?p=NBUmIgqTOp7utZfEAV

Committee Members:

Prof. Jennifer Curtis (Georgia Institute of Technology; School of Physics)

Prof. Shiladitya Banerjee (Georgia Institute of Technology; School of Physics)

Prof. Emanuel Azizi (University of California, Irvine; School of Biological Sciences) 

Abstract 

Animals use neuromuscular systems to navigate complex, varied terrains. Muscle offers an incredible variety of control mechanisms that help animals locomote during perturbations and unsteady locomotion: conditions in which muscles undergo rapid changes in strain and force. Intrinsic muscle properties, changing external loads, and antagonistic muscle interactions create a hierarchy of control that extends from individual muscles to antagonistic pairs and ultimately to multi-muscle joint systems. To advance our understanding of muscle function, experimental approaches must extend beyond steady state contractions to conditions that more accurately reflect the mechanical challenges encountered during natural locomotion. Insects provide an ideal model for these investigations because their muscles are controlled by relatively few motor units and exhibit well-characterized activation patterns, enabling precise study of muscle function under both steady-state and perturbed conditions. This thesis investigates how intrinsic muscle properties contribute to locomotor control during unsteady movement. First, we characterize the physiological conditions that enable a single moth flight muscle to produce sufficient power. We then determine the molecular mechanisms underlying the nonlinear force production that emerges during rapid stretch. Unlike moths, cockroaches enable us to investigate how antagonistic limb muscles contribute to successful terrestrial locomotion. During periods of high ground reaction forces, overlapping activation patterns and mechanical coupling within the joint may allow these muscles to modify one another's function. Finally, we determine how these physiological and mechanical interactions influence locomotor performance in behaviorally relevant contexts.