Quantitative Biosciences Thesis Proposal
Malaika Taylor
School of Biological Sciences
Advisor: Prof. Simon Sponberg (School of Physics; School of Biological Sciences)
Mechanosensory Mediated Coordination in Invertebrates During Environmental Interactions
Monday, November 16, 2026, 3:00PM
Howey W401
Committee Members:
Prof. Kelimar Diaz (Oglethorpe University; Division of Natural Sciences - Physics)
Prof. Daniel Goldman (Georgia Institute of Technology; School of Physics)
Prof. Matthew McHenry (University of California, Irvine; School of Biological Sciences)
Abstract
In complex environments, animals use mechanosensory interactions with objects around them for exploration and adaptive locomotion. These interactions provide afferent signals to feedback loops that inform their behavior and coordination. These afferent signals provide information from sensory organs that detect forces like load, strain, and substrate contact. When walking, the load experienced by the legs changes with the terrain and phase of the gait cycle. These changes in experienced load directly affect inter- and intra-limb coordination. When the distribution of the weight on the legs changes or is removed, we see changes in muscle activation, gait, and phasing of locomotor cycle. Animals leverage the intrinsic properties of their muscles (e.g history dependence) and adjust their control strategies (e.g. antagonistic co-activation, spike timing) to maintain stable locomotion in these different limb loading conditions. We will use the discoid cockroach, Blaberus discoidalis, to better understand the context-dependence and usage of these muscle properties and control strategies. B. discoidalis allows for us to collect discrete spikes from the motor neurons, due to their small motor unit to muscle ratio and easy to access neuromuscular structures. First, we will define the role of antagonistic co-activation on limbs without vertical load. Antagonistic co-activation happens when muscles that produce opposing forces around the same joint are active at the same time. It is seen as a way to accommodate for load by modulating joint stiffness. Secondly, we will identify the modulation of antagonistic co-activation and co-contraction across limbs during abrupt and sustained changes in load distribution. By measuring muscle activity of the middle and hind limbs on flat ground, slopes, and the transition between them, we can better understand how co-activity is modulated across limbs. Next, we will determine the history-dependent functional changes in antagonistic muscles during abrupt load changes. History dependence is the effect that the current state of the muscle has on force production. Measuring how co-contracted muscle contributes to force production during load changes across different phases of the locomotor cycle will help us understand how the intrinsic properties of muscle adapt force output in response to perturbations. Finally, we will explore a mechanosensory-mediated behavior that involves the processing of horizontal forces through antenna, called wall-following. This behavior has previously been studied in cockroaches, which are compact hexapods with hydraulically controlled antennae. We will be using Scolopendra subspinipes, an elongated undulating myriapod with muscle-actuated antenna, to understand how this evolutionarily conserved behavior changes with drastic changes in antennal and body morphology. We will investigate how coordination of their body changes with wall-following. Together, these aims will expand our understanding of how mechanosensory-mediated behavior and neuromuscular control and coordination changes with morphology, intrinsic muscle properties, and environmental contexts.