Theses and Dissertations at Montana State University (MSU)
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Item Small scale stimuli and the cricket cercal system(Montana State University - Bozeman, College of Agriculture, 2022) Mulder-Rosi, Jonas L.; Co-chairs, Graduate Committee: Charles M. Gray and R. Steven Stowers; This is a manuscript style paper that includes co-authored chapters.The cricket cercal system has been a model system in neuroscience for over 30 years. Anatomy, physiology, and theory have all come together to produce a picture of a system with a clear purpose: encoding air direction around the animal. However, certain features of the system have suggested that these cells may be sensitive to additional stimulus dimensions. To address this limited stimulus space I designed new experiments to test these neurons' responses to previously untested stimuli. I used a novel extracellular recording mechanism able to record and sort several neurons' responses at the same time. I built and tested several stimulators to provide small-scale puffs to specific parts of the sensory array at specific times. With these, I was able to test this model neural system against a complex stimulus space. I show here that these neurons respond to several additional stimulus dimensions. They are tuned to the timing of stimuli across the array. They show differential responses to even more complex stimuli with varying stimulus directions in different locations across the array. This implies that the previous understanding of the system was likely limited by how it was tested. While these cells accurately encode the direction of large-scale airflow, they also encode other aspects of stimuli, such stimulus timing and small-scale variations in stimulus direction. Thus the "function" of these neurons may be far more complex than previously understood.Item A study of the hydrocarbons of the cuticular wax of Anabrus simplex Hald(Montana State University - Bozeman, College of Letters & Science, 1962) Leibrand, Roger JohnItem The free fatty acids and neutral lipids of the cuticular wax of the Mormon cricket, Anabrus simplex, Hald(Montana State University - Bozeman, College of Letters & Science, 1964) Padmore, Joel MackieItem Composition of the cuticular wax of Anabrus simplex Hald(Montana State University - Bozeman, College of Letters & Science, 1959) Baker, Graeme LevoItem Biomechanical analysis of a cricket filiform hair socket under low velocity air currents(Montana State University - Bozeman, College of Engineering, 2012) Joshi, Kanishka Bhuwanchandra; Chairperson, Graduate Committee: Ahsan MianFiliform hairs of crickets are of great interest to engineers because of the hairs' highly sensitive response to low velocity air currents. In this study, the cercal sensory system of a common house cricket is analyzed. The sensory system consists of two antennae like appendages called cerci that are situated at the rear of the cricket's abdomen. Each cercus is covered with 500-750 flow sensitive hairs that are embedded in a complex viscoelastic socket that acts as a spring and dashpot system and guides the movement of the hair. When a hair deflects due to the drag force induced on its length by a moving air-current, the spiking activity of the neuron that innervates the hair changes and the combined spiking activity of all hairs is extracted by the cercal sensory system. The hair has been experimentally studied by researchers though its characteristics are not fully understood. The socket structure has not been analyzed experimentally or theoretically from a mechanical standpoint, and the characterization that exists is mathematical in nature and only provides a very rudimentary approximation of the socket's spring nature. This study aims to understand and physically characterize the socket's behavior and interaction with the filiform hair by presenting and proving new hypotheses about the hair and socket behavior. The operating principles of the socket can be used for the design of highly responsive MEMS devices such as fluid flow sensors or micromanipulators. A three dimensional computer aided design (CAD) model was first created using confocal microscopy images of the hair and socket structure of the cricket, and then finite element analyses based on the physical conditions the insect experiences were simulated. The results show that the socket acts like a spring but due to its constitutive non-standard geometric shapes, it deforms like a thin membrane at times or like a plate in bending at other instances. It was also determined that the socket provides far greater resistance to hair movement than what has been previously postulated and computed by researchers.Item Using the penalty immersed boundary method to model the interaction between filiform hairs of crickets(Montana State University - Bozeman, College of Engineering, 2011) Gordon, Eric Duane; Chairperson, Graduate Committee: Jeffrey HeysFluid-structure interactions are important in a wide range of applications and, due to their complexity, need extensive experimental and computational research. One such example comes from crickets, which have evolutionarily developed an excellent micro-air-flow sensory system. Understanding principles of the cricket' micro-air-flow sensor will help design and manufacture artificial sensors. This thesis focuses on improving and validating a Penalty Immersed Boundary (PIB) model of the cricket sensory system, which consists of hundreds of filiform hairs. Previous efforts by others have modeled the filiform hair as a rigid inverted pendulum. Advantages to the PIB approach over previous models include a flexible fluid solver (previous models used an idealized, analytical flow field), the filiform hairs are not required to be completely rigid, and, most importantly, the entire cerci and all the filiform hairs can be modeled. The first goal was to improve the precision and accuracy of modeling a single filiform hair by adjusting model parameters so that the model predictions more accurately fit experimental data. A second goal was to model a portion of a full cercus based on filiform hair data from a real cricket and use the model to determine the interactions occurring between multiple hairs and identify any evolutionary optimization of the cercal system.Item Determining the biomechanical response of a filiform hair array : a low Reynolds number fluid-structure model(Montana State University - Bozeman, College of Letters & Science, 2009) Cummins, Breschine; Chairperson, Graduate Committee: Tomas GedeonA model system that has been the subject of many anatomical, developmental, functional, and theoretical studies over the last 30 years is the cercal sensory system of the cricket. This system is composed of two antenna-like appendages covered with hundreds of filiform mechanosensory hairs, and encodes information about the direction and dynamics of low-velocity air currents. The encoding is determined by the biomechanical properties of the mechanosensory hairs. These properties are poorly understood, primarily because accurate experimental measurements of the air-current-driven movements of the hairs are difficult to obtain, and adequate mathematical tools for modeling arbitrarily complex hair-to-hair interactions within the canopy have been absent. The study presented here solves fundamental problems in both of these areas. Previous studies have characterized the biomechanics of the filiform hairs, but only one study considered the fluid-mediated interaction of closely-packed hairs. A major goal of our work was to model the motion of a dense patch of thin filaments driven by bulk fluid flow, in a context that is immediately relevant to the cercal system. To understand the function of the sensory epithelium as a whole, we developed a numerical model based on a novel mathematical tool: the method of regularized unsteady Stokeslets. This method is generally applicable to low Reynolds number fluid flow in domains that are subject to periodic forcing along the boundary. The numerical scheme associated with our mathematical model is fast, scalable, accounts for the interaction between arbitrary arrangements of hairs. We measured the biomechanical stimulus-response properties of 19 filiform hairs, and used that data to fit parameters to our mathematical model. We demonstrate for the first time that one of the mechanical parameters controlling filiform hair motion depends on the frequency of the air stimulus. Our numerical simulations demonstrate that damped and synergistic hair interactions can occur between closely-packed hairs. Low frequency signals (< 50 Hz) are damped, and higher frequency signals (50-200 Hz) are amplified. We hypothesize that the characteristic dense patch of hairs at the proximal end of the cercus acts as a noise cancellation filter that removes low frequency components of ambient environmental stimuli.