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Title: Experimental and theoretical investigations into the active nonlinear processes of mosquito audition
Author: Jackson, Joseph C.
ISNI:       0000 0004 2708 4566
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2012
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Audition is a fundamental tool for biological organisms to detect sound. Sensing the weakest sounds requires metabolically active processes that enhance the nanometre-size oscillations of sound sensors. Mosquitoes are a model system for active audition, incorporating many of the properties found in vertebrate active mechanics. In the mosquito, plumose antennae are used as oscillators that are driven by the flow of particles caused by sound. These antennae are adapted to be resonantly tuned to the female sound, such that they respond maximally to the female wingbeat. As well as their excellent sensitivity, mosquito antennae behave nonlinearly, changing the bandwidth of the oscillator in response to sound intensity. Here they are shown, using Laser Doppler vibrometry, to exhibit hitherto unseen nonlinear features in the antenna, and indeed in audition in general. Amplification and hysteresis of the antennal oscillator occur when presented with a single-frequency stimulus. This nonlinear behaviour is shown to occur when the neuronal sensory ensemble entrains to the sound stimulus. The synchronized neurones can then generate coherent force at the stimulus frequency to modify the parameters of the antennal oscillator, namely natural frequency and dissipation. The mechanism is proposed to be derived from twice-frequency forcing of mechanosensory neurones, evidenced by electrophysiological signalling at twice the stimulus frequency which, when modelled, reproduces remarkably well the experimental response. Such a phenomenon is predicted to harbour the potential for pattern formation in the activity of neurones, a property that would be unparalleled in peripheral auditory organs. This work has therefore revealed the remarkable evolution of both a sensitive and functional sound receiver that relies on the collective behaviour of thousands of neurones to act as one.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available