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Title: Information processing and distribution in the fly early visual system
Author: Li, Xiaofeng
ISNI:       0000 0004 2722 9083
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2011
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Evolution shapes biological systems to better match their desired functions. Hence, we can assume that sensory systems are adapted to optimize information processing. Nevertheless surprisingly little is known about how sensory systems are optimised, or organised, in relation to the information sampling and processing they perform. In particular, our understanding is limited on certain fundamental issues: (1) what are the roles of individual ionchannels in coding information in specialised neural networks, (2) how does information transfer through synapses, and (3) how are different types of information (motion/colour) routed and processed for higher order visual functions. Dipteran compound eyes provide highly useful model systems for examining the basic mechanisms involved in visual information processing; in particular, for assessing how graded potentials code visual information. For this thesis, I have performed extracellular and intracellular recordings from photoreceptors and their primary interneurones, large monopolar cells (LMC), in Calliphora and Drosophila, to investigate the three essential questions mentioned above. This thesis provides systematic characterisations of: (1) Drosophila dSK channels, small conductance calcium-activated potassium channels; (2) Adapting dynamics of postsynaptic quantal bumps in the first visual synapse in Calliphora; (3) in vivo spectral sensitivities of Drosophila R1-R6 photoreceptors and LMCs in wild-type and in selected mutant and transgenic flies. Together with collaborations inside/outside our laboratory, my study: (1) identified the functional roles and gain control of dSK channels in the first synaptic circuits in the fly eye and also clarified how intrinsic activities of neural network compensates for missing or faulty ion channels; (2) characterised how postsynaptic unitary voltage events (or bumps) adapted dynamically to maximize the rate of information transfer at the fly first visual synapse; 3) provided the first in vivo spectral sensitivity functions of Drosophila R1-R6 photoreceptors and LMCs, and demonstrated that functional inputs, from photoreceptors that have different spectral sensitivities, improve motion discrimination and robustness of perception.
Supervisor: Juusola, Mikko Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available