The role of ephrin-A2/A5 in visual system development

Tenelle Wilks

    Research output: ThesisDoctoral Thesis

    446 Downloads (Pure)

    Abstract

    [Truncated abstract] The connections that form between the various specialised sub-regions of the brain are complex, requiring precision in initial localisation, targeting and outgrowth. The visual system is a popular model for understanding how mapping develops in the brain as it involves highly precise point-to-point mapping between regions which handle different aspects of the information. There is also integration between these specialised subregions such that information from the same region of the visual field is co-localised. This topographic mapping requires many factors in order to develop appropriately, and errors are seen in experimental models which eliminate them. The visual field is represented topographically within the superior colliculus (SC) maintaining the strict spatial order present in the retina. Numerous mechanisms establish this topography during development including ephrin-A guidance ligands, patterned retinal activity and visual experience. Previous studies indicated ephrin-A2 and ephrin-A2/A5-/- mice have disrupted retinocollicular projections and ectopic termination zones within the SC. This thesis examines the interaction between ephrin- A2 and ephrin-A5 and the environment following both dark-rearing and environmental enrichment, as well as how these axon guidance molecules are involved in mapping of the ipsilateral retinocollicular projection. To determine the effect normal visual experience has on ephrin-A2/A5 in establishing retinocollicular topography, wild-type, ephrin-A2-/- and ephrin-A2/A5-/- mice were darkreared from birth until adulthood at which point anatomy, electrophysiology and behaviour were investigated. There were an increased number of ectopic termination zones in dark-reared ephrin-A2/A5-/- mice, although this was only seen anatomically. Termination zone size was larger in dark-reared wild-type mice only. Receptive field size of main receptive fields was increased in all dark-reared animals...
    Original languageEnglish
    QualificationDoctor of Philosophy
    Supervisors/Advisors
    • Rodger, Jennifer, Supervisor
    • Harvey, Alan, Supervisor
    Publication statusUnpublished - 2013

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