Dr. Rosanna Smith
Structure and function of the avian neuronal nucleus for sound localisation
In this thesis I present studies on the structure, function and development of the avian neuronal nucleus for sound localisation. The ability to locate sound sources is an important faculty for both predator and prey alike and the precision of sound localisation ability is known as acuity. Using theoretical methods I have determined that there is a limitation on acuity for sound localisation using interaural time difference (ITD) detection. For a given head size and speed of sound, acuity is limited by the geometry between a sound source and listener. The form of ITD detection mechanism can not overcome the angular variation of acuity due to a baseline ITD detection error. This has implications for ITD detection structures. In birds, the nucleus Laminaris (nL) is a population of ITD detecting neurons with an unusual laminar structure. I have investigated nL structural development from a rounded cluster of cells to a one cell thick sheet.
The structure and function of cell populations are interlinked and their relationship can be investigated through understanding their development. These studies show that cell death is not a significant contributor to nL structural development and relative cell movement is the dominant mechanism. There is also spatiotemporal patterning of nL structure development which is similar to the patterning found for neuron birth times. Intercellular interactions, such as adhesion, can affect relative cell movements during development. By considering the maximum adhesion configuration for a theoretical population of cells, I have demonstrated that population structure can be affected by individual cell morphology. This may provide a mechanism for nL laminar structure development. The role of adhesion in nL development and cell migration has also been explored using in vivo perturbation and in vitro assays.
Next employment after CoMPLEX:
Research Associate at the Department of Cell and Developmental Biology, UCL
- Smith, R. and Price, S. Uniform precision of interaural time difference identification in humans. Submitted
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