IRUS Total

Information processing in visual systems

File Description SizeFormat 
Saleem-A-2010-PhD-Thesis.pdf49.42 MBAdobe PDFView/Open
Title: Information processing in visual systems
Authors: Saleem, Aman
Item Type: Thesis or dissertation
Abstract: One of the goals of neuroscience is to understand how animals perceive sensory information. This thesis focuses on visual systems, to unravel how neuronal structures process aspects of the visual environment. To characterise the receptive field of a neuron, we developed spike-triggered independent component analysis. Alongside characterising the receptive field of a neuron, this method provides an insight into its underlying network structure. When applied to recordings from the H1 neuron of blowflies, it accurately recovered the sub-structure of the neuron. This sub-structure was studied further by recording H1's response to plaid stimuli. Based on the response, H1 can be classified as a component cell. We then fitted an anatomically inspired model to the response, and found the critical component to explain H1's response to be a sigmoid non-linearity at output of elementary movement detectors. The simpler blowfly visual system can help us understand elementary sensory information processing mechanisms. How does the more complex mammalian cortex implement these principles in its network? To study this, we used multi-electrode arrays to characterise the receptive field properties of neurons in the visual cortex of anaesthetised mice. Based on these recordings, we estimated the cortical limits on the performance of a visual task; the behavioural performance observed by Prusky and Douglas (2004) is within these limits. Our recordings were carried out in anaesthetised animals. During anaesthesia, cortical UP states are considered "fragments of wakefulness" and from simultaneous whole-cell and extracellular recordings, we found these states to be revealed in the phase of local field potentials. This finding was used to develop a method of detecting cortical state based on extracellular recordings, which allows us to explore information processing during different cortical states. Across this thesis, we have developed, tested and applied methods that help improve our understanding of information processing in visual systems.
Issue Date: Dec-2009
Date Awarded: Jan-2010
URI: http://hdl.handle.net/10044/1/5531
DOI: https://doi.org/10.25560/5531
Supervisor: Schulz, Simon
Sponsor/Funder: Gatsby Charitable Foundation
Author: Saleem, Aman
Department: Bio-engineering
Publisher: Imperial College London
Qualification Level: Doctoral
Qualification Name: Doctor of Philosophy (PhD)
Appears in Collections:Bioengineering PhD theses

Unless otherwise indicated, items in Spiral are protected by copyright and are licensed under a Creative Commons Attribution NonCommercial NoDerivatives License.

Creative Commons