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Neural correlates of visual perceptual learning and inhibitory neurotransmitter in humans using magnetic resonance spectroscopy

Garcia, Adrian Dante (2017)
Ph.D. thesis, University of Birmingham.

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Abstract

The role of excitatory processes in human visual learning has been well characterised through the use of technologies such as functional magnetic resonance imaging (fMRI). However, established imaging modalities do not distinguish excitatory processes from the inhibitory ones that are also involved. Here we investigate inhibitory processes using magnetic resonance spectroscopy (MRS) and the MEGA-PRESS pulse sequence. We measure concentrations of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) in different brain regions as functional markers of inhibitory potential. We then investigate the correlations between GABA concentrations and psychophysical learning metrics. We detail a full analysis pipeline that improves the accuracy of in vivo GABA quantification and introduce new scaling methods to resolve the grey matter contribution to metabolite measurements. We develop visual learning experiments that are mediated by training difficulty, which we link to inhibitory processes across different time scales. We also present novel evidence for GABAergic inhibitory mechanisms across multiple brain areas using fine and coarse discrimination tasks. Our results support a cooperative top-down and bottom-up model of visual learning in occipital and frontal cortical regions. Our findings reveal chemical interactions with cognition to contribute to our understanding of inhibitory processes in the human learning brain.

Type of Work:Ph.D. thesis.
Supervisor(s):Arvanitis, Theodoros N. and Davies, Nigel and Kourtzi, Zoe and Peet, Andrew
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:PSIBS Doctoral Training Centre
Subjects:BF Psychology
QC Physics
QP Physiology
RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry
Institution:University of Birmingham
ID Code:7770
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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