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A study of the relationship of abnormal reward processing and dopamine signalling in adults with high functioning autistic spectrum disorder

Hassan, Eusra (2009) A study of the relationship of abnormal reward processing and dopamine signalling in adults with high functioning autistic spectrum disorder. Masters thesis, University of Liverpool.

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Introduction: Autistic spectrum disorder (ASD) is a neurodevelopmental condition which is defined by language and communication difficulties, impairment in social skills and restrictive and repetitive patterns of behaviour. Functional deficits have often been observed in individuals with autistic spectrum disorder, which could be partially due to an early failure of the amygdala. Motor activity, attentional skills, social behaviour and perception of the outside world are all implicated in autism and are all also modulated by the neurotransmitter dopamine. Past evidence has suggested that dopamine neuron activation aids a person on learning to identify the association of particular stimuli with reward. Aims: The main objective of this preliminary study is to examine the neural activation during the visualisation of grouped images from the IAPS library in normal participants and to observe if the activation follows a pattern in the neural reward circuitary. Methodology: Participants underwent functional magnetic resonance imaging (fMRI), during which they performed four tasks to test their reward processing; a visual paradigm, in which the participants saw a display of images with differing emotional weightings, a gambling paradigm, a soft touch paradigm and a materials paradigm. The visual paradigm fMRI data was analysed using Brain Voyager version 1.3. Results: The limbic lobe, anterior cingulate gyrus and the frontal lobe were the regions of the brain most activated for all of the visual conditions in the control participants. The ASD participant activated more neural regions, especially the limbic regions, than the control participant in the Case vs. Control comparison. Discussion: Common areas of activation in the control group were the anterior cingulate gyrus, the limbic lobe and the medial frontal gyrus. These areas all modulate facial and image recognition, emotional processes and the evaluation of reward. The ASD participant demonstrated more activation in limbic regions of the brain than the control participant. These results support the idea that individuals with ASD have difficulties in controlling their arousal state and often have high levels of arousal. This can have implications on the processing of rewarding and non rewarding stimuli in people with ASD.

Item Type:Thesis (Masters)
Subjects:R Medicine > RC Internal medicine > RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry
Departments, Research Centres and Related Units:Academic Faculties, Institutes and Research Centres > Faculty of Medicine > School of Reproductive & Developmental Medicine
ID Code:1301
Deposited On:27 Jan 2012 10:58
Last Modified:30 Jan 2012 02:15

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