In this thesis, allocentric spatial memory was investigated in healthy volunteers with average and high levels of schizotypal traits assessed using the Schizotypal Personality Questionnaire. Functional and structural MRI was used to investigate the neural correlates of allocentric spatial memory in schizotypal personality. Allocentric spatial memory is reported to be impaired in schizophrenia and this is thought to be related to alterations in hippocampal function and structure. Previous literature suggests individuals with schizotypal personality traits have a similar cognitive and neural profile to schizophrenia spectrum disorders for example reduced hippocampal volumes and compromised cognition. It was therefore hypothesised that high schizotypy would be associated with worse performance on these tasks and a different pattern of functional activation in the hippocampus and parahippocampal gyrus compared to controls. No behavioural differences were observed on the cognitive measures in this thesis. Investigation of brain function revealed decreased volume of the right hippocampus and bilateral medial frontal gyrus and increased volume of the posterior cingulate, superior temporal gyrus and anterior prefrontal cortex, in line with previous literature. Functional MRI revealed decreased activation of the right hippocampus during memory encoding and increased activation of the hippocampus bilaterally during memory retrieval in high schizotypy compared to controls. Memory retrieval was also associated with increased activation of the anterior cingulate gyrus, inferior frontal gyrus and insular cortex in this group. Further, activation of the right hippocampus is related to better performance across allocentric spatial memory tasks in controls but this relationship is absent in high schizotypy.
|Date of Award
|1 May 2012
|Steven Williams (Supervisor) & Robin Morris (Supervisor)