Temporal expectations in healthy ageing & neurological disorders

Previous research has shown that orienting attention in time can help to improve behavioural outcomes. However, the extent to which temporal orienting can be preserved in ageing and in the context of neurological disorders remains unresolved. This thesis therefore explores temporal expectations in the healthy ageing and diseased brain by taking a neuropsychological approach. To begin, I provide an overview of the literature in Chapter 1 most relevant for the following investigation. Four chapters of experiments then follow. To examine the effects of ageing on temporal expectation, the performance of healthy young adults and healthy older adults is presented and the results are discussed in Chapter 2 and 3. Though it had been previously shown that older adults seem to experience an expectation deficit on temporal expectation tasks, these chapters demonstrate the preservation of temporal expectation in ageing. On their own, these findings represent an important and novel contribution to the literature; however, this research is incapable of establishing the causal mechanisms involved in temporal expectation. To explore the causal role of relevant brain regions in temporal expectation, Chapter 4 and 5 investigate the effects of temporal orienting in participants with damage to the basal ganglia â a brain region strongly implicated in temporal processing. In Chapter 4, the role of the basal ganglia in temporal expectations is examined using data collected from participants with Parkinsonâs disease and contrasts their performance with age-matched healthy controls. To complement this investigation, and to provide converging evidence for the basal gangliaâs role in temporal expectations, Chapter 5 investigates the behavioural performance of individuals with focal lesions to the basal ganglia. The findings in this thesis are discussed in their wider context in Chapter 6, and directions for future research are proposed.