Working memory in healthy ageing

This thesis is concerned with the age-related changes in working memory (WM), and the inter-individual differences in cognitive and neural mechanisms that correspond to healthy versus poor ageing of WM function. The first half of this thesis focusses on the age-related decline in WM and whether preserved top-down attentional control could mitigate such deficits. In Chapter 2, I present a functional MRI study showing that older adults reliably recruit brain networks that subserve cognitive control, which work in concert with the task relevant sensory areas during effective selective WM. In Chapter 3, I show that older adults retain flexible control over WM representations, and this ability corresponded to the reliable recruitment of neural signals of orienting attention qualitatively similar to those observed in younger adults. Magnetoencephalographic recordings showed that the neural dynamics during orienting attention within WM was predictive of good performance, demonstrating that the more efficient the process of orienting within WM to select the target item, the better the memory representation can be preserved for upcoming behaviour. In the second half of this thesis, I explored whether WM for affective content has a special status in healthy ageing. In Chapter 4, I developed an emotional WM precision task to measure WM abilities for emotional content appropriate for elderly adults. In Chapter 5, I tested a group of young and older adults on WM and perceptual-matching abilities for emotional faces. The results suggest that older adults show a general impairment in task performance, but possibly with some preservation in the ability to maintain emotional content in WM. There were marked differences in how the emotional information was processed between age groups, in which older adults have a tendency to represent negative stimuli as less negative than younger adults in perception and WM, and tended to show a positive interpretation of the valence of more ambiguous emotional stimuli. In Chapter 6, I summarise the findings presented in this thesis, discuss the implications of the key findings, and consider some suggestions for future studies that aim to elucidate the mechanisms of WM in healthy ageing.