Year: 2018
Type: dissertation
Abstract: Converging evidence has demonstrated age-related reductions in the ability to selectively focus on task-relevant information, while simultaneously ignoring task-irrelevant information (i.e., cognitive control). Although reduced cognitive control in older adults is typically associated with deficits in attention and memory, recent work has shown that this cognitive pattern can be advantageous in certain contexts. This thesis investigates how reduced control in older adults is associated with an age-related pattern of benefits and deficits on memory tasks with different demands and characteristics. Studies 1 and 2 explored whether older adults show better performance than younger adults on an implicit memory task that relies on conceptual knowledge of previous irrelevant information. Studies 3 and 4 explored how age differences in cognitive control influence memory for different types of associations, and the neural correlates of that effect. Studies 1 and 2 showed that when exposed to distractor words in the context of an incidental encoding task, older adults displayed a memory advantage for those words when they became relevant on a conceptually based general knowledge task, relative to younger adults. Study 3 showed that older adults had preserved memory for meaningful associations that are consistent with prior knowledge, but not arbitrary associations. Reduced cognitive control, in the form of controlled retrieval, accounted for that age effect. Finally, using functional magnetic resonance imaging (fMRI), Study 4 demonstrated that older adults engaged control regions to a lesser extent than younger adults during the retrieval of arbitrary associations. Moreover, activation of the default network (DN), a set of regions implicated in prior knowledge and commonly less modulated with age due to reduced control, accounted for older adults’ enhanced memory for meaningful associations. In sum, older adults’ pattern of cognition, characterized by reduced cognitive control, was associated with better performance on implicit memory tasks that depend on conceptual knowledge of previous distractors, and preserved memory for meaningful, but not arbitrary, associations.
Source: TSpace (University of Toronto)
Author: Tarek Amer
Language: English
Subfield: Cognitive Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W3151276266