The Associative Deficit in Aging: Insights from Task and Resting State Functional Neuroimaging
Year: 2015
Type: dissertation
Study design: Observational Study
Abstract: Human aging is characterized by significant reductions in the ability to remember associations between items, despite having intact memory for single items. In general, neuroimaging studies that investigate the age differences in episodic memory find that older adults show less selective neural recruitment across experimental tasks and weaker resting state functional connectivity (rs-FC) relative to younger adults. However it is unclear whether these neural effects account for older adults’ deficit with associative memory. I used functional magnetic resonance imaging to investigate whether task effects, rest effects, and the dynamic interaction between task and rest relate to the associative deficit. Young and older adults were scanned while at rest and while performing incidental item and associative encoding tasks. As expected, older adults had poorer memory for associations compared to younger adults. In terms of task effects, older adults had less distinct patterns of brain activity during associative encoding and less selective brain activity predicted poorer associative memory. Resting state fluctuations also related to the associative deficit, with older adults showing greater modulation of rs-FC following item and not associative encoding. Furthermore, broader neural recruitment during post-item and post-associative encoding related to better memory. Lastly, older adults failed to show a dissociation between rs-FC in the default and dorsal attention networks and task activity; the lack of dissociation related to associative memory performance and not item memory performance. My results suggest that the associative deficit in older adults results from a lack of distinctiveness in neural activity, which occurs at encoding and is reflected in the interplay between rs-FC and task activity. A subset of higher performing older adults were able to modulate rs-FC in response to task demands and were able to recruit additional neural resources, interpreted as a compensatory mechanism that is engaged to reduce age-related deficits in associative memory.
Source: TSpace (University of Toronto)
Author: Cristina Saverino
Language: English
Subfield: Cognitive Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2605726144