A Multimodal Investigation of Age Differences in Inhibitory Control

Cognitive control – a set of mental processes that allow us to perform goal-directed actions and flexibly adapt our behavior under changing circumstances – is reduced in aging. Older age is also accompanied by changes in the structure and functioning of the frontoparietal network that supports cognitive control processes. This thesis examines the relationship between the white matter properties and functional recruitment of the frontoparietal network and their association with performance on cognitive control tasks in healthy aging. In a large, cross-sectional lifespan sample of adults, the first chapter explores the microstructural and macrostructural properties of frontoparietal white matter and its association with performance in three domains of cognitive control: working memory, inhibitory control, and updating ability. White matter microstructure (i.e., fractional anisotropy, FA) was associated with age-related reductions in response inhibition, as assessed by the go/no-go task. Based on the notion that brain function is constrained by the underlying anatomy, the second chapter investigates whether FA influences task-related activation (i.e., BOLD activity) of the frontoparietal network during inhibitory processing, as well as the joint contribution of frontoparietal FA and its functional recruitment to age-related differences in response inhibition. Frontoparietal FA was not related to BOLD activity, but it mediated age-related differences in go/no-go response times that in turn influenced age-related differences in accuracy. Thus, it appears that the microstructure of the frontoparietal network bears greater relevance than functional recruitment for explaining age-related differences in response inhibition. Lastly, the third chapter examines whether age differences in inhibitory control influence other aspects of cognition, namely, recognition memory. Inhibitory control was measured in two ways: through the ability to fixate (i.e., oculomotor control) and the ability to inhibit visual distraction (i.e., distractor suppression). Older adults were just as efficient as younger adults at inhibiting distraction, resulting in similar levels of subsequent distractor recognition between the two groups. Nonetheless, older adults still showed poor oculomotor control compared to younger adults. Altogether, this thesis demonstrates the heterogeneity in cognitive control processes as well as the neural correlates supporting one domain of control, namely, response inhibition, across the adult lifespan.

Department dc:contributor.department

Psychology

Year dc:date.issued

2023

Author dc:creator

• Parimoo, Shireen

Advisors dc:contributor.advisor

• Olsen, Rosanna K
• Grady, Cheryl

• aging
• cognitive control
• eye-tracking
• fMRI
• inhibitory control
• tractography

Statement dc:rights

• Attribution 4.0 International

Licence dc:rights.uri

• http://creativecommons.org/licenses/by/4.0/

Handle dc:identifier.uri

http://hdl.handle.net/1807/130027

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/130027