Year: 2017
Type: dissertation
Abstract: The role of aging on cognitive decline has been looked at with a great deal of interest over the past few decades. To a large extent, the aging literature has focused heavily on the impact of aging on memory and cognitive resources, and one area of literature that remains underdeveloped has been the role on how aging affects the cognitive processes of vision. More specifically â does aging change the activity and mutually inhibitory processes of the magnocellular (M) and parvocellular (P) pathways? In order to test how aging affects these two visual pathways, I implemented techniques known to hinder or bolster the M-pathway in younger adults with older adults. In Experiment 1, I tested if the inhibition of the M-pathway with a pulsed pedestal design also occurs with older adults. In this task, I had younger and older adults perceive low and high spatial frequency Gabors with either a pulsed or steady visual pedestal. In Experiment 2, I examined if the connection between the M-pathway and action processing found in younger adults changes with age. In Experiment 3, I examined the connection between object-based attention and the two visual pathways. Across the first three experiments, older adults showed a greater deficit to the M-pathway in the pulsed pedestal condition than younger adults. In Experiment 4, I examined if placing the hands proximal to visual images, which facilitates M-pathway processing in younger adults, also occurs in older adults. Here I found that older adults showed the opposite effect; greater advantage for low spatial frequency Gabors compared to younger adults when the hands were proximal. The data across all four experiments suggest that older adults may have noisier visual pathways, with larger deficits when the M-pathway is inhibited and larger benefits when the M-pathway is bolstered.
Source: TSpace (University of Toronto)
Author: David Chan
Language: English
Subfield: Cognitive Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2808401621