Effects of Neural Dedifferentiation on the Selectivity of the Magnocellular and Parvocellular Visual Pathways
Open Access
- Author:
- Elbich, Daniel Benjamin
- Graduate Program:
- Psychology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- June 17, 2020
- Committee Members:
- Nancy Anne Coulter Dennis, Dissertation Advisor/Co-Advisor
Nancy Anne Coulter Dennis, Committee Chair/Co-Chair
Bradley Paul Wyble, Committee Member
Reginald Adams, Jr., Committee Chair/Co-Chair
Chaleece Wyatt Sandberg, Outside Member
Kristin Ann Buss, Program Head/Chair
Reginald Adams, Jr., Dissertation Advisor/Co-Advisor - Keywords:
- fmri
aging
mvpa
vision
expression
threat detection - Abstract:
- One of the most marvelous aspects of the brain is that areas can be specialized to a specific duty or function. Importantly, functional specialization is widespread in the brain and can be observed in multiple different areas of cognition, especially in domain visual processing, However, across the lifespan research has identified a process known as neural dedifferentiation, whereby this specialization in brain regions declines and become less specialized for their function. In this project, I employed state-of-the-art multivariate neuroimaging methodologies to address the following questions: 1) Are there detectable differences in the neural patterns of Magnocellular and Parvocellular biased stimuli, 2) Do these patterns exhibit age-related dedifferentiation their neural response, 2A) Do patterns of dedifferentiation shift in posterior brain regions, 2B) Is there age-related dedifferentiation in the neural responses to Unbiased stimuli, 2C) Is there age-related dedifferentiation in the neural responses to facial expression, and 3) Does this dedifferentiation impact ability to detect threat in either or both visual pathways? I used a previously collected dataset of 102 adult participants spanning 60 years of healthy aging originally collected to measure threat detection. I performed multivariate pattern analyses (MVPA) to determine whether neural representations for visually biased stimuli differed along two primary visual routes, the magnocellular and parvocellular visual pathways. Secondly, these representations were interrogated to determine robustness across healthy aging. Finally, neural patterns for visually stimuli were tested for their relation to detecting facial threat. Overall the results show that neural patterns for visually biased stimuli can be observed in both the magnocellular and parvocellular visual pathways, particularly in anterior frontal and ventral temporal areas of the brain. However, there is little evidence suggesting these representations become less distinct over time or influence threat detection, suggesting that dedifferentiation may not be as ubiquitous as previously thought. This research is the first of its kind to merge visual pathway biasing, multivariate pattern classification, dedifferentiation, and social perception.