Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Doctor of Philosophy

Program

Neuroscience

Supervisor

MacDonald, Penny A.

2nd Supervisor

Owen, Adrian M.

Co-Supervisor

Abstract

Humor processing is thought to involve two distinct components. The first, humor comprehension, involves detecting and resolving incongruities that are present within a humorous stimulus. This is related to cognitive processes such as ambiguity resolution, response inhibition, working memory, and cognitive flexibility, functions that are mediated in part by the dorsal portion of the striatum (DS). Humor appreciation, on the other hand, refers to the subjective amusement and mirth that one experiences in response to a joke. This is related to reward processing, which implicates the ventral portion of the striatum (VS). Across three separate studies, we investigated the involvement of the DS and the VS in humor comprehension and appreciation (Chapter 2), the effects of aging on humor comprehension and appreciation and associated neural activation (Chapter 3), and finally, whether Parkinson’s disease (PD), the medication used to treat it, or the interaction between the two, influences humor comprehension and/or appreciation (Chapter 4). We found that in healthy young adults, the DS and the VS are implicated in humor comprehension, and the VS, but not the DS, is implicated in humor appreciation. We also found that humor comprehension ability is negatively affected by age, and that decreases in humor comprehension were related to reductions in DS activation in healthy older adults. Finally, we found that there is a humor comprehension deficit associated with PD that was not improved by dopaminergic medication.

Summary for Lay Audience

Humor is a complex process that involves two main components, supported by different parts of the brain: humor comprehension and humor appreciation. Humor comprehension refers to the ability to understand and resolve jokes, while humor appreciation refers to the subjective experience of finding something funny and feeling amused. The brain is highly interconnected with a region known as the striatum, which can be separated into two parts based on functional and anatomical differences. The first, the dorsal striatum (DS) is involved in problem-solving, while the second, the ventral striatum (VS) is associated with processing pleasurable rewards. In the research described in this dissertation, three separate studies were conducted to investigate the roles the DS and VS in humor comprehension and appreciation, the impact of aging on these processes, and how Parkinson's disease (PD) and its treatment affect humor processing.

Our findings revealed that in healthy young adults, the DS and the VS are involved in humor comprehension. With regards to aging, our research showed that humor comprehension abilities decline with age. Older adults exhibited reduced activation in the DS, indicating that changes in brain activity may contribute to the decrease in humor comprehension. Finally, we found that individuals with PD have deficits in humor comprehension that are not improved by PD medication.

Overall, these findings shed light on the brain mechanisms underlying humor processing and provide insights into how aging and Parkinson's disease can affect our ability to comprehend and appreciate humor.

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