Investigating Pupil Dynamics in Healthy and Clinical Populations

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Date
2024-04-30
Authors
Huang, Po Yueh
Keyword
Eye tracking , Pupillometry , Aging , Parkinson's disease , Pro-anti-saccade , Neurodegenerative disease , Demyelinating disorder , Alzheimer's disease , Dementia , Amyotrophic lateral sclerosis , Frontotemporal dementia , Cerebrovascular disease , Multiple sclerosis , Optic neuritis , Development , Oculomotor system , Eye movement , Pupil response
Abstract
Observing behaviours can provide insight into the underlying functioning of the brain, yielding scientific and clinical utility. The easy-to-measure, involuntary movement of the pupil is under the combined influences of sensory and cognitive processes, including luminance, arousal, sensory-orienting, and executive function, which shift due to changes in the brain across the human lifespan following healthy development and aging as well as clinical disorders. In this thesis, we examined how these changes affect the pupil control circuit and alter pupil behaviour. In the first study, we investigated how the pupil changes across the lifespan related to processes of natural maturation and deterioration in various regions of the brain. Using an oculomotor task that provided sensory cues and engages cognitive control, we assess the processes underlying pupil responses. This study provided insight into the development and aging trajectories of the neural substrates, and established a baseline of normative pupil behaviour to which clinical investigations can be compared. In the second study, we asked how deficits within the pupil circuit affected pupil behaviour by examining pediatric demyelinating disorders. We demonstrated how impairments in sensory and cognitive signalling related to demyelinating injury can affect the latencies of pupil responses associated with structural and functional outcome measures in these disorders. In the final study, we examined changes in pupil behaviour in several neurodegenerative diseases related to the development of dementia. We explored how cognitive impairment is associated with altered pupil responses, and how medications and compensatory mechanisms can affect the pupil in these diseases. Together, these studies give an account of how sensory and cognitive functions can be reflected on the pupil in health and disease. This work will be important for advancing the use of pupillometry in research and clinical applications.
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