Association between cortical hyperexcitability and visual disturbances – evidence from behaviour and electroencephalogram

Fong, Chun Yuen (2019). Association between cortical hyperexcitability and visual disturbances – evidence from behaviour and electroencephalogram. University of Birmingham. Ph.D.

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Abstract

This thesis presents four studies that sought to examine the presence and role of cortical hyperexcitability underlying aberrant / anomalous perceptions in neurotypical and self-reported migraine groups. The current thesis developed new screening tools for assessing and conceptualising cortical hyperexcitability leading to essential advancements in our understanding of its presence and its role in different forms of anomalous experience.
In chapter II, the latent structure of a proxy measure was uncovered and constructed to reflect cortical hyperexcitability, namely Cortical Hyperexcitability Index – II (CHi-II), by conducting an exploratory factor analysis on the behavioural data that indicates the frequency and intensity of the 300 non-clinical participants’ everyday life anomalous visual experiences.
In chapter III, a revised pattern glare test was employed to investigate a direct linkage between everyday life visual stress symptoms and pattern glare. The quantitative analyses were implemented by exploring the statistical relationships between the scores of the extracted factors on CHi-II and pattern glare scores and on a set of migraine patients and healthy controls.
In chapter IV, where the gratings typically used in a pattern glare test were revised as visual stimuli with a VEP paradigm. The association between cortical hyperexcitability and pattern glare was examined by electrophysiological measurement. Here the early (0 – 200 ms) and late VEP (300 –700 ms) components are compared between the groups of self-reported migraineurs and neurotypical participants.
Finally, aiming to isolate the effect of cortical hyperexcitability from migraine, the above VEP study on a clinically normal sample was replicated in chapter V. In order to observe how cortical hyperexcitability may influence the VEPs, non-clinical subjects were split into hyperexcitable and non-hyperexcitable based on their pattern glare scores. The early and late VEP components are, again, compared between these two groups.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):