title: Cortical hyperexcitability and sensitivity to discomfort glare.
abstract: It is well established that there are two main aspects to glare, the visual impairment and the discomfort, known as disability and discomfort glare, respectively. In contrast to the case of disability glare we understand very little about the underlying mechanisms or physiology of discomfort glare. This study attempts to elucidate the neural mechanisms involved using fMRI and glare sources with controlled levels of retinal illuminance. Prior to carrying out the fMRI experiment, we determined each participant's discomfort glare threshold. The participants were then divided into two groups of equal size based on their ranked sensitivity to discomfort glare, a low and high sensitivity group. In the fMRI experiment each participant was presented with three levels of glare intensity whilst simultaneously required to carry out a simple behavioral task. We compared BOLD responses between the two groups and found that the group more sensitive to glare had an increased response that was localized at three discrete, bilateral cortical locations: one in the cunei, one in the lingual gyri and one in the superior parietal lobules. This increased response was present for all light levels tested, whether or not they were intense enough to cause discomfort glare. Based on the results, we present the case that discomfort glare may be a response to hyperexcitability or saturation of visual neurons.
authors: Applied Vision Research Centre, School of Health Sciences, City University London, Northampton Square, London EC1V 0HB, UK. Electronic address: gary.bargary.1@city.ac.uk.
authors: Gary
authors: G
authors: Bargary
authors: Department of Psychology, Royal Holloway University of London, Egham Hill, Egham TW20 0EX, UK.
authors: Michele
authors: M
authors: Furlan
authors: The UCL Institute for Environmental Design and Engineering, University College London, Gower Street, London WC1E 6BT, UK.
authors: Peter J
authors: PJ
authors: Raynham
authors: Applied Vision Research Centre, School of Health Sciences, City University London, Northampton Square, London EC1V 0HB, UK.
authors: John L
authors: JL
authors: Barbur
authors: Department of Psychology, Royal Holloway University of London, Egham Hill, Egham TW20 0EX, UK.
authors: Andrew T
authors: AT
authors: Smith
mesh_terms: D000328:Adult; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology; D005260:Female; D019466:Glare / Q000009:adverse effects*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D010146:Pain / Q000503:physiopathology*; D010775:Photic Stimulation; D012720:Severity of Illness Index; D014796:Visual Perception / Q000502:physiology*
chemical_list: D010100:Oxygen