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Dave Saint-Amour, Karine Lacourse, Mathieu Simard, Sarah Lipppé; Entropy estimation of resting-state EEG variability in amblyopia. Journal of Vision 2015;15(12):654. doi: 10.1167/15.12.654.
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© ARVO (1962-2015); The Authors (2016-present)
Human EEG studies have shown that development of visual processing is associated with changes in entropy, i.e., signal variability. In the present study we asked whether abnormal development associated with amblyopia alters brain signal entropy at adulthood. Brain’s electrical resting state activity was recorded from occipital (Oz), central (Cz) and frontal (Fz) sites in 6 strabismic adults (mean age = 32 y) and 9 controls (mean age = 30 y) under monocular and binocular viewing conditions. Wavelet decomposition was applied to the EEG to extract 9 scales or frequency bands. Shannon entropy estimation as a measure of irregularity or variability of the signal was calculated for each frequency band. Results revealed no significant difference between the dominant and non-dominant eyes for the controls and, more surprisingly, the amblyopes. However, entropy was significantly different between groups for the frequency bands below 30 Hz at all electrodes, in particular theta band (3.9-7.8 Hz) at Oz. No significant difference between groups was found for binocular signals, although entropy was slightly higher in the amblyopes. These findings suggest that entropy can be a useful metric to better assess the nature of brain processing in amblyopia, not only for the amblyopic eye but also the fellow eye, which might also be associated with abnormal processing, as far as signal variability is concerned. Further research is needed to confirm these results on a larger number of participants and to link entropy to visual dysfunctions reported in amblyopia, either at neural (e.g., oscillatory synchronisation) or behavioural level, to improve our understanding of the underlying mechanisms.
Meeting abstract presented at VSS 2015
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