Index of Theta/Alpha ratio to quantify visual - spatial attention in dyslexics using Electroencephalogram

Abstract

Dyslexia is a neurodevelopmental disorder that is characterized by deficits in both phonological and in visual spatial processing. In this study, a visual selective attention task was employed to ten dyslexic’s participants and the brain activation was measured using electroencephalograph (EEG). The mean relative power of the alpha and theta band was computed to calculate theta/alpha ratio. The theta / alpha was significantly higher (p<0.05) during task at temporal lobe and occipital lobe electrode locations than during rest. Parameters including target detection rate as a performance measure was calculated and found to be 59.4±32.4% which is a testimony of their poor performance in orienting and sustaining the visual attention. These cumulatively corroborated the positive correlation between increased theta/alpha ratio in dyslexics during task and their associated deficits in successfully orienting their attention towards the spatially presented target stimuli.