Cortical mechanisms underlying auditory spatial and non-spatial selective attention
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Despite the importance of auditory selective attention in everyday communication, the cortical mechanisms underlying the amazing ability of human brain to focus on a sound stimulus and suppress others are not well understood. Recent studies have led to the hypothesis that alpha band oscillation (8-14Hz) is a neural signature of multimodal spatial attention. Research in multiple sensory domains has shown that alpha synchronizes in the hemisphere contralateral to unattended stimuli and desynchronizes on the hemisphere contralateral to attended stimuli, suggesting it is a marker of an inhibition process for filtering out unattended stimuli. However, further research is needed to understand the possible functional role of these alpha oscillations as well as their correlation with other cortical activity. Moreover, it is not clear whether different forms of auditory attention employ different cortical mechanisms, mediated through different brain networks. This study aims to combine brain stimulation methods (transcranial Direct/Alternative Current Stimulation) with electrophysiological measurements of electroencephalography (EEG) to measure and interpret the underlying cortical activity during different forms of auditory selective attention. More specifically, there are four studies, each of which employs behavioral tasks to test specific hypotheses. First, we studied alpha oscillatory activity during auditory spatial attention. Second, we compared and contrast cortical activity during auditory spatial and non-spatial attention. Third, we used brain stimulation to see if we can show a causal relationship between alpha oscillation and selective auditory attention performance. Lastly, we applied the existing results on alpha power to use it as a quantitative biomarker to indicate the level of spatial attention network engagement. Our results contributed to the growing body of knowledge about how the brain employs auditory selective attention for effective communication.
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