Analysis of patterns of neural activity in response to auditory stimuli

Abstract

It is usually easy to understand speech, but when several people are talking at once it becomes difficult. The brain must select one speech stream and ignore distracting streams. This thesis tested a theory about the neural and computational mechanisms of attentional selection. The theory is that oscillating signals in brain networks phase-lock with amplitude fluctuations in speech. By doing this, brain-wide networks acquire information from the selected speech, but ignore other speech signals on the basis of their non-preferred dynamics. Two predictions were supported: first, attentional selection boosted the power of neuroelectric signals that were phase-locked with attended speech, but not ignored speech. Second, this phase selectivity was associated with better perception for the attended speech. We also describe a novel analysis of neuroelectric responses in complex auditory scenes, and suggest a new model of auditory distraction that is consistent with some unexpected results.