Electrophysiological correlates and consequences of selective auditory attention

The sensory and perceptual mechanisms of the human brain can be reconfigured so as to optimize the processing of a selected type or class of information (i.e. frequency, location, etc.). A foundational goal of cognitive neuroscience is to pursue an understanding of the neural processes that underlie this reconfiguration. Auditory selective attention has been the topic of considerable investigation, principally by the use of event-related potential (ERP) techniques to record certain electrophysiological correlates of attentional selection. The large majority of this work has focused on a single paradigm, known as the sustained-attention paradigm, in which listeners continuously focus their attention at a particular location or on a particular frequency of sound. Only a very few previous studies have investigated the more realistic situation in which listeners continuously reorient their attention on a moment-by-moment basis. This thesis reports the systematic investigation of transient auditory attention. The ERP technique was used to address questions regarding the neural correlates and functional anatomy of auditory selective attention in a variety of situations in which attention was continuously reoriented in space. Following a brief introduction and review in Chapter One, Chapter Two reports the result of the first high-density (64-electrode) study of the ERP correlates of transient spatial auditory attention. This chapter concludes with the speculation that transient attention modulates neurons within a dedicated spatial processing or “where” pathway that projects posteriorly and dorsally from auditory cortex. Chapter Three checks the assumptions of this hypothesis by identifying an ERP correlate of spatial processing and localizing the generator of this correlate to a region of cortex believed to constitute part of this “where” pathway. Finally, Chapter Four reports the results of several experiments that localized certain attention-related modulations of the ERP to this putative “where” pathway. These experiments also demonstrated that transient auditory attention involves a complex interaction between stimulus-driven and goal-driven (bottom-up and top-down) processes that lead to distinctly different patterns of ERP activity. The thesis concludes with a discussion of the advancements made, relative to the state of previous knowledge, as a result of the work presented here.