Understanding the brain mechanisms that regulate attention to auditory memory

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Human oral communication is constrained by our ability to “hear” a speaker even in the presence of other noise, whether that be other people talking or other sound sources (e.g., music, mechanical engine sounds). Doing this often requires a sort of replay of what a person just said by going back in one's mind to those spoken words still accessible in short-term memory. That is, the sounds just heard, but no longer present, become the object of our attention. We know that selective attention influences what we remember, and that it is easier to understand a familiar talker than an unfamiliar one. However, we do not fully understand the brain mechanisms that allow us to attend to sounds in short-term memory nor do we know how existing memories bias that attention. The aims of this research program are to: (i) characterize the neural architecture that allows people to focus their attention to auditory memory; (ii) determine how brain processes differ when listeners are reflecting on the when, what, or where of the sound just heard; (iii) examine how attention to memory enhances processing of degraded speech; (iv) characterize how long-term memory steers attention; and (v) identify how information in long term memory is integrated with ongoing perceptual processing in adverse listening conditions. All studies include healthy young adults and implement a careful combination of behavioral, computational, and brain imaging techniques in order to map out the time course and brain areas involved in these processes. Top-down attention to short-term memory is studied using what is called a delayed match-to-sample paradigm. In such tasks, a (retro)cue telling participants which item(s) to maintain in memory (internally oriented attention) appears after the stimulus array is presented. We predict that attention to memory will engage a widely distributed neural network of brain regions that include the auditory cortex and regions important for focusing attention. The interplay between attention and auditory long-term memory is investigated using a learning paradigm designed to create a strong association between two auditory stimuli. We anticipate that existing contextual memories will bias attention and optimize perception by re-activating brain areas originally involved during learning. The results will allow us to advance models of attention by taking into account the proper and changing balance of attending to events from our internal and external worlds. Determining how attention is allocated to auditory memory can guide the development of training regimens to improve attention in normal populations across the life span and also in people within brain damage, medical conditions and/or learning disabilities which affect their ability to attend to memory.**