Degrees of relevance? The neuronal representation of sound sources in primary auditory cortex during active localization

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How do we listen to specific talkers within a crowd or localize an individual car in heavy traffic? In everyday life, multiple sound sources are often simultaneously active, yet our brain unravels this mix of sounds into distinct information streams according to the sources of origin. Despite decades of research, a functional understanding of the neuronal mechanisms of this phenomenon, which is termed auditory scene analysis (ASA), remains elusive. Most studies on ASA to date focused on the instant processing of simple sounds in passive (i.e. behaviorally irrelevant) settings and a head-centered (egocentric) reference frame. However, during realistic ASA, there is a continuous modulation of the sensory input. Particularly, since the relative angle between the head and the sound source is constantly changing due to self-motion, a egocentric coding of sound source positions is inadequate. Rather, a representation of absolute (allocentric) sound source location in space would be beneficial. Moreover, ASA is fundamentally characterized by the selective listening to a particular sound source of interest, suggesting that the coding of a sound source likewise depends on its goal-specific relevance.Accordingly, the overall goal of this project is to reveal the neuronal processing and representation of sound source locations during active navigation and its dependency on behavioral relevance. To this end, I developed an ASA paradigm with multiple sound sources, in which freely moving rodents perform selective listening and localization. Using wireless chronic recordings in primary auditory cortex during task performance in this paradigm, I aim to: 1) Determine the nature of spatial representation during active navigation2) Decipher how spatial representations in A1 evolve during the learning of context-specific spatial relevance3) Assess the context-dependency of egocentric representations of behaviourally relevant sound localization cues.