Laminar Distribution of stimulus- and task-related variables related to auditory streaming in core and belt auditory cortex

Abstract

AbstractHumans and non-human animals parse the auditory scene into distinct auditory objects or “streams” by grouping together stimuli with common features and segregating those with different features. This process is commonly called “auditory scene analysis”. Although previous studies have identified neural mechanisms in the primary (core) auditory cortex that may underlie auditory-stream segregation, we do not have a good understanding of the contribution of cortical regions outside of the core auditory cortex to stream segregation nor do we understand the laminar specificity of these contributions. To examine these issues, we recorded translaminar multiunit activity (MUA) from the core and belt auditory cortex in macaque monkeys while they participated in an auditory streaming task designed to provide an objective measure of auditory-stream segregation. We found that MUA encoded both the stimulus variables and the monkey’s behavioral choices related to our streaming task. Overall, core MUA was modulated more by the stimulus variables and the monkey’s choices than belt MUA. However, whereas neural correlates of these variables were uniformly distributed in the core auditory cortex, stimulus- and choice-related information was predominantly represented in the superficial and deep layers of belt, respectively. These findings support a differential representation of stimulus- and choice-related variables related to auditory scene analysis along the primate auditory cortical pathway.Significance StatementAuditory-stream segregation is a fundamental component of auditory scene analysis. To our knowledge, this is the first study to examine the neural correlates of auditory-stream segregation outside of the core auditory cortex in macaque monkeys and the first to examine the laminar specificity of these neural correlates. We recorded neural responses while monkeys performed a new task for non-human primates designed to objectively test auditory-stream segregation. We found that neural responses reflecting stimulus- and behavior-related variables (i.e., the monkeys’ choices) were differentially represented in the core and belt regions of the auditory cortex and across different cortical layers. These findings support a non-uniform representation of stimulus- and behavior-related variables related to auditory scene analysis along the primate auditory cortical pathway.