Friday, May 9, 2025
5/9/2025
Novel subdivisions of the dorsal cortex of the inferior colliculus - The inferior colliculus is a major integration site in the central auditory system. Rate tuning for certain behaviorally-important sound features, such as amplitude modulation, is first elaborated upon in the inferior colliculus, suggesting that it plays an essential role in complex sound processing. Dysfunctional inferior colliculus organization has been seen in a number of disorders of auditory processing, including tinnitus, dyslexia and schizophrenia. Unfortunately, our understanding of IC circuitry, particularly amongst its subdivisions, remains limited. We recently found an unexpected degree of functional heterogeneity in a substructure within the inferior colliculus known as the dorsal cortex (DC). Previous work has suggested that the DC does not have subdivisions or a tonotopic arrangement. However, using two-photon imaging of the DC which allows dense sampling of its surface, our group and others have found two mirror-image tonotopic maps on the DC surface. These maps divide the DC into a lateral portion (DCL) and a medial portion (DCM). We have further found that the DCL shows strong preferences for amplitude-modulated white noise, whereas the DCM shows preferences for pure tone unmodulated sounds. These data suggest that there may be at least two functionally distinct nuclei within the DC. Here, we will further characterize these functional differences between DCM and DCL and will determine if there are differences in response properties to complex sounds, and will determine if DCM and DCL show differential plastic responses to noise exposure. Successful completion of this work has the potential to add clarity to our currently murky understanding of the role of the DC in auditory processing and potentially to define new brain subregions in this structure. More broadly, given the importance of the inferior colliculus in auditory processing, this work will provide additional insights into the general organization architecture of the inferior colliculus which will facilitate a greater understanding and targeted therapies for its disorders.
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