Role of CaV1.3 in generation and development of complex neuronal activity in the mouse auditory cortex

Jan Hirtz – Timo Mühlhaus – Christoph Garth

The calcium channel Ca_V1.3 is essential for functionality of the inner ear. However, hearing impairments and developmental aberrances of the central auditory pathway are also observed in conditional brainstem-specific Ca_V1.3 knockout mice with normal inner ear function. To investigate the role of central Ca_V1.3 for development and function of the auditory system, we perform in vivo activity imaging in the auditory cortex of brainstem- and forebrain-specific knockout mice. We employ two-photon calcium imaging, which provides single cell resolution, while recording activity of up to a few hundred neurons in one field of view. Pure tone acoustic stimulations are used to determine basic response properties of neurons in the auditory cortex, addressing e.g. tonotopy. In addition, complex acoustic stimulations are used to evoke multilayered activity patterns in the auditory cortex of knockout mice and control littermates. We are developing software tools to analyze the resulting fluorescence recordings, including automatic identification of active neurons as well as separation of spatially overlapping calcium signals. Subsequently, neuronal activity is inferred from the resulting traces. Further analyses aim to identify activity patterns in the population data. The results obtained in this project will lead to new insight into the information processing in the normal and maldeveloped auditory system.