Multi-Color Channelrhodopsin-Assisted Circuit Mapping of Auditory Inputs to a Novel Class of Stellate Cells in the Mouse Inferior Colliculus

• Applicant: Dr. David Goyer
• Subject Area: Molecular Biology and Physiology of Neurons and Glial Cells
• Term: from 2018 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 401540516

The inferior colliculus (IC), the midbrain center of the auditory pathway in mammals, is the first major hub of the auditory system, as virtually all information from the lower auditory brainstem nuclei converges in the IC. But despite the IC’s prominent position in the auditory system and its crucial function in the auditory pathway, we still have fundamental gaps in our knowledge of individual cell types and the organization of neural circuits in the IC. This has substantially hindered progress in understanding how the IC processes sounds. Recently, evidence has been found that the IC is a major site of plasticity following hearing loss, but it remains unclear if this plasticity is beneficial to recover normal hearing or a pathological process. A major roadblock to a deeper understanding of the IC has been that with standard techniques, it has not been possible to define distinct cell types in the IC, a prerequisite to understand how the IC can encode diverse sounds and how the IC’s output is shaped. Additionally, it is imperative to know how those different cell types are integrated in the IC’s microcircuitry, as well as how they are integrated in the ascending and descending auditory pathway. In this fellowship, these issues will be addressed by investigating how a newly identified subgroup of IC stellate cells, so-called VIP Neurons, are integrated into the IC’s circuitry. By using channelrhodopsin assisted circuit mapping, the physiological impact of synaptic inputs from commissural projections and from auditory brainstem nuclei to VIP neurons will be assessed. Additionally, it will be investigated how those inputs are integrated by the neurons and how this shapes the neurons excitability and output. This will ultimately lead to a more comprehensive understanding of how the IC detects and processes diverse sound features, and how this can be harnessed to better understand and treat hearing loss on the midbrain level.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professor Michael T. Roberts, Ph.D.