Functional and molecular profiling of cell diversity and identity in the central auditory system: Patch-seq in a sound localization nucleus

• Applicant: Professor Dr. Eckhard Friauf
• Subject Area: Cognitive, Systems and Behavioural Neurobiology ; Molecular Biology and Physiology of Neurons and Glial Cells
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 453200059

The brain is like a kaleidoscope. It consists of countless cells that vary structurally and functionally. A comprehensive knowledge about the cell types is imperative to understand brain function. However, our knowledge of cellular diversity and identity is far from being complete. The present project will unravel the biophysical, anatomical, and genetic determinants of neuronal heterogeneity in the lateral superior olive (LSO). This nucleus is a prominent integration center in the mammalian auditory brainstem and involved in sound localization. By means of single-cell RNA sequencing via the Patch-seq methodology, we aim to identify cell type-specific molecular signatures and to generate a comprehensive neuron type atlas with genome-wide expression data. We reason that functional and anatomical cell-to-cell variability is causally reflected by differences in the transcriptome profile. Our single-cell analyses will obtain an unbiased view of the mRNA present in a given neuron. Unsupervised explorative data analysis will therefore be a major part of our bioinformatics-based approach. We expect to expand the spectrum of neuron types in the LSO by finding hitherto undetected subpopulations. Our project will also include targeted hypothesis-driven analyses. We hypothesize that biophysical parameters correlate with marker genes (e.g. a low input resistance). Another example are membrane time constants, which are crucial for synaptic integration, an utterly important aspect in sound localization. We further hypothesize that genes relevant to neuronal physiology are spatially differentially expressed along the tonotopic axis of the LSO, with several of them in opposing gradients. The transcriptome analyses will be flanked by histological and electrophysiological investigations. Our proposal is submitted in the format of a ‘package proposal’, together with a proposal by Felix Felmy. The interaction enables us to combine our dataset on LSO neurons with Felmy’s dataset on another auditory brainstem nucleus (the INLL) for joint comparison and assessment within a meta-analysis. In summary, by correlating genome-wide expression profiles with the functional phenotype at single-cell resolution, our project will contribute substantially to a more comprehensive understanding of the functional organization of the central auditory system.

• DFG Programme: Research Grants