Representation and transformation of temporally complex odours in the mouse olfactory bulb
1 University of Bonn
The temporal structure of odour stimuli contain information about the environment that can be used to perform ethologically relevant tasks such as source separation and localisation. While there is a large body of literature on how invertebrates process and utilise temporal features, an equivalent understanding of mammalian neural correlates of temporally complex odours (TCOs) is lacking. We here investigate how TCOs are represented and transformed across the olfactory system, focusing on the olfactory bulb (OB). The OB is the first centre of odour processing with an extensive interneuron circuitry being a potential computational resource to extract temporal information from dynamic odour information. As the first step, we use OMP-GCaMP3 x Tbet-Cre transgenic mice expressing GCaMP3 in olfactory sensory neurons and Cre recombinase in mitral and tufted cells. Cre-dependent expression of jRGECO1a in projection neurons via stereotaxic viral injections, combined with dual-colour volumetric 2-photon Ca2+ imaging, allows us to simultaneously acquire both input and output signals from the OB. Coupled with a high-speed odour delivery device we then probe the neural correlates of isolated temporal odour features such as intermittency or onset latency and even present naturalistic odour plumes to explore the feature space of TCOs. The second part of the project involves extracellular recordings from projection neurons during targeted opto- or chemogenetic manipulations of different OB interneuron populations (e.g. GABAergic and dopaminergic) using cre-driver lines. This will allow us to understand local circuit mechanisms involved in encoding and modulating TCO information in the mouse OB.