Mechanisms of processing temporally structured olfactory stimuli

• Applicant: Professor Dr. Tobias Ackels
• Subject Area: Cognitive, Systems and Behavioural Neurobiology ; Molecular Biology and Physiology of Neurons and Glial Cells
• Term: from 2015 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 280511863

An odorant plume harbours a mixture of different odours constantly intermingled by air turbulences. Odour intensity fluctuates depending on the distance of an odour source, odours emerging from the same source (such as, say, the different chemicals that make up the smell of a flower) share a common temporal structure in their intensity variations. Thus, analysing the temporal properties of an odour stimulus might provide key information for an animal to locate and discern different odour sources. In this project, I propose to combine behavioural, physiological and optogenetic experiments in mice to assess how such temporally modulated odours are represented and discriminated.To isolate odour quality and intensity, sensory input from the nose is conveyed to the olfactory bulb where it is processed by the local neural circuitry. Granule cells comprise the most numerous type of interneurons in the olfactory bulb. They have been shown to play an important role in shaping temporal activity, including the precise, coordinated firing of projection neurons. Furthermore, their long dendrites allow for widespread signal integration over the entire bulb. Together, this renders them an excellent candidate for shaping the representation of temporally structured odour stimuli.The major goal of this new study is to elucidate the role of granule cells by employing an olfactory task where stimuli will be presented in a complex temporal structure. I will assess the influence of inhibitory granule cells on behavioural performance and stimulus representation using intracellular recordings from identified projection neurons in awake, behaving head-fixed mice. I will determine the bandwidth of odour discrimination for both temporally structured individual odours and odour mixtures. Acute interference in granule cell activity using optogenetic silencing will let me investigate the impact of granule cells on discriminating temporally structured odours. In vivo physiological recordings from projection neurons in awake, behaving head-fixed mice with silenced granule cell activity will provide direct information about the influence of the granule cell circuit on olfactory bulb neural output.The expertise of Prof. Andreas Schaefer and his lab, the state-of-the-art experimental techniques they have established and the scientific environment at the Division of Neurophysiology at the National Institute for Medical Research, the Francis Crick Institute and University College London, all provide an excellent surrounding to successfully conduct this new study.

• DFG Programme: Research Fellowships
• International Connection: United Kingdom
• Host: Professor Dr. Andreas T. Schaefer