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Rainer Friedrich

Wednesday 20th January 2016

Time: 4.00pm

 

Ground Floor Seminar Room

25 Howland Street, London, W1T 4JG

 

Deconstruction and reconstruction of neuronal computations in olfaction

 

Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland

We use the olfactory system of zebrafish as a model to understand neuronal computations involved in pattern classification. Exploiting the small size of the zebrafish brain, we measure neuronal activity patterns using multiphoton calcium imaging, manipulate neuronal activity using optogenetics, and reconstruct neuronal circuits using serial block face scanning electron microscopy (SBEM). In the olfactory bulb, we found that distributed odor-evoked activity patterns are stabilized against variations in intensity by a neuronal circuit that amplifies weak input but attenuates strong input through gap junctions and GABAergic synapses, respectively. In addition, we found that overlapping input patterns representing similar odors are actively decorrelated. These two computations are likely to represent important functions of the olfactory bulb in a pattern classification process. In order to obtain deeper insights into the underlying mechanisms, we developed new methods for SBEM and densely reconstructed the neurons in the olfactory bulb of a zebrafish larva. We found that long-range inter-glomerular projections in the olfactory bulb are not random but organized by the identity of olfactory glomeruli. Preliminary results indicate that this non-random circuit organization contributes to neuronal computations involved in olfactory pattern classification.