The proposed project aims at a better understanding of early olfactory processing, in which the large dendrodendritic reciprocal synapse between mitral cells and granule cells is a main player. Our approach will be based on simultaneous application of two-photon imaging of calcium dynamics and conventional electrophysiology of synaptic transmission in vitro. Given a long-term goal of understanding the nature of processing of olfactory information in the bulb at a systemic level, the following lines of research are proposed: Having investigated the calcium dynamics following stimulation of the mitral cell-granule cell synapse, we will measure the influence of the emotion- and arousal-related neuromodulator norepinephrine on calcium transients and synaptic transmission in this synapse, since there are strong neuromodulatory projections into the olfactory bulb. Finally, we plan to investigate transmission at the mitral cell-granule cell reciprocal synapse in the context of a more intact circuit, in order to further elucidate the influence of centrifugal inputs on signal processing in the olfactory bulb. To do so, we will develop an integrative slice preparation containing also extrabulbar elements, i.e. part of the olfactory cortex.
