Imaging Odor Coding and Synaptic Plasticity in the Mammalian Brain with a Genetically-Encoded Probe

MCGANN, J.P.; PÍREZ, N.; WACHOWIAK, M.

New York

Conferencia; 28th IEEE EMBS Annual International Conference; 2006

IEEE

We have used the genetically-encoded fluorescentexocytosis indicator synaptopHluorin (spH), expressedselectively in mouse olfactory receptor neurons, to image odorrepresentations at the input to the olfactory bulb. The olfactorybulb is a powerful system for in vivo fluorescence imagingbecause its inputs are segregated into receptor-specificfunctional units (glomeruli) that are optically accessible andreceive massively convergent input from sensory neurons. In aline of transgenic mice expressing spH under the control of areceptor neuron-specific promoter (OMP), odorant-evokedpatterns of receptor neuron input to ~ 10% of the olfactorybulb can be imaged with excellent spatial resolution andsensitivity during single brief odorant presentations. Odorrepresentations are similar across mice and can be imagedrepeatedly in the same animal for months. In olfactory bulbslices from OP-spH mice, shock-evoked spH signals are rapidand linear reporters of transmitter release, although controlfor changes in extracellular pH is critical for properinterpretation of the spH signals. These features have allowedus to characterize the functional organization and mechanismsof presynaptic modulation of transmitter release at the firstolfactory synapse. The capacity for long-term chronic imagingpermits the direct visualization of the function regenerationand remapping of input to the olfactory bulb after lesions ofthe nasal epithelium.