SYNAPTIC TRANSMISSION IN THE OLFACTORY BULB

Florida State University, Tallahassee FL

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Abstract

DESCRIPTION (adapted from applicant's abstract): Odor information processing by the olfactory bulb (OB) is dependent on the properties of olfactory synaptic circuits. Most excitatory synapses in the OB use glutamate as a transmitter, including olfactory sensory neuron-to-olfactory bulb neuron synapses and mitral/tufted cell-to-interneuron synapses. Although it is known that the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)/kainite subtypes of glutamate receptors play important roles at these synapses, it is not known whether AMPA receptors, kainate receptors, or both are involved or if these receptors are presynaptic as well as postsynaptic. It is also not known which OB neurons express which receptor subtypes nor the functional or neuromodulatory properties of these subtypes. Because AMPA/kainate receptors are ion channels formed from multiple subunits, subunit diversity strongly influences the kinetics and neuromodulatory properties of the receptor, and consequently, the behavior of synaptic circuits involved in odor processing. The specific aims of this project are: 1) To determine the pattern of expression of AMPA/kainate glutamate receptor subunits among olfactory bulb neurons; 2) To determine the functional diversity of AMPA/kainate receptors on olfactory bulb neurons; and 3) To determine the properties of synaptically activated AMPA/kainate receptors. The experimental approach includes immunocytochemistry, and patch-clamp electrophysiology in both primary culture and olfactory bulb slices. These experiments should provide a greater understanding of odor information processing by the olfactory bulb and provide clues to the myriad of neuropathological conditions that affect olfactory function.