Topographical and laminar localization of 2-deoxyglucose uptake in rat olfactory bulb induced by electrical stimulation of olfactory nerves

Abstract

Experiments were carried out to examine the topographical projection of the olfactory nerves to the olfactory bulb in the rat, using the Sokoloff [14C]2-deoxyglucose (2-DG) technique. Electrical stimulation of a medially located bundle of olfactory nerves produced a discrete zone of 2-DG uptake at the rostral pole of the bulb. Increasing stimulus strength yielded a slightly larger focus at this site. In contrast, electrical stimulation of laterally situated bundles of olfactory nerves resulted in a broad zone of activity extending along the lateral wall of the bulb, and increasing stimulus intensity produced a more extensive area of uptake. Laminar analyses provided information on the relation between activity in the glomerular layer, where the olfactory nerves terminate, and activity in deeper layers. The results support previous studies of the topographical projections of the olfactory nerves to the olfactory bulb. They also support the hypothesis that odor-induced 2-DG uptake in the olfactory bulb represents activation of groups of receptors in the olfactory epithelium whose axons terminate in activated glomerular regions in the olfactory bulb.