Receptive fields of second-order neurons in the olfactory bulb of the hamster.

Abstract

Electrical stimulation of nerve fibers emerging from different positions of the olfactory epithelium was used to determine the receptive fields for 52 olfactory bulb neurons in the hamster. The responses of olfactory bulb neurons were recorded extracellularly with metal-filled micropipettes. Suprathreshold stimuli (500 .mu.A) were applied to each of 8 standard epithelial positions spaced .apprx. 250 .mu.m apart, and the position, or positions, which, when stimulated, produced a response in the bulb were taken as an index of the neuron''s receptive field. Most bulb neurons have very localized receptive fields limited to only 1 or 2 stimulating positions. There was a statistically significant correlation between the location of a neuron''s receptive field in the olfactory epithelium and the recording depth of the neuron in the olfactory bulb. In the mammalian olfactory system there exists a topographical projection of input from localized regions in the epithelium onto the 2nd-order neurons in the olfactory bulb.