Can olfactory bulbectomized rats detect odors?

Neonatal (P2) rats received a unilateral olfactory bulbectomy and were later trained in an olfactometer to detect ethyl acetate and chocolate chip cookie odor. After removal of the remaining olfactory bulb, rats were tested for retention and trained to detect cineole, gardenia perfume and amyl acetate. Rats with an intact olfactory bulb served as controls. Anterograde transport of horseradish peroxidase applied to the olfactory epithelium was used to assess forebrain projections of sensory neurons. Four experimental rats with connections from the olfactory epithelium to the olfactory peduncle or olfactory cortex performed about as well as controls on odor detection tasks. Olfactory connections of the remaining seven rats appeared to be restricted to frontal cortex, and these rats were anosmic. Results indicate that, in the absence of the olfactory bulbs, projections from olfactory epithelium, to olfactory peduncle or to olfactory cortex can support detection of vapor stimuli.