Neonatally bulbectomized rats with new olfactory-neocortical connections are anosmic

Rats with one olfactory bulb removed when neonates and the second bulb removed when adults were tested on tone-light discrimination and odor detection tasks. On the neonatally operated side reconstituted olfactory receptor cell axons penetrated the frontal neocortex or portions of the anterior olfactory nucleus, and formed glomerular-like structures. On the adult operated side there was extensive scar formation which prevented in-growing sensory axons from contacting the brain. All experimental animals acquired the tone-light discrimination but failed to show any evidence of odor detection. These results indicate that reconstituted olfactory projections which terminate in the frontal neocortex or anterior olfactory nucleus do not support olfaction.