Expression of c-Fos in the main olfactory bulb of neonatal rabbits in response to garlic as a novel and conditioned odour

Expression of c-Fos was examined in the olfactory bulbs of 3-day-old rabbit s after they had been presented with the odour of garlic as a novel stimulu s, as a learned odour, or during conditioning, and this expression compared with baseline levels in non-stimulated controls. Exposure to garlic odour resulted in substantial and widespread increases in c-Fos expression in the olfactory bulbs of all animals. However, although conditioned pups showed a specific behavioural response to the learned garlic odour, neither the am ount nor pattern of c-Fos expression differed compared to pups exposed to g arlic as a novel odour. The odour-induced expression of c-Fos was not well localised, although there was a significant increase in the number of granu le cells expressing c-Fos in the ventrolateral region of the bulb. These re sults support previous reports that the response to odours in the olfactory bulb of new-born animals is not as spatially distinct as that in adults. N evertheless, the immature olfactory system of these young animals is clearl y capable of very specific odour learning. (C) 1999 Elsevier Science B.V. A ll rights reserved.