The enigma of olfactory learning revisited.

If, as indicated in olfactory conditioning studies, rats are able to demonstrate primate-like behavior by their acquisition of response strategies, rodent olfactory learning may provide a particularly useful model for neurobiological analyses of learning and memory. Reid and Morris [Proc. R. Soc. Lond., Ser. B 247, 137-143 (1992); Trends Neurosci. 16, 17-20 (1993)] have recently challenged these views. They suggested that the evidence for acquisition of an olfactory learning set in rodents is insufficient and that rat olfactory learning may provide no special advantage for the neurobiologist. This essay reviews the relevant studies and concludes that there are serious shortcomings in the Reid and Morris argument, that the available data base provides clear evidence for the claim that rats acquire abstract rules for responding and that olfactory learning may be qualitatively different from other forms of instrumental learning in rodents.