Simple behavioral assessment of mouse olfaction

Abstract

This unit presents two basic protocols that offer rapid assessments of anosmia (the absence of a sense of smell) in mice. The buried food test is used to check for the ability to smell volatile odors. The olfactory habituation/dishabituation test is used to test whether the animal can detect and differentiate different odors, including both nonsocial and social odors. A non-contact method of odor presentation, along with a general method for collecting urine samples, is given as an alternate protocol. The tests described in this unit only require simple equipment and can be adopted readily by most laboratories.

Figure 1

Olfactory habituation/dishabituation setup. For a slant-top cage lid (left), insert the applicator through the water bottle hole. For a flat-top cage lid (right), insert the applicator through a hole on the grid cage lid and use a small weigh boat to stabilize the applicator. In either case, always insert the wood end first through the hole. The depth of insertion is approximately 4 cm (Wrenn et al., 2004; Crawley et al., 2007).

Figure 2

Olfactory habituation/dishabituation setup as described in the Alternate Protocol. The grid bars of the stainless steel cage lid and a piece of wire mesh prevent the subject from contacting the odor stimulus. Illustration kindly contributed by Professor Michael Baum, Department of Biology, Boston University.

Figure 3

Olfactory habituation/dishabituation results from oxytocin (OT) null mutant (triangle), heterozygote (square), and wildtype (circle) littermate mice. Generation of OT mutant mice is described in (Young et al., 1996). Figure shown here is reprinted from (Crawley et al. 2007) with permission. N = 7 male and 10 female +/+, 14 male and 15 female +/−, 6 male and 9 female −/−. All genotypes displayed significant habituation and dishabituation to non-social and social odors.