Materials and Reagents

1. Filter paper (Bio-Rad Laboratories, catalog number: 1703967 )
   
2. Pipet or syringe (BD, catalog number: 309625 )
   
3. Low odor epoxy or glue, or tape to seal the scent cup
   
4. Adult 3-8 months old mice, for the testing group (transgenic NR2A overexpression mice) and wild type mice for the control group (referred to as “subject mouse”)
   
5. 70% ethanol solution
   
6. Fresh or canned, non-expired 100% juice samples [pineapple (Dole), orange (Tropicana), 100% lemon and 100% lime juices] (see Figure 1)
   

Equipment

1. Clean mouse cages identical to the home cage (7.5 in x 11 in x 5 in), one for each subject mouse per phase
   
2. Clear Plexiglas to cover the cage top (so the mice cannot climb out)
   
3. Small plastic container with a lid (i.e., a plastic petri dish, 35 mm x 10 mm) (Thermo Fisher Scientific, catalog number: FB0875711YZ , or other similar replacement)
   
4. Drill with small (1 mm) drill bit or 18 g needle (BD, catalog number: 305196 ) for making holes in top of scent cup
   
5. Digital recording camera
   
6. Laboratory timer
   
7. Stopwatch for recording investigation times
   
   
   Figure 1. Experimental set-up for the olfactory recognition task. For the olfactory recognition task, a selection of juices (pineapple, orange, lemon and lime), a small Petri dish, a syringe and an empty clean mouse cage are used.
   

Procedure