Development of a One-Day Test of Olfactory Learning and Memory in Mice

Abstract

Heather Schellinck developed a simple and reliable test of olfactory learning and memory in mice using a Pavlovian conditioned odour preference task in which CD1 mice learned to discriminate between two odours after two daily 10-min trials with the CS+ odour (sugar reward) and two trials with the CS- odour (no sugar) over 4 days. Mice remembered the CS+ for up to 60-days after training in this study and, in other studies, male and female C57BL/6J and DBA/2J mice could remember the odour discrimination for up to 9-months after training. Mice up to 24-months of age can learn and remember the odour preferences. Likewise, the 5×FAD mouse model of Alzheimer disease showed no odour memory deficits in this task. In the present study we developed a 1-day training procedure in which male and female mice received eight CS+ and eight CS- odour presentations on 1 day and were then tested for memory 24-h, 7-days and 30-days later. Mice (C57BL/6J × SJL/J and C57BL/6J) given the 1-day training showed a conditioned odour preference on 24-h, and 7-day memory tests with no sex differences. After 30-days the odour preference was not significant. Mice (C57BL/6J) given four CS+ and four CS- trials showed no significant odour preference on 24-h and 7-day memory tests. The results suggest that different 1-day training paradigms result in different memory strength. Such a 1-day appetitive training test could be valuable for studying the neurobiological bases of short-, long-, and very long-term memory.