Abstract
Olfactory memory is an ethologically relevant task that relies on a mouse’s innate ability to use olfaction to forage for food (Zou et al., 2015), and identify safe foods. Although many of the same brain areas involved in other forms of memory are also involved in olfactory memory, the mechanisms are different (Sanchez-Andrade et al., 2005; Tong et al., 2014). Here, we describe one way to test olfactory memory in mice. The protocol described can be used to test long-term memory (memory which requires de novo protein synthesis) or short term memory by adjusting the delay time between the training session and the recall session (Freedman et al., 2013) and has been designed to mimic the single presentation of the social recognition paradigm. This paradigm relies on the mouse’s innate tendency to investigate a novel scent more than a familiar scent. Transgenic NR2A overexpression mice are known to have impaired long-term olfactory memory, but intact short-term memory, and are used here to demonstrate how one form of impaired olfactory memory may appear. Other genetically or chemically manipulated mice may be used in place of the transgenic mice used here.
Materials and Reagents
Equipment
Procedure
Representative data
Figure 3 is representative data for a 24-h olfactory recognition memory task. In this task, the mice were introduced to a fruit scent in the first round and were allowed to investigate the fruit scent for 5 min. The mice were then split into two groups; one group will be presented with the identical scent, the other group will be presented with a novel scent. The wild type mice are able to learn and recall the familiar scent, as evident by the significant decrease (as determined by a Student’s t-test) in the exploration of the familiar scent in the recall phase. The NR2A mice (used here to demonstrate impaired olfactory memory) are unable to recall the familiar scent in the 24 h recall phase and did not significantly reduce the exploration times of the familiar scent. Figure 3. Representative data for a 24 h long-term olfactory recognition task. A. Representative exploration times, in seconds, of the juice for both the wild type and the NR2A transgenic mice. The identical scent was used in both sessions. B. Graphical representation of the averages of the exploration times. C. Representative exploration times, in seconds, of the juices for both the wild type and the NR2A transgenic mice. A novel juice was presented in the recall session. D. Graphical representation of the averages of the exploration times with. A novel juice scent was presented in the recall session.
Notes
Acknowledgments
This work was supported by funds from the National Institute of Mental Health (MH060236), National Institute on Aging (AG024022, AG034663 & AG025918), USAMRA00002, and Georgia Research Alliance (all to JZT). This protocol was adapted from (Jacobs and Tsien, 2014; Jacobs et al., 2015).
References
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