Factors controlling measures of anxiety and responses to novelty in the mouse.

This review focuses on factors influencing behaviour in the elevated plus-maze, the holeboard and the social transmission of food preference. The elevated plus-maze provides independent measures of anxiety (percentage of time spent on open arms) and activity (number of closed arm entries) and can be used in both males and females. Important sex differences emerge in factor loadings, and, whereas in males, anxiety is the primary factor, in females it is activity. On trial 2 in the plus-maze, the nature of the anxiety state is changed and thus this maze can be used to screen for possible genetic alterations in two distinct anxiety states. The holeboard provides independent measures of exploration and locomotor activity and habituation between sessions provides a useful measure of learning. Mice display neophobia and avoid novel foods, but information about their safety can be socially transmitted. A mouse that has sampled a novel food will be actively sniffed by others on its return to the colony. It is important to control for possible changes in social investigation, neophobia, olfactory sensitivity, anxiety and exploration, before it is concluded that a changed performance in this task is due to changes in learning.