Novelty affects paw preference performance in adult mice

The hemispheres are asymmetrically involved in the reaction to stressful situations. In this sense, it is possible to speculate that the asymmetrical activation of the hemispheres, as a result of the exposure to a novel situation, may affect behavioural lateralization. We tested the hypothesis that novelty affects performance in a paw preference task in 37 habituated (HAB) and 37 control (CT) adult male Swiss mice. For 4 days prior to the first testing session, HAB mice were placed in the testing box daily. After the fourth session, animals were deprived of food for 24 h. On the 5th day, food pellets were placed inside a feeding tube and animals were allowed to make 25 successful retrievals of food pellets. The testing procedure was repeated 4 days later. CT mice were not submitted to the habituation sessions. A significant side-dependent difference in consistency of laterality was observed between groups in the first session: all (100%) right-pawed CT mice used their right paw to make their first successful retrieval of food in the first testing session, while only 61% of left-pawed mice used their left paw. The same pattern was observed when the first five retrievals were considered: 100% right-pawed CT mice and 72% left-pawed CT mice were consistent. No differences were observed in the HAB group: in both side-preference subgroups, 88% of the animals showed consistent laterality. These results indicate that behavioural lateralization in paw preference is affected by the novelty of the testing situation in a side-dependent manner.