Influence of circadian factors on behavioral and cognitive testing in mice

In mice, behavioral responses are related to their circadian activity, which is regulated by the light:dark cycle, with their activity phase during the dark phase. Time of the day has been demonstrated to cause high variability in various behavioral measurements.

The present study aimed at investigating the influence of circadian factors as potentially confounding methodological factor on behavioral and cognitive testing in mice. -The results show significant differences in various behavioral parameters related to anxiety, exploration and locomotion, depending on whether the animals were tested during their activity or during their resting phase. However, different inbred strains were differentially affected by the illumination level during testing, probably due to their strain-specific behavioral characteristics. From our findings, we conclude that for the investigation of behavioral and cognitive performance in mice it is of fundamental importance to define stable testing conditions regarding time of testing within the circadian rhythm.