The mouse light-dark paradigm: A review

1 The light/dark paradigm is based on the innate aversion of rodents to bri ghtly illuminated areas and on the spontaneous exploratory behaviour of the animals, applying mild stressors i.e. novel environment and light. The tes t apparatus consists of a small dark secure compartment tone third) and a l arge illuminated aversive compartment (two thirds). 2 The test was developed with male mice. The strain, weight and age may be crucial factors. 3 The extent to which an anxiolytic compound can facilitate the exploratory activity depends on the baseline level in the control group. Differences b etween the type and severity of external stressors might account for variab le results reported by different laboratories. 4 In conclusion, the black and white test may be useful to predict anxiolyt ic-like or anxiogenic-like activity in mice. Transitions have been reported to be an index of activity-exploration because of habituation over time an d the time spent in each compartment to be a reflection of aversion. Classi c anxiolytics (benzodiazepines) as well as the newer anxiolytic-like compou nds (e.g. serotonergic drugs) can be detected using this paradigm. It has t he advantages of being quick and easy to use, without requiring the prior t raining of animals.