[Behavioral comparisons of rats (Rattus norvegicus) in Runway, open-field, and I-maze]

Behaviors of two strains of rats (F344/DuCrj and Wistar-Imamichi) in three novel situations (Runway, open-field, and I-maze) were compared in order to clarify the characteristics of each situation. Eighty rats were used; 40 were F344/DuCrj and 40 were Wistar-Imamichi. Principal component analysis of each ambulation score abstracted two major components of 'activity' and 'emotionality'. Highly 'active' rats ambulated much in the three situations, whereas highly 'emotional' rats ambulated much in the open-field test and little in the Runway test. These results suggest that there appeared 'escape response' in the open-field test, while 'freezing response' occurred in the same rat in the Runway test. Wistar-Imamichi was more 'active' than F344/DuCrj, whereas the latter was more 'emotional' than the former. This study also confirmed the idea that the rats were frightened in I-maze less than in Runway.