Temporal structures of open-field behavior of the high- and low-activity mouse strains: comparison with ICR and five inbred strains of mice

Abstract

The present study examined open-field behavior in the high- and low-activity mouse strains, ICR, and five inbred strains of mice (BALB/c, C3H/He, CBA/Ca, C57BL/6, and DBA/2). The high- and low-activity strains were characterized as the highest and the lowest in ambulatory activity, respectively. However, they did not differ for defecation. A principal component analysis applied to observational data based on 11 behavioral items revealed four components, which accounted for 64% of the total variance. The strain differences found in component 1 and 2 could be described from four elements (initial values, changes in 1-3min and 4-10min of the test period, and final values). The high-activity strain contrasted with the low-activity strain in component 1, whereas they resembled each other in component 2. The similar pattern of strain differences was also found between BALB and C57BL. Component 2 might be related to a trait independent of “activity” or “emotionality”. Open-field behavior of the high-activity strain was much more similar to that of ICR (a base population of the selection) than the low-activity strain, which indicated that genetic changes had occurred mainly in the low-activity strain.