Spatio-temporal analysis of locomotion in BALB/cByJ and C57BL/6J mice in different environmental conditions.

We analysed spatial and temporal characteristics of mouse locomotion and investigated whether mouse gait differed between strains and environments. To this end, we used two inbred strains of mice (BALB/cByJ and C57BL/6J) known for their contrasting inherent level of anxiety, in three different visual surroundings. The animal position was determined relative to each environment. Gait cycle, defined as the sequence of limb movements, was analysed relative to time. We also recorded spatial parameters of gait such as stride length, track width and footfall characteristics. These measures allowed us to obtain an accurate description of locomotion and to assess subtle modifications of the gait. We found that mice adjusted their position in space, posture and gait in order to either stabilize their body on the ground in a potentially unsafe environment, or to optimize propulsion and maneuverability in a safer location. In addition, the two strains of mice used different strategies, suggesting that the inherent level of emotionality may affect the organization of locomotion in mice. We further concluded that higher structures of the central nervous system are involved in the online control of locomotion.