OBJECTIVETo develop a novel method for continuously assessing the spatio-temporal properties of locomotor activity of mice in an open field using a video-tracking system.

METHODSThe locomotor tracks in the open field were recorded by video camera within 22 h, and analyzed by AnalyPower1.1 system that we developed recently. Total distance, distances traveled in different zones and their ratios to total distance; total time,times spent in different zones and their ratios to total time were used as indicators to assess the properties of locomotor activity.

RESULTSIn free and wakeful state, the locomotor activity of mice presented obvious regional and temporal properties. Mice preferred to stay in home base (food and water zones), and frequently visited the peripheral zones but seldom the center zones within 22 h. On the other hand, mice were most active within the first 1 h, and then their activity obviously decreased. After their activity became stable, the mice showed the obvious circadian variation of the activity as they were more active in the night.

CONCLUSIONThe novel method we developed in this study can continuously assess the spatio-temporal properties of locomotor activity quantitatively and objectively.