Exploratory activity and motor coordination in old versus middle-aged C57BL/6J mice.

Aged mice were compared to middle-aged mice in two tests of exploratory activity and two tests of motor coordination. The 16-month-old mice had more ambulatory and rearing movements than 24-month-old mice, but fewer stereotyped movements. In contrast, no difference was found in the emergence test. The 16-month-old group outperformed the 24-month-old group on the stationary beam and coat-hanger tests. Regression analyses indicate that the number of falls from the stationary beam was positively correlated with movement times (MTs) before reaching the end of the horizontal bar. However, there was no significant correlation between open-field measures and emergence latencies, indicating that the two tests of exploratory activity estimate separate aspects of behavior.