Automated video analysis of age-related motor deficits in monkeys using EthoVision

Previous studies comparing age-related changes in locomotor function in nonhuman primates have generally relied on subjective human observations or rudimentary infrared motion sensors. Here, we used the automated video-tracking system EthoVision to objectively quantify locomotor activity in 6 young, 6 middle-aged and 12 aged female rhesus monkeys. The video records were analyzed for distance traveled, movement speed and vertical activity. Our results showed that the young monkeys (4.9 +/- 0.1 years old) traveled twice the distance and moved 48% faster than the middle-aged monkeys (15.7 +/- 0.5 years old), and traveled thrice the distance and moved 67% faster than the aged monkeys (26.3 +/- 0.9 years old). In addition, young monkeys were vertically more active (20/60 min) than both the middle-aged (7/60 min) and the aged (1/60 min) monkeys. Furthermore, the locomotor performance of the individual animals significantly correlated with increasing age for all three measures. We conclude that EthoVision is a reliable and objective tracking method for detecting age-related differences in locomotor movements in rhesus macaques, and possibly in humans.