Age has a strong influence on our behavior. Just look around the next time you are at the grocery store: a toddler is flailing on the ground in a temper tantrum; a young girl spins fervently in circles while waiting with her mother in line; an old woman slowly inches her way down the aisles, pausing for long periods to choose each item. While some of these behavioral differences may be due to socialization and the lifetime of governing influences on our behavior, there are also innate biological changes in behavior with aging due to changes in brain function.

Such changes in humans are mirrored in the behavior of our laboratory mice. Many of us have had the experience of opening a cage of weanling mice, only to have one vault from the cage as if on springs. I have spent many an afternoon crawling around on the vivarium floor, trying to retrieve a vital study participant. We’ve also witnessed the aging of our mice; like humans, they become fatter, their activity begins to slow, and, if the timing of our experiments allows, we see their hair begin to gray.