Adult development: plasticity of stable behavior.

Abstract

Gerbils in a longitudinal study demonstrated very stable behavior over more than a third of their median lifespan. There was highly significant individual stability of such behaviors as locomotor activity, rearing on the hind legs, latency to jump down from a platform, and marking with the ventral gland for thirteen months of adult life, from six to eighteen months of age. In some of these behaviors, general changes were observed over time, such as increased latency to jump down from a platform. Additionally, brief, outdoor enrichment (one hour a month) resulted in more scent marking than was found in control gerbils. In gerbils tested monthly there was less locomotor activity and rearing on the hind legs than in gerbils tested only once. It was observed that gerbils with a strong tendency to have seizures had more locomotor activity, more rearing, fewer markings, and shorter latency to jump down from a platform than those who rarely seized. Further, when gerbils had a seizure prior to testing, their activity scores and number of rearings were greater than on days when they did not have a seizure. Sex differences are discussed. These normative data provide important knowledge of adult development for comparison with studies of aging changes in gerbils.