Emotional trauma in rats: Age as a factor in recovery

Old (7 months of age) and young (2 months) male rats were divided into groups matched for spontaneous exploratory activity and for age. Experimental rats in the two age categories were then traumatized by giving them a 90 volt shock to the feet for two sec. on only one occasion. It was shown that nearly all the young rats recovered from the trauma within 5 weeks, as measured by brief exploratory activity and defecation, while at the end of 6 months the old rats still had not recovered. These results point up the greater resiliency of young animals, and the need for caution in the interpreting of research and theories on early experience.