The effects of early experience on the hippocampus.

Abstract

Some experiences occurring early in life affect structure and function of the nervous system. Handling and isolation of infant rats produce physiological and behavioral changes that persist throughout life. These changes may result from interference with the maturation of late developing systems, such as the hippocampus. The research reported here used handling and isolation alone, and in combination, and measured activity, cognitive ability and plasma CORT levels in adult rats. Handling resulted in increased activity, decreased CORT levels, and impaired spatial learning ability. Isolation failed to alter activity levels, impaired spatial ability, and increased CORT levels in females, and reduced them in males. Combining the two manipulations produced no changes in behavior or CORT levels. The results are discussed in terms of altering the manner in which the animals respond to environmental challenges.