Effects of differential early social experience on biological and behavioral development in rhesus monkeys
- 作者：Suomi ; Stephen J.
- 刊名：European Neuropsychopharmacology
- 出版年：1996
- 期刊代码：95_0924977x
- 类别：med
- 出版时间：September, 1996
- 卷：6
- 期：Supplement 4
- 页码：S4/52
- 文件大小：127 K
摘要
Recent investigations of biobehavioral development have focused on short- and long-term consequences of different early social attachment relationships for rhesus monkeys raised in otherwise comparable physical and social settings. In these studies rhesus monkey infants were separated from their biological mothers at birth and were hand-reared in the laboratory for their first 6 months of life. At 30 days of age they were placed into social groups containing 3 other nursery-reared monkeys of comparable age; they remained in these peer groups until 6 months of age; control monkeys remained with their biological mothers throughout their first 6 months. After a series of short-term separations and reunions both the mother-reared and peer-reared monkeys were placed into larger social groups containing youngsters from both rearing conditions, among with an aged male-female pair (“foster grandparents”) where they were maintained until early adulthood. Thus, after 6 months of age the monkeys lived in the same physical and social environment. Analyses of behavioral and physiological data collected during the first 6 months of life revealed numerous significant differences in blood chemistry, activity profiles, and adrenocortical, neurochemical, and behavioral responses to brief separation between mother-reared and peer-reared monkeys, although both groups essentially demonstrated species-normative patterns of physical, behavioral, and physiological development. When the mother-reared and peer-reared monkeys were moved into common social groups after 6 months of age, most of the rearing condition differences diminished or even disappeared as long as the monkeys remained in their familiar social groups. However, when these monkeys were subsequently challenged by brief separation from their group, peer-reared monkeys consistently displayed more extreme behavioral disruption and physical arousal, as indexed by differences in plasma cortisol and ACTH levels and in cerebrospinal fluid concentrations of norepinephrine and serotonin metabolites. Moreover, when these monkeys were placed into new social groups, peer-reared monkeys displayed less affiliative behavior, more spontaneous and reactive aggression, and were less likely to attain high dominance status than their mother-reared counterparts. In addition, peer-reared adolescent monkeys consumed greater amounts of a sweetened 7%alcohol solution under ad lib conditions than their mother-reared cage mates. Finally, as young adults, peer-reared females were more likely to show inadequate maternal behavior toward first-born offspring, while peer-reared males were more likely to be expelled from their social group than their mother-reared cage mates. These results indicate that while long-term behavioral and physiological differences between peer-reared and mother-reared rhesus monkeys tend to be minimal when the subjects are maintained in stable, benign physical and social settings, exposure to environmental novelty and/or challenge continues to elicit differential behavioral and physiological reactions well into adulthood.