Effects of Temperament and Adolescent Social Experiences on Adult Exploratory Behavior

Open Access
Cooperstein, Samantha Leigh
Area of Honors:
Biobehavioral Health
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Sonia Angele Cavigelli, Thesis Supervisor
  • Lori Anne Francis, Honors Advisor
  • Lori Anne Francis, Faculty Reader
  • Adolescence
  • Temperament
  • Social
  • Stress
  • Adulthood
  • Behavior
Background: The goal of this study is to examine the effects of adolescent social experiences on adult behavior. Peer social interactions are considered to be one of the most crucial components of adolescence because they can produce long-lasting positive or negative behavioral outcomes in adulthood. Several studies have used rodents to model social stress during adolescence because adolescent rodents share similar emotional and social behavior changes with adolescent humans. One of the most prevalent types of adverse social experiences used in rodent studies is social isolation, whereby a rodent is individually housed in the colony room or removed from the colony room altogether for a specified period of time. The current study looked to see if adverse social experiences during adolescence altered exploratory and/or social behavior in adulthood. In addition to examining adolescent social experiences, the current study also examined temperament as a possible factor. Temperament refers to individual differences in behavior due to genetic makeup and may account for inconsistency in adult behavior. We hypothesized that isolated rats and/or inherently inhibited individuals will most likely suffer from the most severe behavior and emotional deficits as adults. Methods: 53 male Sprague-Dawley rats were weaned from their mothers on post-natal day (PND) 22 and lived in groups of three same-sex siblings until PND 28. On PND 28, all males were randomly assigned to one of three adolescent social conditions—kin groups (KIN), individual housing (IND), or social reorganization groups (SRO). KIN rats were housed in trios of same-sex littermates (N = 18); IND rats were housed individually (N = 18); and SRO rats were housed in trios with unfamiliar non-littermate males (N = 17). Rats remained in the adolescent social conditions until PND 46, at which point they were returned to the original kin trios. Rats underwent an exploration arena test during pre-adolescence (PND 20), mid-adulthood (PND 60), and late adulthood (PND 85). A social challenge was conducted in late adulthood (PND 110). Results: In mid-adulthood (PND 60), neophobic rats in kin groups and individual housing exhibited higher locomotion compared to neophilic rats that experienced the same social conditions as adolescents. Conversely, neophilic rats that experienced novel social partners during adolescence moved more compared to neophobic rats that had experienced novel social partners during adolescence. Further into adulthood (PND 85), locomotion and inspection no longer significantly differed among rats that experienced different adolescent social conditions. There was a main effect of temperament, though, in which locomotion was greater in neophilic rats than neophobic rats at this later age. Later in adulthood (PND 110), aggression, submission, and inspection did not differ between neophobic and neophilic groups or the 3 adolescent social experience groups. Conclusion: Adolescent manipulations did not predict behavior based on temperament throughout adulthood, just at one time point. These findings show that individual traits may develop over time but tend to remain stable. The lack of significant differences in social behavior in adulthood suggests that any type of social stress experienced in adolescence may not have long-term detrimental behavioral consequences in adulthood.