Brief periods of socialization and later behavior in the rat

Abstract

Juvenile rats were allowed short daily periods of social contact to see if this would reduce the known effects of isolation rearing upon habituation of locomotor activity and object contact in the open field. Animals totally deprived of social experience (ISOL) were slower to habituate than animals living in small social groups (SOC). Rats allowed 1 hr of social contact (partial isolates, PI), but living otherwise in isolation, were intermediate between ISOL and SOC animals. In further experiments the quality of social interactions in the daily period was altered by drugging one of the partners, either with amphetamine or with chlorpormazine. In later tests in the open field, the rats that had interacted with amphetamine-injected or chlorpromazine-injected partners differed from PI animals in the direction of resembling complete isolates (ISOL); this was particularly true of those paired with amphetamine animals. Observation revealed that injection of 1 of the partners considerably altered social interactions in the pair. A further test showed that 1 hr of contact a day considerably alleviated the deleterious effects of isolation rearing upon response reversal. We conclude that normal development in the rat may depend upon the flexibility of behavior encouraged by the early social situation.Recent reports (Rosenzweig, 1971; suggest that some of the behavioral effects of keeping rats in impoverished conditions may be caused by social isolation prior to 50 days of age. One such behavior is the slow reversal of a previously learned discrimination. Rosenzweig found that rats that were isolated for 30 days from 25 days of age were slow to reverse a previously learned visual discrimination, but that reversal was not affected if isolation occurred after 60 days of age. Furthermore, he has reported that although environmental enrichment of social rats affected brain development it did not affect reversal, suggesting that it is specifically social factors that are implicated in t h s deficit. Similarly, we have found that hyperactivity and habituation deficits which are found following early isolation cannot be produced by isolation initiated after 45 days of age, nor can they be reversed in rats isolated between 25 and 45 days of age by subsequent housing in social groups for up to 90 days in press).

Early play may predict later dominance relationships in yellow-bellied marmots (Marmota flaviventris)

“…Indeed, not only are hypotheses non-mutually exclusive, play may have different functions at different parts of an animal's life [8]. A fundamental and ethical challenge in studying play is that it is difficult to deprive animals only of play (but see [10,11]) and that deprivation of play typically impedes normal development [12,13]. Thus, we must often accept correlative support for hypotheses.…”

Social reward-conditioned place preference: A model revealing an interaction between cocaine and social context rewards in rats

“…Social play in adolescent rats is thought to serve an essential role in fostering healthy development (Einon et al, 1978;Meaney & Stewart, 1979;Van den Berg, Hol, et al, 1999;Vanderschuren et al, 1997). Numerous studies suggest that nature has imbued the opportunity to engage in social play with intrinsic natural reward.…”

Play fighting versus serious fighting in golden hamsters (Mesocricetus auratus)

“…In rats, it has also been observed that even a short period of isolation increases the frequenc y of play fighting (Panksepp , 1981;Thor & Holloway , 1984). The locomotor hyperactivity , previously demonstrated in isolated rats (Einon, Morgan , & Kibbler , 1978), could also account for these results-greater locomotion would bring these animals into contact more frequently, resulting in a higber rate of play fighting. In accordance with Scott's (1966) and Einon & Morgan's (1977) suggestions, isolation during critical periods of socialization seems to have significant and lasting effects on aggression .…”