Lesley A. Syme

Social isolation at weaning: Some effects on two measures of activity*

Both the age at which housing conditions are imposed and the type of activity measured are shown to affect the results obtained in studies concerned with the effects of social density on the behavior of laboratory rats.

The role of social isolation and sex in determining effects of chlordiazepoxide and methylphenidate on exploratory behaviour

Effects of two doses each of chlordiazepoxide and methylphenidate on exploration, locomotion and rearing were observed in isolated and grouped male and female rats. Sex of the animals determined the effects of both drugs on rearing, and of chlordiazepoxide on preferences for the novel half of an exploration box. Drug administration seemed to abolish initial sex differences on the former response. Locomotion of isolated and grouped animals was also differentially affected by chlordiazepoxide. These findings emphasised the need to take genetic and environmental factors into account when considering the effects of psychotropic drugs on exploratory behaviour.

An analysis of the limited access measure of social dominance in rats

Abstract The limited access situation in which only one of two or more subjects can gain access to a reward during a restricted time-period is an accepted measure of dominance in the rat. This study attempts to validate the technique by establishing the relationship between individual and competitive performance in order to determine whether ‘priority of access’ has been measured. The generality of the competitive orders is examined by altering the competitive response while retaining the same reward. In view of the data collected for both time and weight-gain measures in food and water competition it is doubtful whether the limited access competitive technique can be considered a valid measure of dominance for the laboratory rat.

Spatial distribution and social status in a small herd of dairy cows

Abstract Observations were made of the positions of seven dairy cows within a familiar square arena over ten consecutive days using overhead time-sample photography. A linear aggressive order was also determined at pasture and during supplementary feeding. While the data support an inverse relationship between social status and spatial proximity, animals lower in the aggressive order did not show any marked avoidance of more dominant cows. In contrast to some theories one paired association occurred between cows adjacent on the order, where aggressive behaviour might be expected. Whereas the highest ranked cow snowed little movement between observations, there was a high correlation between social rank and movement in the other animals.

The role of sex and novelty in determining the social response to lithium chloride

Effects of lithium chloride on the social behaviour of male and female rats were measured in unfamiliar and familiar test situations using a photographic technique. Lithium-treated females showed an increase in body contact and a decrease in social distances in comparison with saline-treated controls in both test conditions. Males administered lithium showed increased corner occupancies in the novel test setting while in the familiar test they showed decreased body contact and increased average group social distance in comparison with the saline condition. Further tests in an exploration box confirmed that lithium decreased the general environmental responsiveness of male rats. The results are discussed with reference to the anti-aggressive effect of lithium.

Effects of chlorpromazine and methamphetamine on sociability in rats

Using a time-sample photographic method three measures of sociability showed, contrary to some previous findings, rats administered chlorpromazine (3 mg/kg) to be more sociable than those treated with methamphetamine (2 mg/kg) or isotonic saline. Saline animals were more sociable than amphetamine-treated subjects on two measures. This illustrative study demonstrates that variables influencing sociability results may include social conditions in the cage, post-injection and test environments, and the measure employed.

Effects of lithium chloride on the activity of rats tested alone or in pairs

Group-housed rats, injected with an acute dosage of 3 meq/kg lithium chloride, were tested on an activity platform either alone or in pairs 20 min or 3 h after drug administration. Contrary to previous findings, rats administered lithium were less active than those treated with saline after both post-injection periods. However the activity of the saline control animals tested alone after 3 h was considerably less than that exhibited by the same group after 20 min. This activity difference, which could be interpreted as a lithium-social or lithium-time interaction, is more simply explained in terms of the effects of the social isolation occuring between drug administration and testing.

Group instability and the social response to methamphetamine

Abstract The effects of methamphetamine on body contact and social distances in stable (familiar) and unstable (unfamiliar) groups of rats were investigated. Although there was no difference in body contact in the stable and unstable saline groups, methamphetamine reduced body contact significantly more in the unstable group than it did for its stable counterpart. Methamphetamine had no effect on social distance in the unstable group but decreased social distance in the stable group. Group stability may therefore be not only desirable but necessary, if the effects of drugs on social responses are to be meaningfully interpreted.

EVIDENCE FOR CAGEMATE PREFERENCE IN THE LABORATORY RAT

3 illustrative studies using a time-sample photographic method for the measurement of sociability and social preference in rats showed that, in contrast to previous findings, rats prefer cagemates over strangers when placed in a novel environment. An alternative analysis of social distances is discussed.

Social Inhibition of Locomotor Activity in Mice

Male mice engaged in less locomotion in an open field when in the company of another male mouse than when alone. This social inhibition of activity contrasts with the previous finding that rats tested in pairs showed an increase in activity. The significance of these findings for the interpretation of general activity of mice within the open field is discussed.