Open-field social behavior in rats as a function of septal lesions in infancy and group versus isolated rearing conditions

Abstract

Normal rat pups and pups with septallesions produced at 7 days of age were reared after weaning under group and isolated housing conditions. Contact time between pairs of animals in the open fieldwas observed at 90·110days of age. Gregariousness was increased by both septaliesion treatment and isolated rearing conditions. The housing condition variable accounted for a greater proportion of treatment variance than did the lesion variable. These results stress the importance of housing conditions as a confounding variable in studies of recovery from infant brain damage.Jonason and Enloe (1971) reported a dramatic increase in open-field gregariousness of the rat following lesions of the septal forebrain. Johnson's (1972) studies indicated that the enhancement of gregariousness effect can be observed regardless of the age at the time the lesion was produced. Meyer, Ruth, and Lavond (1978) demonstrated that the impact of septal lesions on social contact in the rat is potent and lasting, A body of evidence has been produced primarily by Latane and his colleagues (Latane, Nesbitt, Ekman, & Roden, 1972) that isolated vs. social housing conditions is also a potent variable in the openfield gregariousness of rats. The Latane studies indicate that adult rats housed in isolation are more gregarious in the open field than are animals reared in group cages.In the Johnson (1972) experiment, following septal lesions, animals were housed individually from 45 days of age until open-field observations on adult animals were completed. It is possible that the isolated housing conditions might have confounded the data relevant to the lesion variable in that study. In order to more clearly view potential recovery of function following septal lesions, we need more Information on how septal lesions in infancy and housing conditions during development interact.The current study was designed to evaluate the interaction of housing conditions during development and septal lesions in infancy. METHonDellln, SubJeetl, .nd Rou1lnlEach litter was culled to eight male pups at 5 days of age. At 7 days of age, 48 pairs of animals were assigned to four groups (12 The authors' mailing address is:

Effects of septal lesions on open-field gregariousness in rats reared prior to surgery in group versus individual cages

“…In summary, current and previous studies (e.g., Johnson et al, 1984) demonstrate that housing density during development can have a potent impact on the effects of open-field behaviors following septal lesions. This is observed in both hooded and albino rats, and is found whether surgery is performed in infancy or in adulthood.…”

“…In a previous study (Johnson et al, 1984), we reported that open-field contact following septal lesions in infant hooded rats could be modified by the type of postweanIing housing maintained until observation. The present study demonstrates essentially the same pattern of results in albino rats when septal lesions are produced in adult animals following a developmental history of differential housing.…”

“…Animal behavior studies have also demonstrated that when animals are housed in isolation for several weeks prior to observation in the open field, contact times are increased (e.g., Latane, Nesbitt, Eckman, & Rodin, 1972). In a recent study (Johnson, Spiker, & Carlson, 1984), we investigated whether isolated versus group housing during development might interact with septal lesions produced in infancy. Results from this study indicated that both septal lesions and isolated housing produced increases in social contact time.…”

“…In the prior study (Johnson et al, 1984), housing conditions and septal lesion were both developmental variables. The present study looks at contact time following septal lesions at 90 days of age in rats reared with either group or isolated housing histories since weaning.…”

The effects of septal lesion on the open-field social behavior of Sprague-Dawley albino rats

“…Previous studies in our laboratory (Johnson, Spiker & Carlson, 1984;Poplawsky & Johnson, 1973) as well as a number of studies at Ohio State (Jonason & Enloe, 1971;Meyer, Ruth, & Lavond, 1978), have demonstrated that lesions of the septal forebrain in Long-Evans hooded rats result in a marked increase in open-field gregariousness (contact time). Increased contact time has also been observed in adult animals following septal lesions produced in 7-day-old infant Long-Evans rats (Johnson , 1972).…”