The development of intersession habituation and emergence in socially reared and isolated rats

Abstract

Male and female hooded rats were weaned at 17 days and then reared in isolation or in social groups. Intersession habituation of locomotor activity in the open field was tested at 15, 25, and 45 days. Contrary to some previous reports, the 15-day-old animals showed significant habituation. At 45 days, however, the isolates showed very little habituation compared to the social animals. The isolates showed a similar pattern of development in their emergence into the open field. Apparently, isolation does not result in an arresting of development, but rather in the formation of behavior patterns otherwise absent in normally reared rats.

Social Isolation in the Rat Produces Developmentally Specific Deficits in Prepulse Inhibition of the Acoustic Startle Response Without Disrupting Latent Inhibition

“…The data are discussed with respect to the involvement of ventral striatal DA mechanisms in the expression of PPI and LI, differences in the impact of social isolation in young and adult animals, and the utility of social isolation model as a nonlesion, nonpharmacologic means of perturbing ventral striatal DA function. [Neuropsychopharmacology 10:61-72, 1994J conditioned locomotor activity (Gentsch et al 1981;Sa hakian et al, 1982;Jones et al, 1990), altered responses to environmental novelty (Sahakian et al 1977;Gentsch et al 1982aGentsch et al , 1982bGentsch et al , 1983, impairments in discrimina tion learning (Jones et al 1991), and resistance to ex tinction (Einon et al 1975;Morgan et al 1977). Rats iso lated in this way also show an increased sensitivity to psychomotor stimulant drugs such as d-amphetamine and cocaine, both in terms of the locomotor enhancing properties of these agents and their ability to induce stereotyped behaviors Jones et al 1990Jones et al , 1992, responses that depend on the meso lim bic and mesostriatal dopamine (DA) projections, respec tively (Kelly et al 1975).…”

Activity differences of individually and group-housed male and female rats

“…In contrast, reports of open-field hyperactivity in individually housed rats have usually used handled, well-habituated animals (Morgan, 1973), have repeatedly tested the animals (Einon, Morgan, & Sahakian, 1975), or have exposed them to long durations of open-field presentation (Sahakian et al, 1977). In the light of these comparisons, it appeared that the conditions and duration of the activity test and the prior experimental history might be especially important in determining the relative activity levels of individually and group-housed 1.e.…”

The effects of isolation rearing on exploration in the rat

“…Rats reared in isolation from weaning show several behavioral abnormalities. For example, they are more aetive in the open field (Einon, Morgan, & Sahakian, 1976;Mandell, Segal, Kuezenski, & Knapp, 1973;Morgan, 1973;Syme, 1973) and in photoeell activity eages (Sahakian, Robbins, Morgan, & Iversen, 1975). Isolates also show evidenee of retarded habituation, eompared with group-reared animals Sahakian et al, 1975).…”