Effect of rearing condition on body weight. A. Average weekly body weight of group housed (GH) and socially isolated (SI) rats during the six week housing manipulation (N= 16 GH, 17 SI; error bars fall within symbols). B. Body weight of group housed, socially isolated, and age-matched standard housed ( N = 17) rats assessed on postnatal day 70, prior to the onset of behavioral testing. (*, significant difference relative to GH and SI rats, P < 0.001).