Tonkiss J, Foster G A, Galler J R
Center for Behavioral Development and Mental Retardation, Boston University School of Medicine, MA 02118.
Brain Res Bull. 1991 Dec;27(6):809-13. doi: 10.1016/0361-9230(91)90213-4.
Developing rats were either malnourished or well-nourished during the prenatal period by feeding their dams diets of low (6% casein) or adequate (25% casein) protein content 5 weeks prior to mating and throughout pregnancy. All pups were well-nourished from the day of birth onwards. Male offspring aged 107 days were gradually reduced to 80% of their free-feeding weight. When weights were stable they were trained to run in an alley for food rewards given on every trial (continuous reinforcement, CR) or on a random 50% of trials (partial reinforcement, PR), then the running response was extinguished. A very clear and similar partial reinforcement extinction effect (PREE) was demonstrated in the previously malnourished and control rats when reward was discontinued. That is, PR groups showed greater persistence as compared with CR groups. During acquisition, however, differences in running speed were observed in the goal section between 6-25 PR and 25-25 PR groups, and between 6-25 CR and 25-25 CR groups. The latter may be due to differences between the nutritional groups in food motivation.
在交配前5周及整个孕期，通过给孕鼠喂食低蛋白（6%酪蛋白）或充足蛋白（25%酪蛋白）含量的日粮，使发育中的大鼠在产前阶段处于营养不良或营养良好状态。所有幼崽从出生之日起均营养良好。107日龄的雄性后代体重逐渐降至自由进食体重的80%。当体重稳定后，训练它们在一条通道中奔跑以获取每次试验（连续强化，CR）或随机50%的试验（部分强化，PR）中给予的食物奖励，然后消除奔跑反应。当奖励停止时，在先前营养不良的大鼠和对照大鼠中均表现出非常明显且相似的部分强化消退效应（PREE）。也就是说，与CR组相比，PR组表现出更大的持续性。然而，在习得过程中，6 - 25 PR组与25 - 25 PR组之间以及6 - 25 CR组与25 - 25 CR组之间在目标区域观察到奔跑速度的差异。后者可能是由于营养组之间在食物动机方面的差异。
