Black J E, Sirevaag A M, Wallace C S, Savin M H, Greenough W T
College of Medicine, University of Illinois, Urbana-Champaign.
Dev Psychobiol. 1989 Nov;22(7):727-52. doi: 10.1002/dev.420220707.
Rats kept in complex environments (EC) show an array of brain changes relative to animals housed individually (IC). These effects have been explained as due to (a) information storage, (b) chronic stress that causes brain damage, or (c) neuroendocrine effects on brain maturation. Complex experience also affects somatic growth and organ development, and these may be related to the EC/IC brain differences. We have compared somatic growth and internal organs of 315 weanling and adult rats with various histories. (a) Young EC rats showed slower skeletal and visceral growth, while many brain components expand. (b) Although thymus and spleen were lighter in young ECs, immunocompetence was nonsignificantly (p less than .07) higher than in ICs. (c) Somatic growth of adult rats was slow and not very responsive to experience, whereas studies have shown EC/IC brain effects similar to those in young rats. (d) Males had slightly greater EC/IC somatic and visceral differences. (e) The stress index, adrenal weight, varied across age and experience, so chronic stress can not explain EC/IC brain differences. Training paradigms show brain changes similar to those from complex experience, occurring specifically with learning and in brain regions using the information. Learning and memory, therefore remain the best explanation of the EC brain effects.
饲养在复杂环境（EC）中的大鼠相对于单独饲养的动物（IC）表现出一系列大脑变化。这些影响被解释为是由于：（a）信息存储；（b）导致脑损伤的慢性应激；或（c）对大脑成熟的神经内分泌影响。复杂的经历也会影响身体生长和器官发育，而这些可能与EC/IC大脑差异有关。我们比较了315只具有不同经历的断奶大鼠和成年大鼠的身体生长及内部器官。（a）年幼的EC大鼠骨骼和内脏生长较慢，而许多脑成分会扩张。（b）虽然年幼的EC大鼠胸腺和脾脏较轻，但免疫能力比IC大鼠略高（p小于0.07）。（c）成年大鼠的身体生长缓慢，对经历的反应不太明显，而研究表明EC/IC大脑效应与年幼大鼠相似。（d）雄性大鼠的EC/IC身体和内脏差异略大。（e）应激指数，即肾上腺重量，随年龄和经历而变化，因此慢性应激无法解释EC/IC大脑差异。训练范式显示出与复杂经历相似的大脑变化，特别是在学习过程中以及使用该信息的脑区中出现。因此，学习和记忆仍然是对EC大脑效应的最佳解释。
