A study of the physiological psychology to investigate the brain mechanisms of the hyperactive and learning disorders using Tsukuba emotional strain rats as an animal model of these disorders.

本研究旨在通过详细观察多动学习障碍大鼠的一般活动和各种学习习得过程，阐明多动学习障碍的脑机制，并确定L系筑波低情绪应激大鼠作为多动学习障碍动物模型的可行性。结果揭示了一个有趣的事实，即L系大鼠在空间学习问题上表现出明显的空间学习障碍，其中8臂放射状迷宫需要工作记忆。此外，在L系大鼠中观察到了特殊的昼夜节律，证实了L系大鼠多动学习障碍模型的有效性。主要对对空间记忆起重要作用的海马区进行的形态学研究表明，L系大鼠背海马吻侧部体积占整个海马区的体积比明显减小，齿状回占背海马区的体积比明显低于其他组。此外，研究结果还显示，L系大鼠的空间学习试验次数与齿状回体积比呈负相关。因此，从空间学习障碍的角度提出了海马齿状回的形态变化。

The present study was intended to clarify the brain mechanism of the hyperactivity and learning disorder, as well as to determine the appropriateness of Tsukuba low emotional strain (L strain) rats as an animal model of the hyperactive and learning disorder, by observing the general activity and various learning acquisition processes of these rats in detail. As a result, it revealed an interesting fact that the L strain rats showed a clear spatial learning disorder in the spatial learning problem with an 8-arm radial maze needing a working memory. In addition, peculiar circadian rhythm was observed in the L strain rats, and the validity of the hyperactive and learning disorder model of the L strain rats was confirmed. The morphological study mainly performed on the hippocampus which was important to spatial memory made very obvious that the volume ratio of the rostral part of the dorsal hippocampus for the whole hippocampus significantly decreased in the L strain rats, and that the volume ratio of the dentate gyrus for the dorsal hippocampus in these strain rats was quite lower compared with that in the other rats. Moreover, the findings displayed the negative correlation between the number of trials achieved in the spatial learning and the volume ratio of the dentate gyrus in the L strain rats. Therefore, the morphological transformation of the hippocampal dentate gyrus was suggested in terms of the spatial learning disorder.