Tsukuba 情動系ラットの作業記憶能力について : 物体認知課題による検討

The author conducted a study to examine the“ pure" working memory ability of Tsukuba High (H) and Low (L) emotional strain rats using an object recognition task in comparison of that of Wistar (W) strain rats similarly examined as a control. The study consisted of two sessions. In the first session, the rats were each subjected to a first trial for exposure to two identical objects (samples) for two minutes, followed (with a delayed time of five minutes) by a second trial in which they were each exposed to two different objects; one the same object as used in the first trial (familiar as the sample) and the other a novel object, for two minutes, to measure the time spent by each rat for spontaneous exploration of both objects in each of the first and second trials. 48 hours after the end of the first session, the second session was performed on the rats in the same manner as in the first session, except using different objects from those used in the first session. The results of the study can be summarized as follows: the H and W rats spent significantly longer time for exploration of the novel objects than the familiar objects, while the L rats showed no such tendency; and the habituation components (h1, h2) and mnemonic components (d2, d3) of the L rats were significantly lower than those of the H and W rats. From the above, it was concluded that the L rats were inferior to the H and W rats, not only in their spatial working memory ability, but also in their non-spatial visual working memory ability.