Japanese macaques, Macaca fuscata, often utter girneys and 'short low' coos when they begin grooming interactions. In a captive group of Japanese macaques, instances of grooming of others by females were compared to cases in which they received grooming with regard to kinship and dominance relations. For unrelated females, dominant females vocalized more frequently when they received grooming than when they groomed subordinates. In contrast, subordinate females vocalized more frequently when they groomed a dominant female than when they received grooming. However, even when each case was examined individually, grooming was not consistently preceded by vocalizations. Generally, females uttered these vocalizations more frequently to unrelated females than to related females. On the other hand, solicitation of unrelated dominant females was infrequent. These results suggest that grooming partners and roles in grooming do not always determine the pattern of vocalization; instead, female monkeys may utter these vocalizations to reduce tension.

抄録全体を表示

Intrastriatal kainic acid (KA) administration induces selective neuronal cell death in the striatum sparing passing nerve fibers and terminals. Although performance deficits of several kinds of learning tasks have been reported in striatal KA-lesioned rats, the problem remains unsolved whether these animals can discriminate visual stimuli to acquire such learning tasks. This study investigated, therefore, the effects of intrastriatal KA administration on the acquisition of vertical vs. horizontal stripe discrimination learning. Striatal KA-lesioned rats did not show any deficit in the process of learning this task in comparison with vehicle-treated control rats. Results suggest that learning deficits that have been reported in animals with a loss of striatal neurons cannot be explained by deficits of visual discrimination ability such as measured in this study.

抄録全体を表示

The effects of pre-exposure of conditioned stimuli (CS) on subsequent shuttle-box avoidance learning were examined in rats. Two intensities of tone were used as the CS. The first and second groups were trained using high-and low-intensity CS, respectively, without any CS pre-exposure (control groups). The third group was trained using the low-intensity CS following the pre-exposure of the same CS (unchanged group). The fourth group was also trained using the low-intensity CS, but it had been pre-exposed to the high-intensity CS (decreased group). The final group was trained using the high-intensity CS with the low-intensity CS pre-exposure (increased group). The avoidance learning was retarded in the three experimental groups compared to the control groups (latent inhibition). However, the greatest retardation was shown in the unchanged group, next in the decreased group, and the least in the increased group.

抄録全体を表示