Recent human neuroimaging studies indicate that by using fMRI we can “see” what people are thinking. In animals, we can more accurately see what the animal has in mind by using invasive methods that cannot be used in human subjects. Here I introduce experimental studies where single neuronal activities were examined in the monkey prefrontal cortex in relation to working memory and reward expectancy. We found that by monitoring the neuronal activity while the animal is waiting for the next event, we can see what the monkey is retaining or expecting in mind. Human neuroimaging studies have well documented “default mode of brain activity”, which is higher activity during the resting state than during cognitively demanding task, and is concerned with internal thought processes, in the medial prefrontal and medial parietal areas. In our PET study, we also found higher activity during rest in these medial cortical areas of the monkey. The result suggests that there are primitive-level internal thought processes in the monkey.

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Horses (Equus caballus) have lived with humans for over 5500 years. Despite this, their cognitive abilities have not received much research attention compared with those of dogs (Canis familiaris), probably because horses are not as familiar to humans as dogs and have been considered to be difficult to test. Recent studies, however, have revealed their sophisticated social cognitive abilities with regard to both conspecifics and humans. In this paper we first describe fundamental characteristics of horse perception and horse sociality. Then, we review horses' learning and cognitive abilities, especially social cognitive abilities shown among conspecifics and in the horse-human relationship. Several studies have provided evidence that horses possess sensitivity to human-given cues and attentional states. Future studies should investigate ontogeny of horses' cognition and the influence of effects including training history and the exposure to humans, and possibly test how such cognition is supported by genetics.

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Though estrogens are well known to regulate anxiety or fear-related behavior, controversial effects of estrogen replacement to ovariectomized rodents were reported. This inconsistency may be due to differences in the treating condition of estrogens, such as duration of administration and/or their total amount. The present study was conducted to address these issues by examining the effect of chronic treatment of estradiol benzoate (EB) in ovariectomized ICR/Sea mice with several different doses of EB and intermittent observation of anxiety-related behavior in several tests [open field (OF), elevated plus maze (EPM), light-dark transition (LDT)]. The behavioral parameters of the tests were subjected to factor analysis. As the results of comparing the factorial scores for two extracted factors, it was indicated that the mice implanted with relatively higher-dose EB capsule were more anxious than the animals treated with vehicle and/or lower-dose EB. While, the mice treated with the lower-dose EB did not show apparent change of anxiety. Together, the findings in the present study suggest that the chronic estrogen treatment may have anxiogenic effects in higher doses, while the effects were not clear in lower doses.

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