A dual-task is a procedure in which subjects are asked to perform two tasks simultaneously. Humans often show performance deficits in one or both of the component tasks in the dual-task. This effect, known as dual-task interference, is thought to reflect the fundamental characteristics of higher-order cognitive functions such as attention and working memory, therefore human dual-task performance has been extensively studied in the fields of cognitive psychology and neuroscience. Despite many decades of research, our understanding regarding the mechanisms underlying dual-task performance is still limited due to the lack of animal models that are amenable to direct recording of neuronal signals during dual-task performance. In this review, we first outline the history of dual-task research in human cognitive psychology. We then review the major trends of dual-task research in human functional neuroimaging studies, and discuss how these studies contributed to the understanding of neural mechanisms underlying dual-task performance. Finally, we review recent advances in behavioral and neurophysiological studies in nonhuman primates, and discuss how the development of animal models of dual-task performance will shed new light in these areas.

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Activity budgets represent life styles, reproductive life points of females and patterns for habitat environment in animals. It is suggested that activity budget favor the worst environmental criteria and resting time becomes a buffer for increasing energy demand such as lactation. We studied the activity budgets of anubis baboons (Papio anubis) in the semi-arid Laikipia District of Kenya to investigate their behavioral strategies adapted for the dry months when available foods are poor. We found that 18.1 % of each day was devoted to feeding, 34.5 % to moving, 37.4 % to resting, and 10.0 % to participating in social interactions. Although this distribution of time did not change between the wet months and the dry months, the frequency of drinking water in the dry months was more than in the wet months. Anubis baboons switched their diet from insects in the wet months to herbaceous plants in the dry months. Comparison of the results with previous studies suggests that feeding time becomes short when group size is small.

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For the sake of population management in captivity three adult Japanese macaques (Macaca fuscata) were isolated from the originated group in Ueno Zoological Gardens, Tokyo, Japan, during a breeding season in 2014. I investigated social rank and social interactions of these males comparing with other group members among three phases (before, during, and after isolation). The most dominant male dropped his rank after isolation and changed his interaction partners. After the reintroduction of three males, most of individuals that remained in the group attacked to isolated males. The result suggest that temporal isolation caused drastic change in social interaction and that this manipulation might increase a risk of fight with injury in the group. Therefore we should consider number and combination of individuals isolate together at once, depend on situation of social structure inside the enclosure.

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The purpose of this study was to clarify the effects on Japanese macaques of being driven away by citizens. We studied transition-frequency and the number of people who drove away macaques, the macaque troop home range, haunt-frequency to human habitation and feeding-frequency on crops in Fujiyoshida and Fujikawaguchiko, Yamanashi Prefecture, Japan. Immediately after a meeting that was held to explain the study to local residents, the frequency with which macaques were driven away increased. However, the core macaque area did not move closer to human habitation and neither the feeding-frequency on crops nor the frequency of infestation decreased. Meetings with local residents provide opportunities to strengthen damage management, but this meeting did not reduce the damage caused by the macaque troop. In addition, the village that drove away the macaques has been excluded from the core area of the macaque troop and the frequencies of crop damage and haunting by macaques have decreased rapidly since June 2007, when the civic organization "Wildlife Damage Management Support Center" began driving away macaques in Fujiyoshida. The organization consists of a small number of citizens who drive away macaques, and their efforts indicate that crop damage can be reduced by moving macaques away from human habitation. On the other hand, the frequencies of feeding on crops and haunting by macaques are not higher in Fujikawaguchiko, where civic organizations aimed at driving away macaques have not been established.

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In some catarrhines, tails have extremely reduced. In order to clarify the tail reduction process in the catarrhines, understanding the sacro-caudal musculo-skeletal morphological variations with different tail lengths is essential. Although previous studies revealed that skeletal morphology strongly reflected tail length variation, caudal musculature has scarcely been studied. Thus, this study aimed to increase the knowledge about caudal musculature in catarrhines. Comparative dissection of both the dorsal and ventral side of the lumbo-sacro-caudal region in five individuals of five catarrhine species was performed, and following findings were obtained: 1) All caudal muscles tended to insert or become tendinous more cranially in shorter tailed species, 2) Ventral caudal flexors were completely lost in catarrhines with shorter tails than M. arctoides, 3) Pelvocaudal muscles were present regardless of the tail length, 4) Only one kind of dorsal caudal extensor muscle was observed in very short tails species and were lost in tailless species, and 5) Dorsal caudal abductors existed independently in all of tailed species and were lost in tailless Pan troglodytes. Together with the skeletal morphological perspective, these findings will be helpful for understanding the tail reduction process in catarrhines in the future.

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