京都大学 / 新制・論文博士 / 博士(医学) / 乙第13525号 / 論医博第2271号 / 新制||医||1062(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 井上 治久, 教授 大森 孝一, 教授 古川 壽亮 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

Understanding why animals make the foraging choices they do has been an interdisciplinary research goal for decades. This question is especially salient in biological anthropology, as we seek to understand how the human diet evolved by looking to non-human primate models. Optimal Foraging Theory (OFT), and more recently the Geometric Framework for Nutrition (GF) and Movement Ecology paradigms provide models and heuristics that aid in our understanding of what drives the foraging decisions of animals. Yet until recently, most research examining the foraging decisions of frugivorous herbivores has focused on the OFT based strategy of maximizing and obtaining fruit foods. My research examines alternative nutrient priorities in a frugivorous primate, the Bornean orangutan (Pongo pygmaeus wurmbii), to determine whether fruit-seeking and energy maximization form a sufficient explanation of foraging behavior. Using behavioral and geospatial data from full-day focal animal follows collected in 2015-2016 in Gunung Palung National Park, I first demonstrate that orangutans leave available fruit resources to eat non-fruit foods, suggesting that orangutans are intentionally seeking out non-fruit foods, and clearing the way for a foraging model beyond strict energy maximization via fruit seeking. Further, I find that orangutans do consume non-fruit food when fruit is in visual proximity. I next test whether the Marginal Value Theorem (MVT) of OFT can account for these fruit patch departures by testing one critical assumption of MVT – that feeding rates in a patch decrease over time. Feeding rates did not decrease over patch residence, thus MVT does not explain orangutan fruit patch departures. Instead, I find that orangutans maintain an average 10:1 ratio of non-protein energy to protein, and prioritize protein intake. These findings could explain fruit departure. Geospatial data suggest that fruit is not the only goal of orangutan foraging and that these apes navigate to other food types, in particular, leaves. Taken together, these findings suggest that GF provides a good explanation of orangutan foraging in tandem with OFT energy maximization. I discuss the similarities in nutrient goals between orangutans, modern humans, and extinct hominins, and the conservation implications of my research. / 2021-06-19T00:00:00Z

Handedness is a widely studied behavioral asymmetry that is commonly measured as a preference for using one hand over the other. Right hand preference in humans occurs at a ratio of 9:1, whereas left hand preference in rhesus monkeys has been estimated at 2:1. Despite differences in the direction and degree of hand preference, this dissertation investigated whether primates share common underlying factors for the development of handedness. Previous work in human infants has identified a predictive relationship between rightward supine head orientation and later right hand preference. Experiment 1 examined the relationship between neonatal head orientation and later hand use in rhesus monkey infants (N=16). A leftward supine head orientation bias was found that corresponded to greater left hand activity for hand-to-face movements while supine; however, neonatal head positioning did not predict later hand use preference for reaching or manipulation on a coordinated bimanual task. A supine posture is common for human infants, but not for rhesus monkey infants, indicating that differences in early posture experience may differentially shape the development of hand use preference. Movement quality is an additional factor that may affect how the hands are used in addition to neonatal experience. 2-D and 3-D kinematic analyses were used to examine the quality of reaching movements in rhesus monkey infants (N=16), human infants (N=73) and human adults (N=12). In rhesus monkey infants, left hand reaches were characterized as ballistic as compared to right hand reaches independent of hand use preference (Experiment 2). Left hand ballistic reaching in rhesus monkeys may be a carryover from earlier primates that relied on very fast reaches to capture insect prey. Unlike monkey infants, reach quality was a function of hand preference in human infants (Experiment 3). By contrast, a right hand advantage for reaching was observed in human adults regardless of left or right hand preference (Experiment 4). Differential hand experience due to hand preference in early infancy may in part be responsible for the hand preference effects on movement quality observed in human infants but not monkey infants. Motor control may become increasingly lateralized to the left hemisphere over human development leading to the right hand advantage for reaching observed in human adults, as well as over primate evolution leading to right hand use preferences in higher primates like chimpanzees. An underlying mechanism such as a right shift factor in humans and a left shift factor in rhesus monkeys may be a common basis for primate handedness. Environmental and experiential factors then differentially shape this mechanism, including species-typical development. Further work examining the ontogeny of hand preference and hemispheric specialization in various primate infants will lead to a greater understanding of how different factors interact in the development of hand use across primate species.

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<p>Previous studies have found that DNA flanking low-complexity regions (LCRs) have an increased substitution rate. Here, the substitution rate was confirmed to increase in the vicinity of LCRs in several primate species, including humans. This effect was also found within human sequences from the 1000 Genomes Project. A strong correlation was found between average substitution rate per site and distance from the LCR, as well as between the proportion of genes with gaps in the alignment at each site and distance from the LCR. Along with substitution rates, dN/dS ratios were also determined for each site, and the proportion of sites undergoing negative selection was found to have a negative relationship with distance from the LCR.</p> <p>Low-complexity regions in proteins often form and extend through the gain or loss of repeated units, a process that is dependent on the presence of a relatively pure string of repeats. Any interruption should disrupt the mechanisms of LCR extension and contraction, inhibiting LCR formation. Despite this, several examples have been found of LCR-coding DNA which are interrupted by introns. While many of these LCRs may be the result of two shorter LCRs forming on opposite sides of an intron, shuffling the order of exons showed that more intron-interrupted LCRs exist than would be expected to occur randomly. Another possible explanation for this phenomenon is the apparent movement of either the LCRs or introns, possibly through recombination or the appearance of new splice sites through the gain of repeat units.</p> / Master of Science (MSc)

Primates are the closest living relatives of Homo sapiens and are an important model for understanding human origins. From studying primates and making comparisons to what we know from the hominid fossil record, we can elucidate and make inferences into human physical and social evolution. My research focuses on the social aspects of primate life and attempts to find significant correlations between primate biology and social structure. Specifically, I am interested in how dominance hierarchies and power relationships between male and female primates are established and maintained in primate communities. This study contains a comprehensive dataset on a large sample of known primate species, predominantly from previously published sources and studies. For each primate species, the variables included are body mass, level of sexual dimorphism, brain size, habitat type, diet, life span, age at sexual maturity, gestation length, birth interval, locomotion type, social structure, terrestrial or arboreal locomotion, group size, home range, nocturnal or diurnal, philopatric sex, and dominant sex. Pearson's correlation coefficients between the above variables were calculated. The goal of this research is to determine what factors of primate life, both social and biological, have the largest influence on the formation and maintenance of dominance hierarchies. Certain biological variables related to body mass were found to be correlated with dominance. However, the correlation with sexual dimorphism was not found to be statistically significant and it is presumed that other ecological variables should be studied to better understand primate power relations.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Les fonctions exécutives (FE) sont définies comme des processus de contrôle permettant d'adapter les comportements dans des situations nouvelles. La littérature sur l'homme fait état de fortes variabilités interindividuelles dans l'exécution de ces FE, notamment liées à l'âge des individus. Dans une approche comparative, nous avons cherché à savoir si le primate non humain exprimait de telles variabilités interindividuelles, dans quelle mesure, et pour quelle(s) fonctions(s). Nous avons proposé une série de tâches à un groupe de babouins Papio papio où des individus mâles et femelles d'âges différents, et de statuts sociaux différents cohabitent. Ces expériences ont bénéficié de l'environnement exceptionnel de la plateforme de Comportement et Cognition du Primate située sur la station de Primatologie CNRS de Rousset, où un groupe de babouins a accès ad libitum à dix systèmes de conditionnement opérant automatisés. Les tâches proposées impliquaient chacune une FE particulière, notamment les fonctions d'inhibition et de flexibilité cognitive. Les procédures utilisées, qui reposent sur un principe de conditionnement opérant, consistaient à présenter les tâches sur des écrans tactiles sur lesquels les babouins devaient donner leur réponse. Les expériences impliquant principalement l'inhibition ont montré que le babouin est capable de mettre en place un contrôle inhibiteur efficace. Cependant, les individus les plus âgés montrent des déficits dans leurs performances. Au contraire, lorsque la tâche d'inhibition a une forte composante motrice, les jeunes ont plus de difficultés à adapter leur mouvement. / Executive functions (EF), which are defined as control processes, serve the adaptation of the behaviour in new situations. The human literature reveals important inter-individual variabilities in the efficiency of EF, in particular when age is considered. In a comparative perspective, we investigated if similar individual differences also exist in nonhuman primates, and for which function(s). Several tasks were thus proposed to a group of baboons Papio papio, comprising individuals of both sexes and different ages and social status. These experiments were run in a unique research facility, the Primate Behaviour and Cognition platform (Primatology center, Rousset-sur-Arc), where the baboons had an ad libitum free access to ten automated operant conditioning test systems equipped with touch screens. Each task targeted a particular EF, including the functions of inhibition and cognitive flexibility. The baboons demonstrated an efficient inhibitory control in our tasks. Overall, older individuals showed deficits in inhibitory control when compared to the younger subjects. However, this pattern of results is inverted when motor rather than cognitive inhibition was required. The second set of experiments studied cognitive flexibility. That EF appears deficient in adults, in comparison to the younger individuals. Thus, as in humans, monkeys show significant individual differences in executive control. It is concluded that their analysis requires to distinguish motor from cognitive inhibition, and to pay special attention to the factor of age.

Lors d'une tâche cognitive telle que la navigation spatiale dans un environnement connu, l'individu peut utiliser des stratégies différentes pour atteindre un but. Il peut baser sa navigation sur une représentation mentale de l'espace (globale) ou utiliser une stratégie mettant en jeu des informations égocentriques ou associatives (indices physiques internes ou externes associatifs). Deux grands systèmes cérébraux sont impliqués dans l’apprentissage spatial : la formation hippocampique et les ganglions de la base. Ces deux systèmes utilisent des modalités différentes : l'hippocampe est plus spécifiquement lié à l'apprentissage par rapport à un référentiel externe (apprentissage allocentrique) alors que les ganglions de la base sont plutôt liés à l'apprentissage par rapport à un référentiel interne (apprentissage égocentrique). L’apprentissage parallèle entre les deux systèmes partage à la fois des aspects compétitifs et coopératifs. L’hippocampe étant peu atteint dans les stades précoces de la maladie de Parkinson, ceci fournit l'opportunité de développer des méthodes de rééducation basées sur le renforcement de l'apprentissage allocentrique. Dans cette optique, il faut tout d'abord bien comprendre le fonctionnement de ces mécanismes d'apprentissage dans le cerveau sain. Nous proposons ici un test qui vise à analyser les processus d'apprentissage des deux systèmes, pendant une tâche de navigation dans un labyrinthe. Nous voulons développer une variante de cette tâche qui permet de différencier le rôle respectif de l'hippocampe et des ganglions de la base dans ces processus d'apprentissage. L’objectif de cette étude est d'étudier les différentes modalités d'apprentissage spatial (allocentrique et egocentrique) afin de définir leurs cinétiques d'apprentissage et les interactions entre ces deux systèmes. Ces connaissances seront utilisées par la suite afin de pallier au déficit spécifique d'apprentissage égocentrique dans la maladie de parkinson. Ce projet a pour but de mettre au point une tâche de navigation spatiale permettant de mieux connaitre les modalités des différentes stratégies utilisées lors de la navigation spatiale chez le primate dans un premier temps. Ces données pourront éventuellement servir à l'ajustement d'un protocole pour des sujets humains sains ou souffrant de déficits cognitifs pouvant être compensés par l'adaptation stratégique. / In spatial navigation task, we can use several strategies to reach a goal. We can build a mental representation (global) of the environment, use egocentric (body-based) information or use available cues (internal or external). Two structures known to have roles in spatial information are the hippocampus and the striatum. It is now generally held that allocentric (external reference frame) learning is related to the hippocampus. On the other hand, the striatum is believed to be involved in egocentric representation. There is a parallel processing between those two system which sharing both competitive and cooperative interactions. The hippocampus is less damaged in the early stages of Parkinson disease, this aspect allows the possibility to develop rehabilitation protocols based on the use of allocentered learning when the egocentered one is biased. We have first to better understand how these two systems functionally operate in the normal brain. Here we present a task which permits the study of the spatial learning processes in a maze. Our global aim is to differentiate the respective functions of the hippocampus and basal ganglia in the spatial learning modalities (allocentered or egocentered) and define their kinetics and interactions. The resultant knowledge will may serve to develop cognitive rehabilitation tasks for people with cognitive disorders can be compensated by strategic adaptation.