進化 Evolution
P2-1-106 MRI voxel-based morphometryによるフェレット大脳形態の性差解析 Sexual dimorphism of cerebral morphology in ferrets analyzed by MRI voxel-based morphometry ○澤田和彦1, 廣瀬美和2, 齋藤茂芳3, 青木伊知男4 ○Kazuhiko Sawada1, Miwa Horiuchi-Hirose2, Shigeyoshi Saito3, Ichio Aoki4 つくば国際大・保・理学1, つくば国際大・保・栄養2, 大阪大学・医・保健3, 放医研・分子イメージング4 Dept Phys Ther, Fac Med Health Sci, Tsuckuba Int Univ, Tsuchiura, Japan1, Dept Nutr, Fac Health Sci, Tsukuba Int Univ, Tsuchiura, Japan2, Dept Med Engineer, Div Health Sci, Osaka University Grad Sch Med, Suita, Japan3, Mol Imaging Cent, Nal Inst Radiol Sci, Chiba, Japan4 The present study aimed quantitatively to characterize the cerebral morphology in young adult ferrets using MRI-based voxel-based morphometry. Ex vivo T1W-MRI with high spatial resolution at 7-tesla could visualize major subcortical and archicortical structures, and the cortical surface morphology with sulci and gyri. Three-dimensional (3D) rendered images could reproduce well those cerebral structures. The cerebrum marked significantly lower volumes in female than in males, which were attributed to region-specific volume reduction in the cerebral cortex and subcortical white matter in females. The gray level image (GLI) of T1W-MRI exhibited unique values in each cerebral structure with region-nonspecific lower and higher values in females than in males, respectively. Interestingly, the GLI of T1W-MRI was heterogeneous throughout the cerebral cortex. An array of higher and lower GLI transverse zones, which was reminiscent the functional cortical areas, was revealed by the maximum intensity projection (MIP) in 3D. GLI values in the cortex were negatively correlated with the density of myelin-basic protein immunoreactive fibers. The present results suggest that sexual difference in the adult ferret cerebrum is characterized by reduced volumes in the cerebral cortex and subcortical white matter in the female ferret cerebrum. It should be noted that T1W-MRI-based MIP delineated functional cortical areas related to myeloarchitecure in 3D. Ethics: approved by the Institutional Animal Care and Use Committee of Tsukuba International University. Grant: supported by JSPS KAKENHI (23590223)	P2-1-107 チンパンジーとヒトにおける周産期の脳容積の成長様式の比較 Estimated prenatal growth patterns of brain volume in chimpanzees versus humans ○酒井朋子1, 三上章允2, 平田聡1, 竹下秀子3, 松井三枝4, 濱田穣1, 友永雅己1, 松沢哲郎1 ○Tomoko Sakai1, Akichika Mikami2, Satoshi Hirata1, Hideko Takeshita3, Mie Matsui4, Yuzuru Hamada1, Masaki Tomonaga1, Tetsuro Matsuzawa1 京都大学霊長類研究所1, 中部学院大学リハビリテーション学部2, 滋賀県立大学人間文化学部3, 富山大学 / 大学院・医学薬学研究部(医学)4 Primate Research Institute, Kyoto University1, Faculty of Rehabilitation, Chubu Gakuin University2, Department of Human Relations Studies, Shiga Prefecture University3, School of Medicine, Toyama University4 Elucidating the differences between humans and non-human primates in the ontogenetic mechanism underlying brain structure is important to understand the remarkable brain enlargement in humans. It is argued that the brain enlargement observed in humans is due to not only the human-specific pattern of postnatal brain development, but also to that of prenatal brain development. However, the developmental trajectory of the brain has not been explored in our closest living primate relatives, the chimpanzees. To address this lack of information and obtain empirical evidence about the remarkable enlargement of the human brain, we tracked development of the brain in growing chimpanzees from infancy to the juvenile period using three-dimensional (3D) magnetic resonance imaging (Sakai et al., Current Biol. 2011; Sakai et al., Proceedings B. 2012). Moreover, we determined the fetal growth pattern of the chimpanzee brain using 3D ultrasound imaging (Sakai et al., Current Biol. 2012). Here, as a further step, we determined the prenatal growth patterns of brain volume in chimpanzees by analysis of combined data from these imaging methods and compared it with that of the human brain during approximately the same period. We found that the brain volume of chimpanzee fetuses was only half that of human fetuses at 16 weeks of gestation. Moreover, although the velocity of brain volume growth increased until approximately 22 weeks of gestation in both chimpanzees and humans, chimpanzee fetuses did not show the same accelerated increase in brain volume as human fetuses therafter. However, interestingly, the velocity of human brain volume growth decreased once between the period of approximately 30 weeks of gestation and one month after birth, and increased again between the period of one month and 1 year after birth. This suggests that a dynamic growth of the human brain volume during the perinatal period contributes to the more remarkable brain enlargement observed in humans.
P2-1-108 マカクザルの道具使用からヒトの脳進化の分子基盤を探る研究 Molecular basis of human brain evolution: insights from macaque tool-use study ○松永英治1, 南部菜奈恵1, 岡真里子1, 田中美智雄1, 田岡三希1, 入來篤史1 ○Eiji Matsunaga1, Sanae Nambu1, Mariko Oka1, Michio Tanaka1, Miki Taoka1, Atsushi Iriki1 独立行政法人理化学研究所　脳科学総合研究センター　象徴概念発達研究チーム1 Lab for Symbolic Cognitive Development, RIKEN BSI, Wako1 Japanese macaques are able to learn how to use rakes to take foods by a few weeks training. Voxel-based morphometry (VBM) study revealed that gray and white matter is expanded during tool-use learning process even in the adult monkeys. Thus, tool-use training in macaque monkeys is a good model to explore molecular basis of neural plasticity in the primate brain. To explore the molecular mechanism, we performed comprehensive gene expression analysis with Rhesus macaque microarray. We identified 120 genes highly expressed in the tool-use monkeys than control monkeys and 106 genes lowly expressed in the tool-use monkeys. In these tool-use associated genes, we found various genes involved in neural development such as cell growth, neuronal differentiation, axon guidance and synaptic plasticity. Furthermore, we performed comparative gene expression analysis among rodents (mice), new world monkeys (marmosets) and old world monkeys (Japanese macaques), and found that some of these tool-use associated gene expressions are different among these species. Thus, the possibility is suggested that diverse expressions of plasticity-related genes have led to evolution and diversity of neocortical plasticity.	P2-1-109 新世界ザルの生後発達期の終脳におけるカドヘリンの発現パターンと、霊長類脳の進化への関与の可能性 Differential cadherin expression in the developing postnatal telencephalon of a New World monkey suggests the possible involvement of primate brain evolution ○南部菜奈恵1, 松永英治1, 岡真理子1, 入來篤史1 ○Sanae Nambu1, Eiji Matsunaga1, Mariko Oka1, Atsushi Iriki1 理化学研究所　脳科学総合研究センター　象徴概念発達研究チーム1 Lab for Symbolic Cognitive Development, BSI, RIKEN, Saitama1 Cadherins are cell adhesion molecules widely expressed in the nervous system, where they play various roles in neural patterning, nuclei formation, axon guidance, and synapse formation and function. Although many published articles have reported on cadherin expression in rodents and ferrets, there is limited data on their expression in primate brains. In this study, we performed in situ hybridization analysis of 10 cadherins (9 classic cadherins: Cdh4, -6, -7, -8, -9, -10, -11, -12, -20; and 1 T-cadherin (Cdh13)) in the developing postnatal telencephalon of the common marmoset (Callithrix jacchus). Each cadherin showed broad expression in the cerebral cortex, basal ganglia, amygdala, and hippocampus, as previously shown in the rodent brain. However, detailed expression patterns differed between rodents and marmosets. In contrast to rodents, cadherin expression was reduced and localized to restricted areas of the brain during the developmental process; thus suggesting that cadherins are more crucially involved in developmental or maturation processes rather than in neural functioning. Our results also highlight the possibility that restricted/less redundant cadherin expression allows primate brains to generate functional diversity among neurons, enabling morphological and functional differences to occur between rodents and primates.

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