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感覚運動制御/学習2 Sensorimotor control/learning 2
O1-8-2-1 レンチウイルスベクターを用いた、ラットバレル皮質における局所的なNMDAR1のノックダウン Lentivirus-mediated RNAi for local knockdown of NMDAR1 in adult rat barrel cortex ○坪田匡史1, 大橋陽平1, 田村啓太1, 矢口雅江1, 松山真1, 関根岳1, 宮下保司1 ○Tadashi Tsubota1, Yohei Ohashi1, Keita Tamura1, Masae Yaguchi1, Makoto Matsuyama1, Takeru Sekine1, Yasushi Miyashita1 東京大学大学院 医学系研究科 統合生理学教室1 Dept. of Physiol., The Univ. of Tokyo Sch. of Med., Tokyo, Japan1 In rodents, barrel cortex neurons exhibit experience-dependent plasticity (EDP) of the physiological responses to whisker stimulation in adult as well as during development. NMDA receptor (NMDAR), one of the major mediators of synaptic plasticity, has been shown to be necessary for the expression of adult EDP in barrel cortex mainly by gene knockout approaches. However, to examine gene functions within the barrel circuit which has a clearly defined columnar structure, viral vector-mediated RNA interference approach would be beneficial because it can downregulate gene expression in a spatially limited manner. In the present study, we knocked down the NR1 subunit of NMDAR using lentiviral vectors which encode shRNA targeting NR1, and examined its impacts on EDP in adult rats. Several shRNAs were first screened in vitro and two highly efficient sequences (knockdown efficiencies: 91 and 85%) were chosen for in vivo experiments. For in vivo NR1 knockdown, a small volume (200 nl) of the lentiviral vector was injected into the center of D2 barrel which was identified by intrinsic signal optical imaging. We achieved layer II/III (LII/III)- and single barrel-limited expression of shRNAs by this injection method, as confirmed by histological analysis. Two weeks after injections, all whiskers except D1 were removed and whisker deprivation persisted for more than 3 weeks. Following 6 to 8-day whisker regrowth, we recorded extracellularly activities of LII/III regular spiking neurons in D2 barrel and examined their responses to D1 whisker deflections. In NR1 knocked-down rats, experience-dependent elevation of D2 neuron responses were significantly impaired compared to rats which express the negative control shRNA and to WT rats. Therefore, our results provide direct evidence for the involvement of cortical LII/III NMDAR in the expression of adult EDP. We are currently investigating further the impacts of local knockdown, in particular on the infragranular layer neurons.	O1-8-2-2 把握運動制御における複数下行路の役割－皮質脊髄路と赤核脊髄路の上肢筋群への投射様式からみた機能的分化 Functional specialization of parallel descending motor pathways for prehension, revealed by synaptic linkages of cortical versus rubral systems with forelimb muscles for the macaque monkey ○大屋知徹1,2, 武井智彦1, 関和彦1,3 ○Tomomichi Oya1,2, Tomohiko Takei1, Kazuhiko Seki1,3 国立精神・神経医療研究センター　神経研究所　モデル動物開発研究部1, 日本学術振興会2, さきがけ　科学技術振興機構3 Department of Neurophysiology, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Japan1, Japan Society for the Promotion of Science2, PRESTO, Japan Science and Technology Agency3 Corticomotoneuronal (CM) cells and rubromotoneuronal (RM) cells give rise to major synaptic inputs to spinal motoneurons via parallel descending motor pathways and reportedly play a crucial role in prehension for primates. However, functional implications of the two parallel systems are still unclear.To address the issue, we revealed functional synaptic linkages (post spike effects, PSEs) between a neuron and forelimb muscles using the spike triggered averaging (STA) technique, thereafter compared the PSE distributions between CM and RM cells. For STA, we recorded the single-unit electrophysiological activities of cortical or rubral cells concurrently with EMG activities from the 25 muscles including shoulder, upper arm, forearm, and hand muscles while a Japanese monkey was performing a sequence of whole-limb movements consisting of reach-to-grasp-and pull of a ball-shaped object (i.e., whole-hand grip), precision grip of pellets, and transportation of pellets to mouth. We identified 93 CM cells with 221 cell-muscle pairs, and 76 RM cells with 322 cell-muscle pairs. The PSE distributions highlighted distinct differences between CM and RM systems. First, CM cells have distally-biased projections with the small muscle field (1.70±1.09), as compared to proximally-biased projections with the large muscle field (2.42±1.70) for RM cells. Second, CM cells innervate more functionally similar muscles, whereas RM cells innervate more functionally different muscles. Third, while the majority of CM cells induced the PSEs with the same polarity (e.g.., exclusive facilitation) in different muscles, the PSEs for RM cells were more intermingled, particularly reciprocal among muscles. These contrasting results suggest that CM and RM systems are specialized for each unique function in primate prehension; CM system has a key role in fine-tuned control of grasping, whereas RM system is utilized to generate crude, alternating and/or inter-joint coordinated muscle patterns.
O1-8-2-3 神経ペプチドによる学習効果の条件選択的な反映のメカニズム：線虫C. elegansの匂い応答行動をモデルとして Direction-selective behavioral modulation regulated by peptide signaling in C. elegans ○山添萌子1, 藤田幸輔1, 岩崎唯史2, 飯野雄一3, 木村幸太郎1 ○Akiko Yamazoe1, Kosuke Fujita1, Yuishi Iwasaki2, Yuichi Iino3, Kotaro Kimura1 大阪大院・理・生物科学1, 茨城大・工・知能システム工学2, 東大院・理・生物化学3 Dept of Biol. Sci., Grad. Sch. of Sci., Osaka Univ., Osaka1, Dept. of Intel. Sys. Eng., Ibaraki Univ., Ibaraki2, Dept of Biophys. and Biochem., Grad. Sch. of Sci., Univ of Tokyo, Tokyo3 Animals modify sensory behaviors by learning. However, how behaviors are modulated by learning and how specific molecules are involved in this process are not well understood. Here, we report that the nematode Caenorhabditis elegans effectively avoids repulsive odor in a direction-selective manner because of non-associative learning that is regulated by neuropeptides. We have previously reported that after preexposure to the repulsive odor 2-nonanone, C. elegans migrates farther away from the odor source than the control animals do (Kimura et al., 2010). We have recently found that this farther migration by preexposure is likely regulated by branched pathways that regulate the duration of straight migration ("run"), depending on the run direction. When the animals are migrating down the putative odor gradient within 60°, they keep running to that direction. In contrast, when the animals are migrating down the gradient over 60°, they stop running and start turning to change their migratory direction. Interestingly, after preexposure to the odor, the animals increase the run duration only when the run direction is within 60°. Computer simulation shows that this direction-selective increase in the run duration is sufficient to cause farther migration after the preexposure. We also found that the direction-selective increase in the run duration is specifically abolished by mutations in the 2 genes required for neuropeptide synthesis. Thus, our results suggest that direction-selective behavioral modulation is executed by branched neural pathways and that only 1 pathway is modulated by peptide signaling for efficient odor avoidance.	O1-8-2-4 ドーパミン・オクトパミンシグナル伝達は、非連合学習において侵害刺激受容ニューロンを制御する～線虫C. elegansをモデルとして Dopamine-octopamine layered signalings regulate nociceptive neurons during non-associative odor learning in the nematode C. elegans ○木村幸太郎1, 藤江由香子1, 山添萌子1, 谷本悠生1, 川添有哉1, 藤田幸輔1 ○Kotaro Kimura1, Yukako Fujie1, Akiko Yamazoe1, Yuki Tanimoto1, Yuya Kawazoe1, Kosuke Fujita1 阪大院・理・生物科学1 Dept Biological Sciences, Osaka Univ, Osaka1 In mammals, dopamine plays significant roles in regulating behavior, motivation and learning. However, the mechanisms by which dopamine regulates animal's neural functions have not been fully understood. Through molecular genetics and optophysiological analyses, we show that dopamine-octopamine layered signalings regulate nociceptive neurons during non-associative odor learning in the nematode C. elegans. Preexposure to repulsive odor 2-nonanone leads to enhancement of avoidance behavior to the odor as a type of non-associative learning, and this odor learning requires the D2-like dopamine receptor DOP-3 in RIC interneurons (Kimura et al, J. Neurosci., 2010). Recently we found that dopamine signaling in RIC neurons suppresses the release of octopamine, the invertebrate counterpart of noradrenaline, and octopamine then functions via the GPCR-type receptor SER-3 in ASH nociceptive neurons. Integrated optophysiological and behavioral analyses revealed that, in naive animals, ASH neurons are activated by temporal increment of the odor concentration, which is required to initiate course correction when the animals migrate to the wrong direction (i.e., up toward the repulsive odor source). We also found that the dopamine-octopamine layered signalings appeared to be required to maintain the ASH activity for course correction during the learning process. Interestingly, neuropeptide signaling is also required for the learning to increase migratory duration toward the proper direction (i.e., away from the odor source), likely in parallel with the dopamine-octopamine signalings (Yamazoe et al., this meeting). Taken together, our results demonstrate that different aspects of sensory behavior are regulated by multiple neuromodulators, even in simple non-associative learning.

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