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-->   Takeshi Imai Last modified date：2024.05.05 Professor / Department of Basic Medicine Faculty of Medical Sciences 1 Research Interests 2 Academic Activities 2.1 Papers 2.2 Reports 3 Membership in Academic Society 4 Awards Graduate School Department of Medical Sciences Graduate School of Medical Sciences Undergraduate School Department of Biomedical Science School of Medicine Department of Medicine School of Medicine Other Organization Research and Development Center for Five-Sense Devices Research Center for Human Disease Modeling E-Mail　*Since the e-mail address is not displayed in Internet Explorer, please use another web browser:Google Chrome, safari. Homepage https://kyushu-u.elsevierpure.com/en/persons/takeshi-imai　Reseacher Profiling Tool　Kyushu University Pure https://www.lab.med.kyushu-u.ac.jp/dn/Department of Developmental Neurophysiology . http://researchmap.jp/takeshi.imai/?lang=englishResearchmap . https://scholar.google.com/citations?sortby=pubdate&hl=en&user=VPwm0QUAAAAJ&view_op=list_worksGoogle Scholar . https://sites.google.com/site/seedbresources/SeeDB Resources . Academic Degree Ph.D. Country of degree conferring institution (Overseas) No Field of Specialization Neuroscience Total Priod of education and research career in the foreign country 00years00months Research Research Interests Neurosciencekeyword : Neuronal circuit formation, Olfaction2017.04～2017.04. Academic Activities Reports  Show All Reports >> Papers  Show All Papers >> 1. Satoshi Fujimoto, Marcus N Leiwe, Shuhei Aihara, Richi Sakaguchi, Yuko Muroyama, Reiko Kobayakawa, Ko Kobayakawa, Tetsuichiro Saito, Takeshi Imai, Activity-dependent local protection and lateral inhibition control synaptic competition in developing mitral cells in mice., Developmental cell, 10.1016/j.devcel.2023.05.004, 2023.05, In developing brains, activity-dependent remodeling facilitates the formation of precise neuronal connectivity. Synaptic competition is known to facilitate synapse elimination; however, it has remained unknown how different synapses compete with one another within a post-synaptic cell. Here, we investigate how a mitral cell in the mouse olfactory bulb prunes all but one primary dendrite during the developmental remodeling process. We find that spontaneous activity generated within the olfactory bulb is essential. We show that strong glutamatergic inputs to one dendrite trigger branch-specific changes in RhoA activity to facilitate the pruning of the remaining dendrites: NMDAR-dependent local signals suppress RhoA to protect it from pruning; however, the subsequent neuronal depolarization induces neuron-wide activation of RhoA to prune non-protected dendrites. NMDAR-RhoA signals are also essential for the synaptic competition in the mouse barrel cortex. Our results demonstrate a general principle whereby activity-dependent lateral inhibition across synapses establishes a discrete receptive field of a neuron.. 2. Aihara S, Fujimoto S, Sakaguchi R, Imai T., BMPR-2 gates activity-dependent stabilization of primary dendrites during mitral cell remodeling, Cell Reports, https://doi.org/10.1016/j.celrep.2021.109276, 12, 22, 109276, 2021.06, Developing neurons initially form excessive neurites and then remodel them based on molecular cues and neuronal activity. Developing mitral cells in the olfactory bulb initially extend multiple primary dendrites. They then stabilize single primary dendrites while eliminating others. However, the mechanisms underlying selective dendrite remodeling remain elusive. Using CRISPR-Cas9-based knockout screening combined with in utero electroporation, we identify BMPR-2 as a key regulator for selective dendrite stabilization. Bmpr2 knockout and its rescue experiments show that BMPR-2 inhibits LIMK without ligands and thereby permits dendrite destabilization. In contrast, the overexpression of antagonists and agonists indicates that ligand-bound BMPR-2 stabilizes dendrites, most likely by releasing LIMK. Using genetic and FRET imaging experiments, we demonstrate that free LIMK is activated by NMDARs via Rac1, facilitating dendrite stabilization through F-actin formation. Thus, the selective stabilization of primary dendrites is ensured by concomitant inputs of BMP ligands and neuronal activity.. 3. Inagaki S, Iwata R, Iwamoto M, Imai T., Widespread inhibition, antagonism, and synergy in mouse olfactory sensory neurons in vivo, Cell Reports, https://doi.org/10.1016/j.celrep.2020.107814, 13, 107814, 107814, 2020.06, Sensory information is selectively or non-selectively enhanced and inhibited in the brain, but it remains unclear whether and how this occurs at the most peripheral level. Using in vivo calcium imaging of mouse olfactory bulb and olfactory epithelium in wild-type and mutant animals, we show that odors produce not only excitatory but also inhibitory responses in olfactory sensory neurons (OSNs). Heterologous assays indicate that odorants can act as agonists to some but inverse agonists to other odorant receptors. We also demonstrate that responses to odor mixtures are extensively suppressed or enhanced in OSNs. When high concentrations of odors are mixed, widespread antagonism suppresses the overall response amplitudes and density. In contrast, a mixture of low concentrations of odors often produces synergistic effects and boosts the faint odor inputs. Thus, odor responses are extensively tuned by inhibition, antagonism, and synergy at the most peripheral level, contributing to robust sensory representations.. 4. Richi Sakaguchi, Marcus N. Leiwe, Takeshi Imai, Bright multicolor labeling of neuronal circuits with fluorescent proteins and chemical tags, ELIFE, 10.7554/eLife.40350, 7, 2018.11, The stochastic multicolor labeling method 'Brainbow' is a powerful strategy to label multiple neurons differentially with fluorescent proteins; however, the fluorescence levels provided by the original attempts to use this strategy were inadequate. In the present study, we developed a stochastic multicolor labeling method with enhanced expression levels that uses a tetracycline-operator system (Tetbow). We optimized Tetbow for either plasmid or virus vector-mediated multicolor labeling. When combined with tissue clearing, Tetbow was powerful enough to visualize the three-dimensional architecture of individual neurons. Using Tetbow, we were able to visualize the axonal projection patterns of individual mitral/tufted cells along several millimeters in the mouse olfactory system. We also developed a Tetbow system with chemical tags, in which genetically encoded chemical tags were labeled with synthetic fluorophores. This was useful in expanding the repertoire of the fluorescence labels and the applications of the Tetbow system. Together, these new tools facilitate light-microscopy-based neuronal tracing at both a large scale and a high resolution.. 5. Ryo Iwata, Hiroshi Kiyonari, Takeshi Imai, Mechanosensory-Based Phase Coding of Odor Identity in the Olfactory Bulb, Neuron, 10.1016/j.neuron.2017.11.008, 96, 5, 1139-1152.e7, 2017.12, Mitral and tufted (M/T) cells in the olfactory bulb produce rich temporal patterns of activity in response to different odors. However, it remains unknown how these temporal patterns are generated and how they are utilized in olfaction. Here we show that temporal patterning effectively discriminates between the two sensory modalities detected by olfactory sensory neurons (OSNs): odor and airflow-driven mechanical signals. Sniff-induced mechanosensation generates glomerulus-specific oscillatory activity in M/T cells, whose phase was invariant across airflow speed. In contrast, odor stimulation caused phase shifts (phase coding). We also found that odor-evoked phase shifts are concentration invariant and stable across multiple sniff cycles, contrary to the labile nature of rate coding. The loss of oscillatory mechanosensation impaired the precision and stability of phase coding, demonstrating its role in olfaction. We propose that phase, not rate, coding is a robust encoding strategy of odor identity and is ensured by airflow-induced mechanosensation in OSNs. Iwata et al. demonstrate that phase coding, but not rate coding, in mitral cells is useful for concentration-invariant odor identity coding. They also found that mechanosensation in olfactory sensory neurons facilitates, rather than masks, the robust phase coding of odors.. Membership in Academic Society THE JAPAN NEUROSCIENCE SOCIETY JAPANESE SOCIETY OF DEVELOPMENTAL BIOLOGISTS Society for Neuroscience The physiological society of Japan Awards Nakatani Award Incentive Prize Unauthorized reprint of the contents of this database is prohibited. Copyright © 2006, Kyushu University. All rights reserved.