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エルゼビア / NSR協賛シンポジウム:体性感覚:生体警告、運動制御、発達、自己意識のための基本感覚システム
Elsevier - NSR Sponsored Symposium:Somatosensory; Fundamental sensory system for bodily alert, motor control, development, and self-consciousness

開催日 2014/9/11
時間 14:00 - 16:00
会場 Room C(502)
Chairperson(s) 村田 哲 / Akira Murata (近畿大学医学部生理学 / Department of Physiology, Kinki University Faculty of Medicine, Japan)
内藤 栄一 / Eiichi Naito (独立行政法人 情報通信研究機構 脳情報通信融合研究センター / Center for Information and Neural Networks (CiNet), National Institute of Information and Communication Technology, Japan)

Large-scale somatotopic reorganization via remodeling of thalamic afferent synapses after peripheral sensory nerve injury

  • S1-C-2-3
  • 竹内 雄一 / Yuichi Takeuchi:1 宮田 麻理子 / Mariko Miyata:1 
  • 1:東京女子医科大学 医学部 第一生理学教室 / Dept of Physiol, School of Med, Tokyo Women's Med Univ, Tokyo, Japan 

Peripheral sensory nerve injury causes large-scale somatotopic reorganization in the brain. However, neural circuit mechanisms by which the reorganization occurs remain largely unknown. A relay neuron in the mouse whisker sensory thalamus (V2 VPm) receives generally a single afferent fiber originating from the whisker-representing trigeminal nucleus (PrV2). We here found that this one-to-one synaptic relationship was disrupted within one week after transection of the whisker sensory nerve: newly afferent fibers were recruited onto a relay neuron after the nerve transection. Multiply innervating afferent fibers consisted of two functionally distinct populations:'Strong' and 'Weak' fibers. A cluster analysis of EPSC properties suggested that the Weak fibers were putative newly recruited fibers. To reveal relationships between this synaptic remodeling and somatotopic reorganization, we then employed the Krox20-Ai14 transgenic mouse, in which PrV2-origin afferent fibers are specifically labeled with fluorescent protein. Using this mouse, we found that non-PrV2-origin afferent terminals significantly increased in the V2 VPm after the injury, whereas PrV2-origin afferent terminals decreased and weakened around the same time as the synaptic remodeling. Origins of non-PrV2-origin afferent fibers after the transection included the mandibular (V3) subregions of trigeminal nuclei and the dorsal column nuclei, which normally represent body parts other than whiskers. These results indicate that the transection of whisker sensory nerve induces considerable retraction of PrV2-origin afferent fibers and invasion of non-PrV2-origin ones in the V2 VPm, thereby induces large-scale somatotopic reorganization.

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