小脳 Cerebellum
O1-8-6-1 マウス小脳皮質におけるaldolase C発現領域に相関した同期性の高い登上線維応答 Synchronous climbing fiber responses correlated with the aldolase C compartments in mouse cerebellar cortex ○堤新一郎1, 多田真弓1, 崎村建司2, 喜多村和郎1, 狩野方伸1 ○Shinichiro Tsutsumi1, Mayumi Tada1, Kenji Sakimura2, Kazuo Kitamura1, Masanobu Kano1 東京大院・医・神経生理1, 新潟大・脳研2 Dept NeuroPhysiol, Univ of Tokyo, Tokyo1, Brain Res Inst, Niigata Univ2 The cerebellar cortex has an elaborate zonal organization extending rostro-caudally. Purkinje cells (PCs) located in these parasagittal stripes show synchronous complex spike (CS) activities. This functional structure is considered to arise from the anatomical organization of olivocerebellar projection and the electrical coupling among neurons in the inferior olive. The longitudinal compartments of aldolase C expression has been shown to correlate with anatomical climbing fiber innervation of PCs (Sugihara et al., 2001) and functional CS synchrony at the resolution of several hundred micrometers (Sugihara et al., 2007). To elucidate the relationship between the CS synchrony and the aldolase C compartments at higher resolution, we performed two-photon calcium imaging in anesthetized mice that express fluorescent protein in their aldolase C-expressing PCs. We found a highly precise correlation between the CS synchrony and the aldolase C compartments. Spontaneous CS activities within aldolase C positive-PCs and those within aldolase C negative-PCs were both highly synchronized, and the border of high synchrony areas precisely corresponded to that of the aldolase C compartments at single cell resolution. We further investigated the relationship between aldolase C compartments and functional microzones identified by the responses to sensory stimuli. Fine microzonal structures containing several PCs nearby could be activated in response to perioral air puff stimulation. The border of aldolase C compartments corresponded to that of functional microzones. These results suggest that CS synchrony precisely reflects CF innervation and the electrical coupling in the inferior olive, and that each aldolase C compartment represents distinct functional unit in the cerebellar cortex.	O1-8-6-2 下オリーブ核ネットワークにおける結合強度の適応変化が小脳学習へもたらす効果について Effect of adaptive coupling of a network of inferior olive neurons on cerebellar learning ○徳田功1, 川人光男3 ○Isao Tokuda1, Huu Hoang1, Nicolas Schweighofer2, Mitsuo Kawato3 立命館大学　理工学部　機械工学科1, 南カリフォルニア大学2, 国際電気通信基礎技術研究所3 Dept Mech Eng, Ritsumeikan Univ, Kusatsu1, Biokinesiology and Physical Therapy, Uni of Southern California, Los Angeles2, ATR Computational Neuroscience Laboratories, Kyoto3 Intensive research on neurophysiology and theoretical modeling of the cerebellum paved the way for the establishment of the basics of the cerebellar learning. In the cerebellar learning hypothesis, inferior olive neurons are presumed to transmit high fidelity error signals, despite their low firing rates. The idea of chaotic resonance has been proposed to realize efficient error transmission by desynchronized spiking activities induced by moderate electrical coupling between inferior olive neurons. A recent study suggests that the coupling strength between inferior olive neurons can be adaptive and may decrease during the learning process. We show that such a decrease in coupling strength can be beneficial for motor learning, since efficient coupling strength depends upon the magnitude of the error signals. We introduce a scheme of adaptive coupling that enhances the learning of a neural controller for fast arm movements. Our numerial study supports the view that the controlling strategy of the coupling strength provides an additional degree of freedom to optimize the actual learning in the cerebellum.
O1-8-6-3 オーファン受容体GPRC5Bノックアウトマウスは小脳プルキンエ細胞の軸索変性によりその運動協調・学習機能が障害される GPRC5B KO mice are induced axon degeneration in cerebellar Purkinje neurons, resulting in impaired motor coordination and learning ○木下雅美1 , 佐野孝光1,2, 大嶋恵理子1, 清水知佳1, 濱裕1, 遠山稿二郎3, 立川哲也1鈴木寿紀1, 山田一之1, 宮脇敦1, 永尾総一1, 平林義雄1 ○Masami Kinoshita1 , Takamitsu Sano1,2, Eriko Ooshima1, Chika Shimizu1, Hiroshi Hama1, Koujiro Tohyama3, Tetsuya Tatsukawa1, Dinh Tung Le1, Toshinori Suzuki1, Kazuyuki Yamada1, Atsushi Miyawaki1, Souichi Nagao11, Yoshio Hirabayashi1 理化学研究所　脳科学総合研究センター1, 北海道大学2, 岩手医科大学3 RIKEN BSI, Wako, Japan1, Hokkaido Univ, Sapporo, Japan2, Iwate Med University, Morioka, Japan3 GPRC5B is an orphan G protein-coupled receptor (GPCR) membrane protein and is also the mammalian ortholog of Drosophila BOSS (Bride of sevenless) involved in regulation of systemic sugar and lipid metabolism as well as eye differentiation. We recently found so-far-unrecognized axon degeneration of Purkinje neurons in the GPRC5B KO mice, accompanied by extremely swollen axon terminals and accumulation of organelles such as mitochondrion or smooth endoplasmic reticulum. Our comprehensive behavioral tests clearly demonstrated impaired motor coordination and learning of the GPRC5B KO mice, especially characteristic of a distinct lack of long-term motor learning. Also we detected incomplete synaptogenesis between the GPRC5B-deficient Purkinje neurons and the deep cerebellar nuclear (DCN) neruons. Regardless of pathological manifestations, however, the GPRC5B-deficient Purkinje neurons can survive for life and also present no abnormalities in LTD and other electrophysiological properties currently. These data provide evidene of that the GPRC5B deficiency of Purkinje neuron is likely to disturb physiological homeostasis in the axon, thereby inducing the impaired motor coordination and learning in the mutant mice.	O1-8-6-4 軸索投射パタンとゼブリンコンパートメント縦区画の発達過程が小脳の前部と後部の機能的関連の基盤を提供する Axonal projection patterns and the developmental history of the longitudinal compartments provide a basis for the functional linking of rostral and caudal cerebellar regions ○杉原泉1, 藤田啓史1,2 ○Izumi Sugihara1, Hirofumi Fujita1,2 東京医科歯科大学　医歯学総合研究科　システム神経生理学分野1, ソーク研究所システム神経生物学研究室2 Dept Systems Neurophysiol, Tokyo Med & Dental Univ, Bunkyo-ku, Tokyo, Japan1, Systems Neurobiology Laboratories, The Salk Institute for Biological Studies, La Jolla, CA, USA2 The cerebellum has mirror-imaged somatotopic double representation of the body in the rostral and caudal pars intermedia. However, how the projection patterns of afferent axons (mossy fiber axons and olivocerebellar (OC) climbing fiber axons) are related to the double representation has not been well understood. To clarify the relationship between the projection patterns of OC axons and specific cerebellar lobules, we re-analyzed our previous data on reconstructed single OC axons. Single OC axons often gave rise to longitudinal branches that terminated in longitudinal zebrin compartments in separate lobules. Combinations of lobules that were specifically innervated by the longitudinal branches (lobule V-simple lobule and crus II-paramedian lobule in the pars intermedia and hemisphere, and lobules I-V and lobule VIII in the vermis) fit with the areas of rostrocaudal double representation. To further clarify the linking between these areas, we re-examined our recent data on compartmental development of the cerebellum at and after embryonic day 17.5 (E17.5), when the immature OC projection is formed. A group of OC axons that expressed EphA4 innervated a clustered Purkinje cell subset in the pars intermedia at E17.5. Subsequently at postnatal day 1 (P1), this Purkinje cell cluster and trajectories of the EphA4-expressing OC axons were split rostrocaudally across crus I. This suggests that the split clusters are the origin of specific combination of the Purkinje cell subsets (longitudinal zebrin compartments) in separate rostral and caudal lobules that are innervated by longitudinal branches of OC axons across crus I. Taken together, we propose that the longitudinal split of Purkinje cell clusters during cerebellar development is a basis of longitudinal branching of OC axons, which then provides a basis for the functional linking between the rostral and caudal cerebellum including the mirror-imaged somatotopic double representation of the body.

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