Quantitative analysis of axon bouton distribution of subthalamic nucleus neurons in the rat by single neuron visualization with a viral vector

Authors

  • Yoshinori Koshimizu,

    1. Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
    2. Core Research for Evolutionary Science and Technology, Japan Science and Technology Agency, Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan
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  • Fumino Fujiyama,

    1. Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
    2. Core Research for Evolutionary Science and Technology, Japan Science and Technology Agency, Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan
    Current affiliation:
    1. Laboratory of Neural Circuitry, Graduate School of Brain Science, Doshisha University, Kaifu-kan, Kansai Science City Campus, 4-1-1 Kizugawadai, Kizugawa City, Kyoto 619-0225, Japan
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  • Kouichi C. Nakamura,

    1. Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
    Current affiliation:
    1. Medical Research Council Anatomical Neuropharmacology Unit, Oxford OX1 3TH, UK
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  • Takahiro Furuta,

    1. Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
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  • Takeshi Kaneko

    Corresponding author
    1. Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
    • Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
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Abstract

The subthalamic nucleus (STN) of the basal ganglia plays a key role in motor control, and STN efferents are known to mainly target the external segment of the globus pallidus (GPe), entopeduncular nucleus (Ep), and substantia nigra (SN) with some axon collaterals to the other regions. However, it remains to be clarified how each STN neuron projects axon fibers and collaterals to those target nuclei of the STN. Here we visualized the whole axonal arborization of single STN neurons in the rat brain by using a viral vector expressing membrane-targeted green fluorescent protein, and examined the distribution of axon boutons in those target nuclei. The vast majority (8–9) of 10 reconstructed STN neurons projected to the GPe, SN, caudate-putamen (CPu), and Ep, which received, on average ± SD, 457 ± 425, 400 ± 347, 126 ± 143, and 106 ± 100 axon boutons per STN neuron, respectively. Furthermore, the density of axon boutons in the GPe was highest among these nuclei. Although these target nuclei were divided into calbindin-rich and -poor portions, STN projection showed no exclusive preference for those portions. Since STN neurons mainly projected not only to the GPe, SN, and Ep but also to the CPu, the subthalamostriatal projection might serve as a positive feedback path for the striato-GPe-subthalamic disinhibitory pathway, or work as another route of cortical inputs to the striatum through the corticosubthalamostriatal disynaptic excitatory pathway. J. Comp. Neurol. 521:2125–2146, 2013. © 2012 Wiley Periodicals, Inc.

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