title: Quantitative analysis of axon bouton distribution of subthalamic nucleus neurons in the rat by single neuron visualization with a viral vector.
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.
authors.affiliation: Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Koshimizu
authors.forename: Fumino
authors.initials: F
authors.lastname: Fujiyama
authors.forename: Kouichi C
authors.initials: KC
authors.lastname: Nakamura
authors.forename: Takahiro
authors.initials: T
authors.lastname: Furuta
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kaneko
mesh_terms: D000818:Animals; D001369:Axons / Q000648:ultrastructure*; D001479:Basal Ganglia / Q000166:cytology; D064026:Calbindins; D005822:Genetic Vectors / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D009474:Neurons / Q000166:cytology*; D017729:Presynaptic Terminals / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D012845:Sindbis Virus / Q000502:physiology; D020531:Subthalamic Nucleus / Q000166:cytology*; D050599:Vesicular Glutamate Transport Protein 2 / Q000378:metabolism
chemical_list: D064026:Calbindins; D064030:S100 Calcium Binding Protein G; D050599:Vesicular Glutamate Transport Protein 2; D049452:Green Fluorescent Proteins