title: Convergence of Lemniscal and Local Excitatory Inputs on Large GABAergic Tectothalamic Neurons.
abstract: Large GABAergic (LG) neurons form a distinct cell type in the inferior colliculus (IC), identified by the presence of dense VGLUT2-containing axosomatic terminals. Although some of the axosomatic terminals originate from local and commissural IC neurons, it has been unclear whether LG neurons also receive axosomatic inputs from the lower auditory brainstem nuclei, i.e., cochlear nuclei (CN), superior olivary complex (SOC), and nuclei of the lateral lemniscus (NLL). In this study we injected recombinant viral tracers that force infected cells to express GFP in a Golgi-like manner into the lower auditory brainstem nuclei to determine whether these nuclei directly innervate LG cell somata. Labeled axons from CN, SOC, and NLL terminated as excitatory axosomatic endings, identified by colabeling of GFP and VGLUT2, on single LG neurons in the IC. Each excitatory axon made only a few axosomatic contacts on each LG neuron. Inputs to a single LG cell are unlikely to be from a single brainstem nucleus, since lesions of individual nuclei failed to eliminate most VGLUT2-positive terminals on the LG neurons. The estimated number of inputs on a single LG cell body was almost proportional to the surface area of the cell body. Double injections of different viruses into IC and a brainstem nucleus showed that LG neurons received inputs from both. These results demonstrated that both ascending and intrinsic sources converge on the LG somata to control inhibitory tectothalamic projections.
authors: Department of Anatomy, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193, Japan.|Research and Education Program for Life Science, University of Fukui, Fukui, 910-8507, Japan.
authors: Tetsufumi
authors: T
authors: Ito
authors: Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan.
authors: Hiroyuki
authors: H
authors: Hioki
authors: Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan.|Research Fellow of Japan Society for the Promotion of Science (JSPS), 5-3-1 Koujimachi, Tokyo, 102-8472, Japan.
authors: Jaerin
authors: J
authors: Sohn
authors: Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan.
authors: Shinichiro
authors: S
authors: Okamoto
authors: Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan.
authors: Takeshi
authors: T
authors: Kaneko
authors: Department of Anatomy, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193, Japan.|Research and Education Program for Life Science, University of Fukui, Fukui, 910-8507, Japan.
authors: Satoshi
authors: S
authors: Iino
authors: Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut, 06030-3401, USA.
authors: Douglas L
authors: DL
authors: Oliver
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism; D048429:Cell Size; D005260:Female; D059330:GABAergic Neurons / Q000166:cytology* / Q000378:metabolism; D005968:Glutamate Decarboxylase / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007150:Immunohistochemistry; D007245:Inferior Colliculi / Q000166:cytology* / Q000378:metabolism; D008297:Male; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism; D056347:Neuroanatomical Tract-Tracing Techniques; D010784:Photomicrography; D020318:Rats, Long-Evans; D013569:Synapses / Q000378:metabolism; D003336:Tectum Mesencephali / Q000166:cytology / Q000378:metabolism; D013788:Thalamus / Q000166:cytology / Q000378:metabolism; D050599:Vesicular Glutamate Transport Protein 2 / Q000378:metabolism
chemical_list: C493475:Slc17a6 protein, rat; D050599:Vesicular Glutamate Transport Protein 2; D049452:Green Fluorescent Proteins; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1
keywords: GABA; RGD ID: 1566430; RRID: AB_2278725; RRID: AB_94856; RRID: AB_94966; auditory system; excitatory axosomatic synapse; inferior colliculus; vesicular glutamate transporter