Distribution and structure of synapses on medial vestibular nuclear neurons targeted by cerebellar flocculus purkinje cells and vestibular nerve in mice: Light and electron microscopy studies

Matsuno, Hitomi and Kudoh, Moeko and Watakabe, Akiya and Yamamori, Tetsuo and Shigemoto, Ryuichi and Nagao, Soichi (2016) Distribution and structure of synapses on medial vestibular nuclear neurons targeted by cerebellar flocculus purkinje cells and vestibular nerve in mice: Light and electron microscopy studies. PLoS One, 11 (10). Article number: e0164037 . ISSN 1932-6203

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Abstract

Adaptations of vestibulo-ocular and optokinetic response eye movements have been studied as an experimental model of cerebellum-dependent motor learning. Several previous physiological and pharmacological studies have consistently suggested that the cerebellar flocculus (FL) Purkinje cells (P-cells) and the medial vestibular nucleus (MVN) neurons targeted by FL (FL-targeted MVN neurons) may respectively maintain the memory traces of short- and long-term adaptation. To study the basic structures of the FL-MVN synapses by light microscopy (LM) and electron microscopy (EM), we injected green florescence protein (GFP)-expressing lentivirus into FL to anterogradely label the FL P-cell axons in C57BL/6J mice. The FL P-cell axonal boutons were distributed in the magnocellular MVN and in the border region of parvocellular MVN and prepositus hypoglossi (PrH). In the magnocellular MVN, the FL-P cell axons mainly terminated on somata and proximal dendrites. On the other hand, in the parvocellular MVN/PrH, the FL P-cell axonal synaptic boutons mainly terminated on the relatively small-diameter (< 1 μm) distal dendrites of MVN neurons, forming symmetrical synapses. The majority of such parvocellular MVN/PrH neurons were determined to be glutamatergic by immunocytochemistry and in-situ hybridization of GFP expressing transgenic mice. To further examine the spatial relationship between the synapses of FL P-cells and those of vestibular nerve on the neurons of the parvocellular MVN/ PrH, we added injections of biotinylated dextran amine into the semicircular canal and anterogradely labeled vestibular nerve axons in some mice. The MVN dendrites receiving the FL P-cell axonal synaptic boutons often closely apposed vestibular nerve synaptic boutons in both LM and EM studies. Such a partial overlap of synaptic boutons of FL P-cell axons with those of vestibular nerve axons in the distal dendrites of MVN neurons suggests that inhibitory synapses of FL P-cells may influence the function of neighboring excitatory synapses of vestibular nerve in the parvocellular MVN/PrH neurons.

Item Type: Article
DOI: 10.1371/journal.pone.0164037
Subjects: 500 Science > 570 Life sciences; biology
500 Science > 570 Life sciences; biology > 571 Physiology
Research Group: Shigemoto Group
SWORD Depositor: Sword Import User
Depositing User: Sword Import User
Date Deposited: 05 Dec 2016 14:41
Last Modified: 05 Sep 2017 09:27
URI: https://repository.ist.ac.at/id/eprint/689

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