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Perisomatic‐targeting granule cells in the mouse olfactory bulb
Author(s) -
Naritsuka Hiromi,
Sakai Kazuhisa,
Hashikawa Tsutomu,
Mori Kensaku,
Yamaguchi Masahiro
Publication year - 2009
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.22063
Subject(s) - biology , olfactory bulb , granule cell , inhibitory postsynaptic potential , neuroscience , interneuron , cell type , microbiology and biotechnology , neocortex , hippocampal formation , dentate gyrus , cell , central nervous system , genetics
Abstract Inhibitory interneurons in the hippocampus and neocortex are differentiated into several morphological and functional subtypes that innervate distinct subcellular domains of principal neurons. In the olfactory bulb (OB), odor information is processed by local neuronal circuits that include the major inhibitory interneuron, granule cells (GCs). All GCs reported to date target their inhibitory output synapses mainly to dendrites of mitral cells (MCs) and tufted cells (TCs) in the external plexiform layer (EPL). Here we identified a novel type of GC that targets output synapses selectively to the perisomatic region of MCs. In the OB of adult transgenic mice expressing green fluorescent protein (GFP) under the control of nestin gene regulatory regions, we observed cells in the granule cell layer (GCL) that have GC‐like morphology and strongly express GFP (referred to as type S cells). Type S cells expressed NeuN and GAD67, molecular markers for GCs. Intracellular labeling of type S cells revealed that their dendrites did not enter the EPL, but formed branches and spines within the GCL, internal plexiform layer, and mitral cell layer. Type S cells typically had huge spines at the ends of the apical dendrites. Some of the terminal spines attached to the perisomatic region of MCs and formed dendrosomatic reciprocal synapses with a presumed granule‐to‐mitral inhibitory synapse and a mitral‐to‐granule excitatory synapse. These findings indicate the morphological differentiation of GCs into dendritic‐targeting and perisomatic‐targeting subsets, and suggest the functional differentiation of the GC subsets in the processing of odor information in the OB. J. Comp. Neurol. 515:409–426, 2009. © 2009 Wiley‐Liss, Inc.