title: Unusual patch-matrix organization in the retrosplenial cortex of the reeler mouse and Shaking rat Kawasaki.
abstract: The rat granular retrosplenial cortex (GRS) is a simplified cortex, with distinct stratification and, in the uppermost layers, distinct modularity. Thalamic and cortical inputs are segregated by layers and in layer 1 colocalize, respectively, with apical dendritic bundles originating from neurons in layers 2 or 5. To further investigate this organization, we turned to reelin-deficient reeler mouse and Shaking rat Kawasaki. We found that the disrupted lamination, evident in Nissl stains in these rodents, is in fact a patch-matrix mosaic of segregated afferents and dendrites. Patches consist of thalamocortical connections, visualized by vesicular glutamate transporter 2 (VGluT2) or AChE. The surrounding matrix consists of corticocortical terminations, visualized by VGluT1 or zinc. Dendrites concentrate in the matrix or patches, depending on whether they are OCAM positive (matrix) or negative (patches). In wild-type rodents and, presumably, mutants, OCAM(+) structures originate from layer 5 neurons. By double labeling for dendrites (filled by Lucifer yellow in fixed slice) and OCAM immunofluorescence, we ascertained 2 populations in reeler: dendritic branches either preferred (putative layer 5 neurons) or avoided (putative supragranular neurons) the OCAM(+) matrix. We conclude that input-target relationships are largely preserved in the mutant GRS and that dendrite-dendrite interactions involving OCAM influence the formation of the mosaic configuration.
authors.affiliation: Laboratory for Cortical Organization and Systematics, RIKEN, Brain Science Institute, Wako, Saitama 351-0198, Japan.
authors.forename: Noritaka
authors.initials: N
authors.lastname: Ichinohe
authors.forename: Adrian
authors.initials: A
authors.lastname: Knight
authors.forename: Masaharu
authors.initials: M
authors.lastname: Ogawa
authors.forename: Toshio
authors.initials: T
authors.lastname: Ohshima
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Mikoshiba
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Yoshihara
authors.forename: Toshio
authors.initials: T
authors.lastname: Terashima
authors.forename: Kathleen S
authors.initials: KS
authors.lastname: Rockland
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics*; D002540:Cerebral Cortex / Q000473:pathology*; D003712:Dendrites / Q000473:pathology*; D018690:Excitatory Amino Acid Agonists; D016326:Extracellular Matrix Proteins / Q000235:genetics*; D005260:Female; D007051:Ibotenic Acid; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008818:Mice, Neurologic Mutants / Q000033:anatomy & histology*; D016253:Microscopy, Immunoelectron; D009419:Nerve Tissue Proteins / Q000235:genetics*; D019006:Neural Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism; D009434:Neural Pathways; D017966:Pyramidal Cells / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D051381:Rats; D011922:Rats, Mutant Strains; D017208:Rats, Wistar; D000091042:Reelin Protein; D012697:Serine Endopeptidases / Q000235:genetics*; D013788:Thalamus / Q000473:pathology*; D050598:Vesicular Glutamate Transport Protein 1 / Q000378:metabolism; D050599:Vesicular Glutamate Transport Protein 2 / Q000378:metabolism
chemical_list: D015816:Cell Adhesion Molecules, Neuronal; D018690:Excitatory Amino Acid Agonists; D016326:Extracellular Matrix Proteins; C108768:Ncam2 protein, mouse; D009419:Nerve Tissue Proteins; D019006:Neural Cell Adhesion Molecules; D000091042:Reelin Protein; C000717129:Reln protein, rat; C493477:Slc17a6 protein, mouse; C493475:Slc17a6 protein, rat; C493465:Slc17a7 protein, mouse; C493466:Slc17a7 protein, rat; D050598:Vesicular Glutamate Transport Protein 1; D050599:Vesicular Glutamate Transport Protein 2; D007051:Ibotenic Acid; D000110:Acetylcholinesterase; C000717128:Reln protein, mouse; D012697:Serine Endopeptidases