Structural development and dorsoventral maturation of the medial entorhinal cortex
Abstract
We investigated the structural development of superficial-layers of medial entorhinal cortex and parasubiculum in rats. The grid-layout and cholinergic-innervation of calbindin-positive pyramidal-cells in layer-2 emerged around birth while reelin-positive stellate-cells were scattered throughout development. Layer-3 and parasubiculum neurons had a transient calbindin-expression, which declined with age. Early postnatally, layer-2 pyramidal but not stellate-cells co-localized with doublecortin- a marker of immature neurons- suggesting delayed functional-maturation of pyramidal-cells. Three observations indicated a dorsal-to-ventral maturation of entorhinal cortex and parasubiculum: (i) calbindin-expression in layer-3 neurons decreased progressively from dorsal-to-ventral, (ii) doublecortin in layer-2 calbindin-positive-patches disappeared dorsally before ventrally, and (iii) wolframin-expression emerged earlier in dorsal than ventral parasubiculum. The early appearance of calbindin-pyramidal grid-organization in layer-2 suggests that this pattern is instructed by genetic information rather than experience. Superficial-layer-microcircuits mature earlier in dorsal entorhinal cortex, where small spatial-scales are represented. Maturation of ventral-entorhinal-microcircuits- representing larger spatial-scales - follows later around the onset of exploratory behavior.
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Ethics
Animal experimentation: All experimental procedures were performed according to the German guidelines on animal welfare under the supervision of local ethics committees (LaGeSo) under the permit T0106 - 14.
Reviewing Editor
- Howard Eichenbaum, Boston University, United States
Version history
- Received: November 26, 2015
- Accepted: March 27, 2016
- Accepted Manuscript published: April 2, 2016 (version 1)
- Accepted Manuscript updated: April 7, 2016 (version 2)
- Version of Record published: April 22, 2016 (version 3)
Copyright
© 2016, Ray & Brecht
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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