Early postnatal development of pyramidal neurons across layers of the mouse medial prefrontal cortex

Tim Kroon,Rhiannon M Meredith,Lola Van Linge,Eline Van Hugte,Huibert D Mansvelder

doi:10.1038/s41598-019-41661-9

Abstract

Mammalian neocortex is a highly layered structure. Each layer is populated by distinct subtypes of principal cells that are born at different times during development. While the differences between principal cells across layers have been extensively studied, it is not known how the developmental profiles of neurons in different layers compare. Here, we provide a detailed morphological and functional characterisation of pyramidal neurons in mouse mPFC during the first postnatal month, corresponding to known critical periods for synapse and neuron formation in mouse sensory neocortex. Our data demonstrate similar maturation profiles of dendritic morphology and intrinsic properties of pyramidal neurons in both deep and superficial layers. In contrast, the balance of synaptic excitation and inhibition differs in a layer-specific pattern from one to four postnatal weeks of age. Our characterisation of the early development and maturation of pyramidal neurons in mouse mPFC not only demonstrates a comparable time course of postnatal maturation to that in other neocortical circuits, but also implies that consideration of layer- and time-specific changes in pyramidal neurons may be relevant for studies in mouse models of neuropsychiatric and neurodevelopmental disorders.

Highlights

Pyramidal neurons (PNs) in different cortical layers differ in their expression of molecular markers[1,2,3], responses to sensory stimuli[4], patterns of synaptic connectivity[5], and morphological properties[6,7,8,9]
We know very little about laminar differences in the development of intrinsic neuronal characteristics like dendritic morphology and membrane properties, because the majority of studies investigating layer specificity have focused on neuronal differences at one particular stage of cortical development[14,15]
We provide an extensive analysis of the development of dendritic morphology and intrinsic membrane properties of pyramidal neurons in layers 3 and 5 of the mouse medial prefrontal cortex (mPFC), as well as their synaptic input

Summary

Introduction

Pyramidal neurons (PNs) in different cortical layers differ in their expression of molecular markers[1,2,3], responses to sensory stimuli[4], patterns of synaptic connectivity[5], and morphological properties[6,7,8,9]. We know very little about laminar differences in the development of intrinsic neuronal characteristics like dendritic morphology and membrane properties, because the majority of studies investigating layer specificity have focused on neuronal differences at one particular stage of cortical development[14,15]. Development of synaptic input follows a markedly different time course in either layer We suggest that this could result in unique sensitive time windows for synaptic maturation of individual cortical layers in the mouse mPFC

Methods

Results

Conclusion