Comparative Analysis of Layer-Specific Genes in Mammalian Neocortex

Abstract

We examined the expression patterns of 4 layer-specific genes in monkey and mouse cortices by fluorescence double in situ hybridization. Based on their coexpression profiles, we were able to distinguish several subpopulations of deep layer neurons. One group was characterized by the expression of ER81 and the lack of Nurr1 mRNAs and mainly localized to layer 5. In monkeys, this neuronal group was further subdivided by 5-HT2C receptor mRNA expression. The 5-HT2C(+)/ER81(+) neurons were located in layer 5B in most cortical areas, but they intruded layer 6 in the primary visual area (V1). Another group of neurons, in monkey layer 6, was characterized by Nurr1 mRNA expression and was further subdivided as Nurr1(+)/connective tissue growth factor (CTGF)(-) and Nurr1(+)/CTGF(+) neurons in layers 6A and 6B, respectively. The Nurr1(+)/CTGF(+) neurons coexpressed ER81 mRNA in monkeys but not in mice. On the basis of tracer injections in 3 monkeys, we found that the Nurr1(+) neurons in layer 6A send some corticocortical, but not corticopulvinar, projections. Although the Nurr1(+)/CTGF(-) neurons were restricted to lateral regions in the mouse cortex, they were present throughout the monkey cortex. Thus, an architectonic heterogeneity across areas and species was revealed for the neuronal subpopulations with distinct gene expression profiles.

Subplate in the developing cortex of mouse and human

“…Studies in our laboratory and those of other investigators have shown that these two genes are preferentially expressed in the subplate in rodents and nonhuman primates (Arimatsu et al 2003;Watakabe et al 2007;Hoerder-Suabedissen et al 2009). …”

Serotonin Modulates Fast-Spiking Interneuron and Synchronous Activity in the Rat Prefrontal Cortex through 5-HT1Aand 5-HT2AReceptors

“…Double and triple ISH experiments were performed following protocols described previously (Watakabe et al, 2007). An example of the procedure used to quantify double-labeled cells is shown in supplemental Figure S1 (available at www.jneurosci.org as supplemental material).…”

Comparative Anatomy of Marmoset and Mouse Cortex from Genomic Expression

“…Another comparative gene expression analysis in adult mouse and marmoset brain using microarray analysis did not report major differences (Datson et al, 2009). However, studies comparing gene expression in postnatal monkey and mouse brain identified multiple expression differences in gene expression within cortical layers and cell populations (Takahata et al, 2006(Takahata et al, , 2009Watakabe et al, 2006Watakabe et al, , 2007. Therefore, to find species-specific gene expression, it is important to analyze gene expression at the cellular level in specific regions for higher cognitive functions with high resolution in situ hybridization approaches.…”

“…The most commonly used "primate model species" for studying brain anatomy and behavior are Old World monkeys, typically rhesus monkeys (Macaca mulatta), and long-tailed (Macaca fascicularis) macaques because of resource availability and historical descriptions of these species (Rakic, 1988;Takahata et al, 2006Takahata et al, , 2009Watakabe et al, 2006Watakabe et al, , 2007. However, the disadvantages of using such monkeys for experimental manipulations include their large body size, inefficient fertility, and slow development to sexual maturity.…”