Differential calretinin interneuron morphology in the primary visual cortex versus the lateral prefrontal cortex in the monkey and mouse

Abstract

In the mammalian neocortex, GABAergic interneurons play a variety of roles in higher-order brain functions as key components of brain circuits. Many studies have revealed properties of pyramidal neurons, but the functions of interneurons are relatively poorly understood. Focusing on inter-species differences, previous work in our lab (Gilman et al, 2017) revealed pyramidal neuron differences in monkey and mouse primary visual (V1) and frontal (FC) cortices. Here, we designed a comparative study in a similar context to reveal knowledge of Calretinin (CR)-expressing interneurons in monkey and mouse V1 and area FA of the mouse, prefrontal cortical area 46, and V1 of the monkey. Monkey and mouse brain tissues were immuno-stained, scanned with a confocal microscope and 3D reconstructed using NeuroLucida 360. Semi-automated analyses revealed that mouse CR interneurons on both brain regions were larger and showed more dendritic branching. Cell type sorting following the previous classification method by Cauli et al (2014) showed distinctive cell type distribution Monkey V1. CR interneurons in V1 regions in both species showed features that differentiate them from FC interneurons, including more node counts than those in FC. Also, a sudden increase in average V1 dendritic diameter after its 75% length progression was shown between species. These findings have provided gap-filling knowledge about CR+ interneuron species-specific differences in V1 and PFC, which gives a foundation for inter-species data comparison.