Distribution Patterns of Subgroups of Inhibitory Neurons Divided by Calbindin 1

The inhibitory neurons in the brain play an essential role in neural network firing patterns by releasing γ-aminobutyric acid (GABA) as the neurotransmitter. In the mouse brain, based on the protein molecular markers, inhibitory neurons are usually to be divided into three non-overlapping groups: parvalbumin (PV), neuropeptide somatostatin (SST), and vasoactive intestinal peptide (VIP)-expressing neurons. Each neuronal group exhibited unique properties in molecule, electrophysiology, circuitry, and function. Calbindin 1 (Calb1), a ubiquitous calcium-binding protein, often acts as a "divider" in excitatory neuronal classification. Based on Calb1 expression, the excitatory neurons from the same brain region can be classified into two subgroups with distinct properties. Besides excitatory neurons, Calb1 also expresses in part of inhibitory neurons. But, to date, little research focused on the intersectional relationship between inhibitory neuronal subtypes and Calb1. In this study, we genetically targeted Calb1-expression (Calb1+) and Calb1-lacking (Calb1-) subgroups of PV and SST neurons throughout the mouse brain by flexibly crossing transgenic mice relying on multi-recombinant systems, and the distribution patterns and electrophysiological properties of each subgroup were further demonstrated. Thus, this study provided novel insights and strategies into inhibitory neuronal classification.

Quantitative analysis of the Golgi impregnated human (neo)striatal neurons: Observation of the morphological characteristics followed by an emphasis on the functional diversity of cells

BACKGROUND

The (neo)striatum is the major input structure of the basal nuclei, which is involved in the execution of voluntary movements, but also in controlling the processes that lead to the movement, such as motivation and cognition. The striatum provides its function through an interaction between projection neurons and interneurons. The aim of this study was to quantify the morphological properties of neurons in the precommissural putamen and precommissural caudate nucleus head and to evaluate whether there is a difference in cell morphology between different cell groups within one part and between the same cell groups within different parts of the striatum.

METHODS

A total of 652 neuronal images of human striatum were observed. The features of the neuronal morphology (soma size, dendritic field size, shape of neuronal image, dendritic curviness, dendritic branching complexity) were observed by determining appropriate parameters of digital images of neurons.

RESULTS

According to the presence of spines on the soma and/or dendrites, neurons were qualitatively classified into 446 spiny and 206 aspiny cells. The analysis of the distribution of the dendritic field area shows that spiny and aspiny neurons from both parts of the neostriatum can be decomposed into two distributions, which means that they can be classified into subgroups. A quantitative analysis of the spiny/aspiny neurons in the human putamen or caudate nucleus head has shown that there is a statistically significant difference between them. By comparing the morphology of neurons of the same group between different parts of the human neostriatum (putamen and caudate nucleus), it was also determined that there is a statistically significant difference.

CONCLUSION

Since the morphology and function of neurons are in close correlation, it can be assumed that different groups of neurons in the human striatum might support functional diversity of the studied area.