In vivo labeling and quantitative imaging of neurons using MRI

TL;DR

This paper introduces a novel in vivo MRI-based method for labeling and quantifying neurons by using a virus to express a protein that enhances contrast agent uptake, enabling detailed neural circuit imaging.

Contribution

The study presents a new strategy combining viral gene delivery and contrast-enhanced MRI for in vivo neuronal labeling and quantification, advancing neural circuit imaging techniques.

Findings

Neurons can be specifically labeled using viral delivery of oatp1a1 gene.

Labeled neurons are visible as bright spots on T1-weighted MRI images.

Quantitative measures of labeled neurons are obtained through dynamic contrast enhancement.

Abstract

Mammalian brain is a complex organ that contains billions of neurons. These neurons form various neural circuits that control the perception, cognition, emotion and behavior. Developing in vivo neuronal labeling and imaging techniques is crucial for studying the structure and function of neural circuits. In vivo techniques can provide true physiological information that cannot be provided by ex vivo methods. In this study, we describe a new strategy for in vivo neuronal labeling and quantification using MRI. To demonstrate the ability of this new method, we used neurotropic virus to deliver oatp1a1 gene to the target neural circuit. OATP1A1 protein is expressed on the neuronal membrane and can increase the uptake of a specific MRI contrast agent (Gd-EOB-DTPA). By using T1-weighted images for observation, labeled neurons "light up" on MRI. We further use a dynamic-contrast-enhancement based method to obtain measures that provide quantitative information of labeled neurons in vivo.