Functional Connectivity of the Brain Across Rodents and Humans.

Nan Xu,Shella Keilholz,Eric Maltbie,Nmachi Anumba,Gloria P Clavijo,Vahid Khalilzad Sharghi,Lisa Meyer-Baese,Wen-Ju Pan,Yasmine Bassil,Xiaodi Zhang,Behnaz Yousefi,Theodore J Lagrow,Azalea Lee,Maysam Nezafati

doi:10.3389/fnins.2022.816331

Nan Xu, Shella Keilholz + Show 12 more

Open Access

https://doi.org/10.3389/fnins.2022.816331

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Abstract

Resting-state functional magnetic resonance imaging (rs-fMRI), which measures the spontaneous fluctuations in the blood oxygen level-dependent (BOLD) signal, is increasingly utilized for the investigation of the brain’s physiological and pathological functional activity. Rodents, as a typical animal model in neuroscience, play an important role in the studies that examine the neuronal processes that underpin the spontaneous fluctuations in the BOLD signal and the functional connectivity that results. Translating this knowledge from rodents to humans requires a basic knowledge of the similarities and differences across species in terms of both the BOLD signal fluctuations and the resulting functional connectivity. This review begins by examining similarities and differences in anatomical features, acquisition parameters, and preprocessing techniques, as factors that contribute to functional connectivity. Homologous functional networks are compared across species, and aspects of the BOLD fluctuations such as the topography of the global signal and the relationship between structural and functional connectivity are examined. Time-varying features of functional connectivity, obtained by sliding windowed approaches, quasi-periodic patterns, and coactivation patterns, are compared across species. Applications demonstrating the use of rs-fMRI as a translational tool for cross-species analysis are discussed, with an emphasis on neurological and psychiatric disorders. Finally, open questions are presented to encapsulate the future direction of the field.

Highlights

Resting-state functional magnetic resonance imaging, which detects the spontaneous fluctuations in the blood oxygen level-dependent (BOLD) signal, is a powerful, non-invasive tool for the investigation of the brain’s intrinsic functional organization at the macroscale level
We aim to provide a comprehensive overview of features extracted from Resting-state functional magnetic resonance imaging (rs-fMRI) studies in humans and rodents, with the goal of identifying similarities and differences that are important for the translation of knowledge gained in rodents to studies in humans
It is crucial to acknowledge the diversity in the etiologies of Autism spectrum disorder (ASD) since only about 10% of ASD cases can be attributed to monogenic mutations (Liska and Gozzi, 2016)

Summary

Introduction

Resting-state functional magnetic resonance imaging (rs-fMRI), which detects the spontaneous fluctuations in the blood oxygen level-dependent (BOLD) signal, is a powerful, non-invasive tool for the investigation of the brain’s intrinsic functional organization at the macroscale level. Functional connectivity of the brain can be calculated by finding the Pearson correlation between the BOLD signals of different brain areas. This results in spatial maps reflective of the brain’s intrinsic functional organization (Biswal et al, 1995). Because the BOLD signal is only loosely and indirectly linked to the underlying neural activity, findings regarding such differences in functional connectivity can often be difficult to interpret. Over the last 20 years, rodent models have proven instrumental in understanding the neuronal and neurophysiological basis of spontaneous BOLD signal fluctuations and the consequent intrinsic functional connectivity (Pais-Roldán et al, 2021). The number of rs-fMRI studies in rodents increases each year (Figure 1), and such studies will continue to play a key role in interpreting the alterations of functional connectivity that are observed across conditions and groups

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