The Relationship Between Local Field Potentials and the Blood-Oxygenation-Level Dependent MRI Signal Can Be Non-linear

• Type of Material: Article
• Authors: Xiaodi Zhang, Emory University; Wenju Pan, Emory University; Shella Keilholz, Emory University
• Language: English
• Date: 2019-10-25
• Publisher: FRONTIERS MEDIA SA
• Publication Version: Final Published Version
• Copyright Statement: © 2019 Zhang, Pan and Keilholz.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.3389/fnins.2019.01126
• Title of Journal or Parent Work: FRONTIERS IN NEUROSCIENCE
• Volume: 13
• Start Page: 1126
• End Page: 1126
• Grant/Funding Information: This work was supported by NIH 1 R01NS078095-01, BRAIN initiative R01 MH 111416, and NSF INSPIRE. The authors would like to thank Chinese Scholarship Council (CSC) for financial support and Center for Systems Imaging Core.
• Keywords: DEXMEDETOMIDINE; Science & Technology; non-linearity; NEURAL ACTIVITY; BRAIN; Neurosciences; FMRI; BOLD; VISUAL-CORTEX; correlation; local field potentials; fMRI; STIMULATION; Neurosciences & Neurology; NEURONAL-ACTIVITY; neurovascular coupling; SPONTANEOUS FLUCTUATIONS; Life Sciences & Biomedicine; FUNCTIONAL CONNECTIVITY; electrophysiology
• Research Categories: Biology, Neuroscience; Health Sciences, Radiology

Abstract

Functional magnetic resonance imaging (fMRI) is currently one of the most important neuroimaging methods in neuroscience. The image contrast in fMRI relies on the blood-oxygenation-level dependent (BOLD) signal, which indirectly reflects neural activity through neurovascular coupling. Because the mechanism that links the BOLD signal to neural activities involves multiple complicated processes, where neural activity, regional metabolism, hemodynamics, and the BOLD signal are all inter-connected, understanding the quantitative relationship between the BOLD signal and the underlying neural activities is crucial for interpreting fMRI data. Simultaneous local field potential (LFP) and fMRI recordings provide a method to study neurovascular coupling. There were a few studies that have shown non-linearities in stimulus related responses, but whether there is any non-linearity in LFP—BOLD relationship at rest has not been specifically quantified. In this study, we analyzed the simultaneous LFP and resting state-fMRI data acquired from rodents, and found that the relationship between LFP and BOLD is non-linear under isoflurane (ISO) anesthesia, but linear under dexmedetomidine (DMED) anesthesia. Subsequent analysis suggests that such non-linearity may come from the non-Gaussian distribution of LFP power and switching from LFP power to LFP amplitude can alleviate the problem to a degree. We also confirmed that, despite the non-linearity in the mean LFP—BOLD curve, the Pearson correlation between the two signals is relatively unaffected.