Information Technology Reference
In-Depth Information
Chapter 8
Neuroelectromagnetic Source Imaging of Brain
Dynamics
Rey R. Ramırez, David Wipf, and Sylvain Baillet
Abstract
Neuroelectromagnetic source imaging (NSI) is the scientific field devoted
to modeling and estimating the spatiotemporal dynamics of the neuronal currents
that generate the electric potentials and magnetic fields measured with electromag-
netic (EM) recording technologies. Unlike functional magnetic resonance imaging
(fMRI), which is indirectly related to neuroelectrical activity through neurovascu-
lar coupling [e.g., the blood oxygen level-dependent (BOLD) signal], EM measure-
ments directly relate to the electrical activity of neuronal populations. In the past few
decades, researchers have developed a great variety of source estimation techniques
that are well informed by anatomy, neurophysiology, and the physics of volume con-
duction. State-of-the-art approaches can resolve many simultaneously active brain
regions and their single trial dynamics and can even reveal the spatial extent of local
cortical current flows.
8.1 Introduction
NSI methods model and estimate the spatiotemporal dynamics of neuronal currents
throughout the brain as accessed by noninvasive and invasive surface measurements
such as electroencephalography (EEG), magnetoencephalography (MEG), and elec-
trocorticography (ECoG) [6, 22, 30, 31].
