title: Visualizing simulated electrical fields from electroencephalography and transcranial electric brain stimulation: a comparative evaluation.
abstract: Electrical activity of neuronal populations is a crucial aspect of brain activity. This activity is not measured directly but recorded as electrical potential changes using head surface electrodes (electroencephalogram - EEG). Head surface electrodes can also be deployed to inject electrical currents in order to modulate brain activity (transcranial electric stimulation techniques) for therapeutic and neuroscientific purposes. In electroencephalography and noninvasive electric brain stimulation, electrical fields mediate between electrical signal sources and regions of interest (ROI). These fields can be very complicated in structure, and are influenced in a complex way by the conductivity profile of the human head. Visualization techniques play a central role to grasp the nature of those fields because such techniques allow for an effective conveyance of complex data and enable quick qualitative and quantitative assessments. The examination of volume conduction effects of particular head model parameterizations (e.g., skull thickness and layering), of brain anomalies (e.g., holes in the skull, tumors), location and extent of active brain areas (e.g., high concentrations of current densities) and around current injecting electrodes can be investigated using visualization. Here, we evaluate a number of widely used visualization techniques, based on either the potential distribution or on the current-flow. In particular, we focus on the extractability of quantitative and qualitative information from the obtained images, their effective integration of anatomical context information, and their interaction. We present illustrative examples from clinically and neuroscientifically relevant cases and discuss the pros and cons of the various visualization techniques.
authors.affiliation: Image and Signal Processing Group, Leipzig University, Augustusplatz 10-11, 04109 Leipzig, Germany. Electronic address: eichelbaum@informatik.uni-leipzig.de.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Eichelbaum
authors.affiliation: Scientific Computing and Imaging Institute, University of Utah, 72S. Central Campus Drive, 84112 Salt Lake City, UT, USA; Center for Integrative Biomedical Computing, University of Utah, 72S. Central Campus Drive, 84112, Salt Lake City, UT, USA. Electronic address: moritz@sci.utah.edu.
authors.forename: Moritz
authors.initials: M
authors.lastname: Dannhauer
authors.affiliation: Scientific Visualization, Leipzig University, Augustusplatz 10-11, 04109 Leipzig, Germany. Electronic address: hlawitschka@informatik.uni-leipzig.de.
authors.forename: Mario
authors.initials: M
authors.lastname: Hlawitschka
authors.affiliation: Center for Integrative Biomedical Computing, University of Utah, 72S. Central Campus Drive, 84112, Salt Lake City, UT, USA; Department of Electrical and Computer Engineering, Northeastern University, Boston, MA, USA. Electronic address: brooks@ece.neu.edu.
authors.forename: Dana
authors.initials: D
authors.lastname: Brooks
authors.affiliation: Human Cognitive and Brain Sciences, Max Planck Institute, StephanstraÃŸe 1a, 04103 Leipzig, Germany. Electronic address: knoesche@cbs.mpg.de.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Knösche
authors.affiliation: Image and Signal Processing Group, Leipzig University, Augustusplatz 10-11, 04109 Leipzig, Germany. Electronic address: scheuermann@informatik.uni-leipzig.de.
authors.forename: Gerik
authors.initials: G
authors.lastname: Scheuermann
mesh_terms: D003196:Computer Graphics / Q000592:standards*; D004569:Electroencephalography / Q000379:methods*; D006801:Humans; D008488:Medical Illustration; D065908:Transcranial Direct Current Stimulation / Q000379:methods*
keywords: Bioelectric Field; EEG; Human Brain; Visualization; tDCS