EEG electrode digitization with commercial virtual reality hardware

Abstract

Accurate spatial co-registration of EEG electrode positions with individual head models is an important component for EEG source localization and imaging. Due to variations in head shape between individuals, this requires measurements of electrode locations in each individual. Existing hardware for digitization can be accurate, but also relatively expensive. With the goal of making digitization more accessible for a range of research laboratories, we have developed an open-source software tool that can make use of less expensive consumer virtual reality hardware for EEG electrode digitization. Here we describe our developed VRDigitizer system and compare it to existing digitization solutions. Experimental evaluations were performed in a phantom head model and in 12 human subjects. In our comparison experiments, VRDigitizer was able to measure electrode positions with a mean error of 3.74 mm, compared to 1.73 mm and 2.98 mm for the commercial systems tested.

More Reliable EEG Electrode Digitizing Methods Can Reduce Source Estimation Uncertainty, but Current Methods Already Accurately Identify Brodmann Areas

“…An electromagnetic system tracks the locations of receivers placed on the person's head and on a wand in an emitted electromagnetic field to estimate the position of the tip of the wand with respect to the head receivers. The environment must be clear of magnetic objects when using an electromagnetic digitizing system, otherwise the electrode locations will be warped (Engels et al, 2013; Cline et al, 2018).…”

“…Motion capture could also be used to record the position of the tip of a probe, a rigid body with multiple markers, to digitize 3D locations of the electrodes with respect to the reflective face markers. Several recent commercial digitizing systems use simple motion capture approaches to digitize EEG electrode locations with or without a probe (Cline et al, 2018; Song et al, 2018; ANT-Neuro, 2019; Rogue-Resolutions, 2019).…”

More Reliable EEG Electrode Digitizing Methods Can Reduce Source Estimation Uncertainty, But Current Methods Already Accurately Identify Brodmann Areas

“…An electromagnetic system tracks the locations of receivers on a wand in an emitted electromagnetic field to estimate the position of the tip of the wand. The environment must be clear of magnetic objects when using an electromagnetic digitizing system, otherwise the electrode locations will be warped [26], [27]. Recent efforts have focused on developing technologies to make digitization more accessible and convenient, mainly by incorporating image-based technologies [28], [29].…”

“…Motion capture could also be used to record the position of the tip of a probe, a rigid body with multiple markers, to digitize 3D locations of any point in the capture volume. Several recent commercial digitizing systems use simple motion capture approaches to digitize EEG electrode locations with or without a probe [27], [33]- [35].…”

“…Studies suggest that 3D scanners can improve digitization accuracy and significantly reduce digitization time [39]. Using other camerabased systems such as time-of-flight scanners and virtual reality headsets were also reported to provide comparable digitization reliability as the ultrasound or electromagnetic digitizing methods, while reducing the time spent for digitizing the EEG electrodes [27], [40], [41].…”