Combining EEG and HD-tES Fully mobile EEG devices

Often, we hear that pioneering research labs are looking into ways of combining EEG and HD-tES.
While there can be certain challenges on mechanical compatibility and electrical compatibility side,
we propose a solution that makes this integration straightforward and user-friendly.

Soterix Medical stimulation and mBrainTrain wireless EEG systems can be combined for sleep and
awake experiments to acquire research-grade EEG data while providing optimized HD-tES.

Picture 1. Soterix Medical HD holders inserted into EEG cap

Soterix Medical HD Holders can be inserted at any location inside the mBrainTrain EEG cap. Custom Hybrid holders are also available that allow stimulation and recording from the same location.

Two fundamental issues underpin the rational integration of tDCS and EEG: mechanical compatibility and electrical compatibility.

1. Electrical Compatibility with HD-tES:

Electrical compatibility with optimized stimulators and rational experimental design is important. It is not prudent to assume that simple high-pass filtering of the EEG signal will remove confounds from EEG recording. Especially given that DC artifacts may be non-stationary due to unknown electrode impedance changes during stimulation and that EEG amplifier active electronics can induce non-linear distortion, Soterix Medical biomedical engineers have developed protocols to implement and validate EEG+tDCS compatibility. Note that conventional experimental control arms, such as using sham stimulation or a control-montage, will not in themselves control for EEG+tDCS distortion precisely because the stimulation has been changed (e.g. only the active arm will experience artifact). Soterix Medical’s and mBrainTrain’s unmatched technical support is ready to guide you through a straightforward validation process.

Picture 2. Noise Comparison between SMI device and Other Commercial Devices

2. Mechanical compatibility with HD-tDES:

Soterix Medical offers a simple and unique solution to tDCS+EEG through the use of High-Definition
(HD) tDCS electrodes. Compact in size and gel-based, with validated tolerability, HD electrodes can
be inserted between EEG electrodes without compromising mechanical compatibility.

HD electrodes are compatible with any Soterix Medical tDCS/tES or HD-tDCS/HD-tES stimulator.
Moreover, Soterix Medical provides HD electrode holders for integration with all mBrainTrain EEG
systems.