Simultaneous EEG Monitoring During Transcranial Direct Current Stimulation

Abstract

Transcranial direct current stimulation (tDCS) is a technique that delivers weak electric currents through the scalp. This constant electric current induces shifts in neuronal membrane excitability, resulting in secondary changes in cortical activity. Although tDCS has most of its neuromodulatory effects on the underlying cortex, tDCS effects can also be observed in distant neural networks. Therefore, concomitant EEG monitoring of the effects of tDCS can provide valuable information on the mechanisms of tDCS. In addition, EEG findings can be an important surrogate marker for the effects of tDCS and thus can be used to optimize its parameters. This combined EEG-tDCS system can also be used for preventive treatment of neurological conditions characterized by abnormal peaks of cortical excitability, such as seizures. Such a system would be the basis of a non-invasive closed-loop device. In this article, we present a novel device that is capable of utilizing tDCS and EEG simultaneously. For that, we describe in a step-by-step fashion the main procedures of the application of this device using schematic figures, tables and video demonstrations. Additionally, we provide a literature review on clinical uses of tDCS and its cortical effects measured by EEG techniques.

The Use of Magnetic Resonance Spectroscopy as a Tool for the Measurement of Bi-hemispheric Transcranial Electric Stimulation Effects on Primary Motor Cortex Metabolism

“…Furthermore, as described in the present paper, 1 H-MRS is a useful technique that can be used to verify the underlying mechanisms of action of specific tDCS protocols that have been shown to improve symptoms in different clinical populations. Electrode positioning and duration of stimulation can be modified to investigate the effects of these specific tDCS protocols, such as those one used in the treatment of pain, depression, tinnitus, Parkinson's, migraine, and alcohol abuse (see 76 for a description of the protocols). It should also be noted that if the impedance level is above 20 kΩ, the device will not stimulate and display an impedance error message on the screen.…”

A technical guide to tDCS, and related non-invasive brain stimulation tools

“…At present, a few dedicated commercial systems are available that are specifically designed to integrate tES with EEG (Schestatsky et al 2013). In the following section, we will primarily consider how to integrate tES with EEG in the event that such a combined system is not used.…”

Novel methods to optimize the effects of transcranial direct current stimulation: a systematic review of transcranial direct current stimulation patents

“…Six new approaches included methods to quantify cortical changes, such as fMRI, fNIRS and EEG [29][30][31][32][33][34]. This combination would provide a base for future investigations using a real-time monitoring of cortical activity as well as using those measures as potential surrogates to optimize its use in clinical applications [48,49].…”