EEG measurement during tACS and tRNS

NEURO PRAX TMS/tDCS full-band EEG currently measures EEG-signals during TMS or tDCS, however we can now use the same system to measure undisturbed EEG signals during an oscillating neuro-stimulation with small alternating currents, known as tACS (transcranial alternating current stimulation) or tRNS (transcranial random noise stimulation).

EEG measurement

This is achieved with re-designed hardware, and software improvements that remove stimulation induced noise from the EEG signal online and in real time.    

  • Top: tACS/EEG (left) & tRNS/EEG (right) without correction.
  • Bottom: Corrected tACS/EEG and tRNS/EEG after online correction of stimulation induced noise.

About tACS-EEG

tACS-EEG is a non-invasive and painless method to evaluate the modulation of cortical oscillatory brain activity and cerebral plasticity simultaneously with stimulation. Latest investigations in neuroscience provide a wide range of research topics for tACS-EEG for example:

  • the modulation of oscillatory brain activity at a specific frequency;
  • studying interactions between EEG rhythms of different frequencies;
  • frequency tuning of cortical areas for optimal TMS;
  • gaining knowledge on brain oscillations for basic science and for therapeutic application.

The next generation of the neuroConn DC-STIMULATOR PLUS can be delivered with the optional SIGNAL OUT module, which provides a galvanically isolated reference signal.   A cable transfers this reference signal from the signal output of the DC-STIMULATOR PLUS to the EEG amplifier of the NEURO PRAX TMS/tDCS. Rogue-Resolutions-tDCS-EEG-Signal-Out-OptionNEURO PRAX TMS/tDCS records the incoming reference signal and with our innovative ONLINE Correction software utilizes the reference signal to remove the artefacts induced by the stimulation from all EEG channels in real time.   Both the new DC-STIMULATOR PLUS with optional SIGNAL OUT and the online correction software for the NEURO PRAX TMS/tDCS are available now.

Publications demonstrating tACS-EEG:  

Transcranial Electrical Currents to Probe EEG Brain Rhythms and Memory Consolidation during Sleep in Humans. Stimulation at 0.75 Hz and at THETA range (5 Hz) – both only anodal, i.e. with offset – effect on sleep & Memory consolidation and in the EEG-GAMMA range.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3038929/

Transcranial Alternating Current Stimulation Enhances Individual Alpha Activity in Human EEG. Stimulation at individual ALPHA leads to changes in EEG spectra power (ALPHA band) and might cause spike depended Long Term Potentiation.

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0013766

Frequency-Dependent Tuning of the Human Motor System Induced by Transcranial Oscillatory Potentials. Stimulation at 20 Hz shows significant effect on MEP threshold.

http://www.jneurosci.org/content/31/34/12165.full

Transcranial alternating current stimulation (tACS) modulates cortical excitability as assessed by TMS-induced phosphene thresholds. Stimulation at 20 Hz shows significant effect on PHOSPHENE threshold.

http://www.sciencedirect.com/science/article/pii/S138824571000310X

Transcranial electrical stimulation (tES – tDCS; tRNS, tACS) methods. A review on tACS/tRNS.

http://www.tandfonline.com/doi/pdf/10.1080/09602011.2011.557292

Entrainment of Perceptually Relevant Brain Oscillations by Non-Invasive Rhythmic Stimulation of the Human Brain. A review on ENTRAINMENT (rTMS / tACS with EEG).

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3142861/

Important: tACS-EEG is not possible with older versions of the neuroConn DC-STIMULATOR PLUS with a serial number < 1000.

Please contact us for an upgrade of your DC-STIMULATOR PLUS to the functionalities of the new generation and for the additional hardware module “SIGNAL OUT”.