Laboratory for electrophysiology

 

Description

The Electrophysiology Laboratory provides the infrastructure for a variety of non-invasive examination possibilities of electrical processes on biological objects. The installations are implemented according to the principle of the greatest possible interference protection for the derivation of bioelectrical signals. In the research carried out here, the entire chain from the electrode for bio-signal derivation or stimulation imprinting, the electrode-skin contact to the signal processing in the biological object is investigated. Innovative electrode concepts for current stimulation and EEG recording are characterized and tested on test participants. The effect of visual and auditory stimuli as well as current stimulation on neuronal activity in the brain is investigated in EEG studies.

The laboratory is used both for classical education in the bachelor and master courses and for scientific studies to be carried out when working on research projects.

The knowledge gained should help to improve the diagnosis and therapy of neuropsychiatric diseases and make electrical stimulation manageable for further applications.

Figure 1 Insights into the Electrophysiology Laboratory

Equipment

 

Cap-based multichannel-EEG-systems (ANT Neuro)

  • 64 / 128 / 256 - channel dry and wet Waveguard EEG caps
  • 64 / 128 / 256 - channel eego amplifiers
  • 256-channel TMSI amplifier

Single electrode based EEG-System (neuroConn)

  • 32-channel NeuroPrax
  • Trigger modules

Eevoke stimulation system

  • Visual (LCD, LED)
  • Auditory

Constant current stimulators

  • DC Stimulator Plus (neuroConn)
  • DC Stimulator MC (neuroConn)
  • DS 7A (Digitimer)
  • DS 5 (Digitimer)

Impedanz spectrographs

  • Reference 600 Plus (Gamry)
  • Agilent 4192A (Hewlett Packard)

Digitizing systems

  • Xensor 3D electrode digitization (ANT Neuro)
  • 3D structured light scanner (Scan in a Box)
 

Application / study examples

  • Characterization and verification of stimulation electrodes

Stimulation electrodes are developed for different application scenarios, e.g. transcranial electric stimulation and electrical warning. In this laboratory, the impedance properties of the different electrodes are characterized by four-point measurements. Electrodes suitable for use in humans are verified with regard to their functionality for the desired current application in participant studies.

 
Figure 2 Setup of a four-point measurement for material characterization
Figure 3 Simultaneous VEP measurement and TES with bifunctional cap
Figure 4 Setup for electrical stimulation of the skin using the Isolated Bipolar Current Stimulator DS5 and the Multiplexer D188, both from Digitimer Ltd (UK)
 
Figure 5: Dry EEG cap with 97 channels and image of a source reconstruction of auditory activity in the brain.
  • Characterization and verification of measurement electrodes
 

Innovative measurement electrodes for EEG and ECG applications are developed at the BMTI and in the electrophysiological laboratory characterized and tested in participant studies regarding their functionality in comparison to conventional electrode systems.