Electrophysiology and EEG Laboratories

The EEG (electroencephalogram) is a proven method for the non-invasive measurement of brain activity with high temporal accuracy and is used in the basic research of various Max Planck Research Groups. The Max Planck Institute for Biological Cybernetics has facilities equipped for this purpose in two institute buildings, which enable interference-free measurements. The precise localization of the electrodes and the combination with MRI images enable detailed reconstructions of the electrical activity in the brain.

The EEG records the electrical voltage differences on the surface of the human head, which are in the microvolt range. Special electrodes record these weak signals and amplify them for analysis. The resulting waveforms only provide a rough picture of brain activity, as the signals can change on their way from the nerve cells to the measurement. Nevertheless, the EEG in combination with other methods remains a valuable tool in basic neuroscientific research.

The EEG shows four typical frequency ranges: Alpha waves (8-13 Hz), Beta waves (14-30 Hz), Theta waves (4-8 Hz) and Delta waves (1-4 Hz). When awake, healthy people mainly experience alpha and beta waves. Alpha waves occur more strongly when you are relaxed. Slower waves such as theta and delta waves, on the other hand, are typical of sleep - delta waves in particular occur during deep sleep.

They show how the brain processes a particular stimulus. Based on the temporal sequence and the distribution of these signals on the scalp, conclusions can be drawn about the processes in the brain.