Billions of nerve cells work together in the brain to coordinate sensory input, thoughts, and emotions at any given moment. The nerve cells communicate with each other by means of electrochemical transmission. Electroencephalography (EEG) makes it possible to record the electrical activity of clusters of nerve cells as reflected in changes in electric potential at various locations on the scalp.

EEG was the first noninvasive technique developed to measure brain activity. It can be used on people who are sleeping, resting, or performing tasks in the lab. Thanks to the method’s high temporal precision (with a resolution of under 1 ms), it remains indispensable both in clinical settings and in experimental research on healthy study participants.

There are four measuring cabins in the EEG laboratory at the MPI for Human Development. Each cabin is shielded against both sound and electromagnetic radiation to ensure that the EEG measurements are as free of interference as possible. A modular amplifier system allows EEG recordings of high spatial resolution (32–128 channels per participant). Further systems for simultaneously recording other biosignals are also available. For example, an electrocardiogram (ECG) can be used to monitor the activity of the heart or an electromyogram (EMG) to measure muscle activity. Respiration, skin conductance, and pulse may also be measured depending on the experiment. A system for the three-dimensional localization of electrodes allows the position of the electrodes on the head to be determined with millimeter precision. In combination with structural magnetic resonance imaging (MRI), it is thus possible to precisely reconstruct the electrical activity of the brain.

Measurement Procedures

This picture shows an EEG cap on a wooden head.


An EEG recording from the scalp is completely safe and noninvasive, but a certain amount of preparation is needed. In our EEG lab, measurements are taken by (passive and active) electrodes mounted on an elastic cap.
This picture shows a subject with an EEG cap on his head.

Putting on the EEG cap

Electrode gel is used to achieve good contact between the scalp and the electrodes. The gels we use are hypoallergenic and generally do not cause skin irritation or rashes.
This picture shows a research assistant with a subject sitting next to her with an EEG cap on his head.

Start of the experiment

After the cap has been put on, the electrodes will be hooked up to the EEG machine. You will then take a seat in one of the EEG cabins, and the experiment can start.
This image shows a subject with an EEG cap on his head in front of a screen.

The experiment itself

In the experiment you might, for example, be shown pictures on a computer screen and asked to respond by pressing a button. The content and duration of the experiment will depend on the research question being addressed.
This picture shows a researcher in front of a computer.

Data analysis

The data assessed will be used to understand how people coordinate their activities—for example, when walking side by side, participating in team sports, or playing music together.
This picture shows the washing stations in the EEG lab.

After the measurement

When the EEG measurement is completed, you can use one of the wash basins to wash the remaining electrode gel out of your hair.
This image shows a water jet being used to clean the EEG cap.

Cleansing of the EEG cap

Throughout the entire preparation and measurement phase, you will be looked after by staff with specialized training in EEG measurement procedures. They will also ensure that the EEG cap is thoroughly cleaned after use.

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