Reference signal when measuring EEG?

What is reference electrode in EEG?

The physical reference is usually the electrode (e.g. Cz, Fz, Oz and FCz) placed over the scalp or the body surface during online recording setup. The virtual reference is the linearly combined signal of the recordings from all the electrodes, during offline processing after the EEG data acquisition.

What is common average reference?

In contrast, a common average reference minimizes uncorrelated sources of signal and noise through averaging, while eliminating sources of noise common to all sites. Therefore a common average reference more closely approximates the theoretical differential recording ideal.

How do you measure the for EEG?

EEG electrodes

  1. A technician measures your head and marks your scalp with a special pencil to indicate where to attach the electrodes. …
  2. A technician attaches discs (electrodes) to your scalp using a special adhesive. …
  3. You relax in a comfortable position with your eyes closed during the test.

Which type of electrode is used as reference electrode for EEG measurements?

The EEG References

In particular, the MM reference signal has been modeled by the average of the TP9 and TP10 electrodes that are located in the proximity of the mastoids.

Where do reference electrodes go?

In general, a reference electrode should be placed in a well-conducting medium close, or some distance away from the recording electrode. The idea of a reference electrode is that it picks up any unwanted signals, such as artifacts, that are also present on the recording electrode.

How does the reference electrode work?

Reference electrodes are electrodes with a stable and well-defined electrochemical potential against which the potential of other electrodes in the system can be controlled and measured. They are used in three electrode systems to perform electrochemical methods such as cyclic voltammetry or linear sweep voltammetry.

Why does EEG need to be averaged?

The prime reason for using the average reference in EEG source estimation is that in the forward model of how the sources project to the channels there is a (small) model error at each channel, including at the reference channel.