Bezugspotential

Bezugspotential, or reference potential, is the electrical potential at the reference electrode used to define and interpret bioelectric measurements in electrophysiology. In practice, most recordings measure potentials as differences relative to this reference electrode, rather than as absolute potentials. In EEG and related techniques, the recorded signal is typically described as V_recorded = V_active − V_reference. Because the reference site can itself pick up brain activity and various forms of noise, the choice of Bezugspotential strongly influences the appearance of waveforms, amplitudes, and spatial maps.

Common reference schemes include a fixed recording site, such as the earlobe or mastoid process, the nose, or a central scalp location like Cz. An alternative is the average reference, which uses the mean potential across all recording electrodes as the reference. More sophisticated methods aim to reduce reference-related distortion; examples include the REST (reference electrode standardization technique), which estimates a reference at infinity, and various re-referencing approaches applied during data analysis.

The Bezugspotential is not an absolute measure of brain activity; it is a property of the measurement system and the electrode configuration. It can be affected by electrode impedance, skin potentials, movement, and environmental noise. Consequently, researchers must consider reference choice when designing experiments, comparing studies, or re-referencing data during analysis in order to ensure consistent interpretation of ERP components and other neurophysiological signals.