What is the term for no difference in electrical potential in EEG?

The term for no difference in electrical potential in EEG is commonly referred to as "equipotential." In the context of an EEG, equipotential signifies that the electrical potentials at various points are the same, which can be critical in understanding baseline activity and noise reduction in EEG signals.

In-phase cancellation refers to a phenomenon where signals of the same frequency and phase cancel each other out, which is not directly related to electrical potential differences but more about signal processing and can occur during certain types of filtering or interference.

Common mode rejection is a principle used in differential amplification, which involves rejecting common signals (noise) that are present on both inputs of a differential amplifier while allowing the difference signal to pass through. It's crucial for enhancing signal quality but does not itself describe a state of no difference in electrical potential.

The answer combines both concepts encapsulated in equipotential and aspects of in-phase cancellation, suggesting a trained understanding that both ideas touch on the concept of voltage differences, even if they emphasize slightly different phenomena. However, the primary term for describing a state of no potential difference is indeed equipotential.