Which statement best describes impedance in EEG recording?

Which statement best describes impedance in EEG recording?

• A. The speed of signal
• B. The electrical resistance at the electrode-skin interface
• C. The amplitude of the signal
• D. The frequency response of the amplifier

Answer: (B)

Impedance in EEG is the opposition to current flow at the electrode-skin interface. In practice, this is mainly about how well the electrode contacts the scalp and how much noise that contact introduces, since a higher impedance means more vulnerable, unstable signals and more susceptibility to interference. The statement that impedance is the electrical resistance at the electrode-skin interface correctly captures this idea, because it reflects the quality of the contact that governs how clean and stable the recorded EEG signal will be. Impedance isn't about how fast the signal travels, the signal’s amplitude, or the amplifier’s frequency response—those describe other aspects of EEG recording. Lower impedance improves signal-to-noise and reduces drift, so clinicians and technicians work to optimize skin prep, use conductive gel or paste, and ensure good electrode placement to keep impedance low.

Impedance in EEG is the opposition to current flow at the electrode-skin interface. In practice, this is mainly about how well the electrode contacts the scalp and how much noise that contact introduces, since a higher impedance means more vulnerable, unstable signals and more susceptibility to interference. The statement that impedance is the electrical resistance at the electrode-skin interface correctly captures this idea, because it reflects the quality of the contact that governs how clean and stable the recorded EEG signal will be.

Impedance isn't about how fast the signal travels, the signal’s amplitude, or the amplifier’s frequency response—those describe other aspects of EEG recording. Lower impedance improves signal-to-noise and reduces drift, so clinicians and technicians work to optimize skin prep, use conductive gel or paste, and ensure good electrode placement to keep impedance low.