Which of the following is true with regard to electrode impedances?

Which of the following is true with regard to electrode impedances?

• A. When there is a difference in impedances between electrodes, the number of artifacts is reduced
• B. Impedance levels for each individual electrode should be less than or equal to 5k ohms
• C. The tech should verify the electrode impedances before calibrating the machine
• D. Electrodes should be tested together in groups of three

Answer: (B)

Maintaining low, balanced impedance at each electrode ensures a clean, stable EEG signal. Impedance is the resistance at the electrode–skin interface; when it’s too high or uneven across channels, the amplifier picks up more noise and artifacts, and signals can be distorted by imperfect common-mode rejection. Keeping each electrode at a low level helps the system accurately capture brain activity and minimizes interference from movement, sweating, or cable motion. The recommended target is that each individual electrode impedance be at or below 5 kiloohms. This standard threshold helps ensure the electrode signal is strong relative to noise and that the amplifier’s high input impedance can effectively measure it. When impedances are well balanced and low across all channels, you get more reliable recordings and fewer artifacts. The statement about differences in impedances reducing artifacts isn’t correct; imbalances tend to introduce or amplify artifacts. Verifying impedances is important, but the emphasis here is the per-electrode threshold rather than the exact sequence of steps like calibration. Testing electrodes in small groups isn’t reliable; you want each electrode tested individually to confirm its contact quality.

Maintaining low, balanced impedance at each electrode ensures a clean, stable EEG signal. Impedance is the resistance at the electrode–skin interface; when it’s too high or uneven across channels, the amplifier picks up more noise and artifacts, and signals can be distorted by imperfect common-mode rejection. Keeping each electrode at a low level helps the system accurately capture brain activity and minimizes interference from movement, sweating, or cable motion.

The recommended target is that each individual electrode impedance be at or below 5 kiloohms. This standard threshold helps ensure the electrode signal is strong relative to noise and that the amplifier’s high input impedance can effectively measure it. When impedances are well balanced and low across all channels, you get more reliable recordings and fewer artifacts.

The statement about differences in impedances reducing artifacts isn’t correct; imbalances tend to introduce or amplify artifacts. Verifying impedances is important, but the emphasis here is the per-electrode threshold rather than the exact sequence of steps like calibration. Testing electrodes in small groups isn’t reliable; you want each electrode tested individually to confirm its contact quality.