Why is the use of the 60Hz notch filter discouraged during recording?

The use of the 60Hz notch filter is discouraged during recording primarily because it can produce ringing activity that contaminates the response. This phenomenon occurs due to the nature of how notch filters operate; they are designed to remove a specific frequency, in this case, 60Hz, which is typically associated with electrical noise from power sources. However, the filtering process can inadvertently introduce artifacts such as ringing or overshoot around the edges of the filtered frequency, which may manifest as unwanted oscillations or distortions in the signal being recorded.

These artifacts can significantly interfere with the clarity and integrity of the neurophysiological signals that are being measured, possibly masking important data or leading to misinterpretation of the results. Therefore, while the intention behind using a notch filter is to eliminate noise, the resulting artifacts can prove to be detrimental in a clinical monitoring setting.

In contrast, options suggesting risks to the patient or issues with the electrodes are not relevant to the specific impact of the 60Hz notch filter on the integrity of the data recorded, and filtering slow activity does not align with the purpose or behavior of notch filters, which specifically target a specific frequency rather than broad bands of activity.