When adjusting electrode impedances in a digital system, which value is typically targeted?

In digital systems used for neurophysiological monitoring, such as EEG or EMG, electrode impedance plays a critical role in signal quality. The typical target for electrode impedance is around 1 M ohm. This value is significant because it strikes a balance between maintaining a high input resistance, which minimizes the loading effect on the neural signals, and ensuring that the signal quality remains intact for accurate data recording.

When electrode impedances are at approximately 1 M ohm, the system can effectively pick up the bioelectrical signals while minimizing the interference from external noise and other artifacts. A higher impedance allows for better sensitivity in detecting small electrical changes in the body, which is essential for accurate diagnostics and monitoring.

The other values provided in the options do not provide the optimal balance for bioelectrical signal quality. Lower values (such as 100 ohms or 500 ohms) could lead to increased noise and potential distortion due to a more significant effect of stray capacitance and external interference. While 10 k ohms is a somewhat reasonable impedance, it may not be high enough to ensure minimal loading and optimal signal integrity; thus, it's not the typical target in this context.