Input impedance in EEG systems should be:

Input impedance in EEG systems is a critical factor that impacts the quality of the recorded EEG signals. It should be very high to ensure that the system can accurately detect small electrical potentials generated by neuronal activity in the brain without significantly affecting the signal. High input impedance minimizes the loading effect on the scalp electrodes, allowing for the measurement of the weak bioelectrical signals that are typically on the order of microvolts.

When the input impedance is very high, the system can maintain fidelity in the signal capture, especially in the presence of electrical noise and other interference. This is particularly important because the brain's electrical activity can be subtle and easily masked by extraneous signals. A very high impedance helps to preserve the integrity of the EEG signal throughout the recording process.

In contrast, if the input impedance were low, it could lead to signal loss or distortion, as the EEG system would draw more current from the electrodes and potentially alter the actual brain signals being measured. Therefore, having a very high input impedance is essential for accurate and reliable EEG recordings.