When using the average reference, how can a spike and wave focus at C3 be best enhanced?

When utilizing the average reference technique in EEG, enhancing a spike and wave focus at a specific site, such as C3, can be more effectively achieved by excluding that site and its surrounding electrodes from the reference calculation. This approach allows the activity at C3 to be represented independently, which may result in a more pronounced visualization of the spikes and waves specific to that location.

By excluding C3 and the surrounding electrodes from the reference, the contribution from these sites is removed from the overall reference average. This modification increases the contrast of the signals at C3, as it allows for a clearer depiction of the local brain activity without dilution from nearby electrodes that may not be capturing the same spike and wave activity. Hence, this method can help in isolating and enhancing the clinical features of interest in the EEG recording.