Question about recordings of subject chb09.

[wosimidwa]

Currently, I am trying to preprocess an EEG dataset for a research project. The dataset I am working with this CHB-MIT EEG Scalp Dataset. Normally the dataset have used 23 channels for recordings however, at the subject named as chb09 they have used one more channel which is VNS. As I searched the Web, I have learned that it is a device used to send signals to the brain but in some articles they mention that it does not have any effects on EEG data recordings (egg: Vagus nerve stimulation has no effect on awake EEG rhythms in humans - PubMed ). Do you know the effect of VNS channel on EEG data recordings and how can it be reduced?