“…Earlier studies with monopolar recording during thalamic stereotactic surgery in humans showed the same findings (Baba et al, 1976). Using monopolar montages, premovement potentials with similar characteristics were recorded from contacts located in the putamen (Rektor et al, 2001) and subcortical white matter (Tsubokawa et al, 1976). Since the monopolar premovement potentials may reflect far field activity arising from structures between the intracerebral and scalp contacts, we used a bipolar montage between two consecutive contacts of the DBS electrode (i.e., 0–1, 1–2, 2–3), which picked up electrical signal from a small area close to the pair of recording contacts…”