A cross-referencing method for simultaneous slow and multiple unit potential recording with implanted electrodes

The effective pairing of a non-polarizing Ag-AgCl with an adjacent polarizing stainless steel minielectrode for simultaneous recording of slow or sustained potentials, conventional ECoG, and multiple unit potentials is demonstrated. The two types of electrode reciprocate their reference functions, the non-polarizing electrode being insensitive to the low voltage 1500-2500 kHz signal transmitted by the polarizing member and the latter being insensitive to the slow potentials (0-0.5 Hz) detected by the non-polarizing member. The method enables obtaining unambiguous information from a localized source in bipolar derivations and permits use of construction methods simpler than those required for the hybrid electrodes formerly used.