Oxygen-Induced and pH-Induced Direct Current Artifacts on Invasive Platinum/Iridium Electrodes for Electrocorticography.

The magnitude of pO2-induced subdural DC shifts by approximately 6 mV was similar to that of SDs, but they did not show a sequential onset at adjacent recording sites, could be either predominantly negative or positive in contrast with the always negative DC shifts of SD, and were not accompanied by brain activity depression. Opposing polarities of pO2-induced DC artifacts may result from differences in baseline electrode polarization or subdural ptiO2 inhomogeneities relative to subdermal ptiO2 at the quasi-reference.