RESUMO
OBJECTIVE: Traditional electroencephalogram (EEG) recorders reject low frequencies and DC and therefore cannot handle fullband EEG. Dedicated fullband recorders use non-standard file formats, because the standard format (EDF) cannot handle large DC electrode offset voltages. Both facts limit the development and use of fullband EEG. We developed a modification that allows conventional equipment to record fullband EEG, and adapts both types of recorders to EDF. METHODS: The modification is a simple filter that attenuates the DC component and thus makes the EEG fit within traditional equipment limitations and EDF. The review software automatically 'de-attenuates' the DC component, without loss of information. RESULTS: DC attenuation by a factor of 10 made both types of recorders store DC attenuated fullband EEG into EDF files. Recordings were made during 0.5-24h in 46 subjects. The DC de-attenuator automatically reconstructed the original fullband EEG within an amplitude range of ±100mV and with a resolution of 0.3µV. Using sintered Ag-AgCl electrodes attached with common procedures, reconstructed DC EEG in spontaneously moving subjects ranged between ±32mV. CONCLUSIONS: The modification works. Fullband recordings can now be analyzed by independent software, archived and exchanged. SIGNIFICANCE: Any EEG system can be made to record fullband EEG into standard EDF.
