Removal of ECG interference from the EEG recordings in small animals usingindependent component analysis

In experiments involving small animals, the electroencephalogram (EEG) reco rded during severe injury and accompanying resuscitation exhibit the strong presence of electrocardiogram (ECG). For improved quantitative EEG (qEEG) analysis, it is therefore imperative to remove ECG interference from EEG. I n this paper, we validate the use of independent component analysis (ICA) t o effectively suppress the interference of ECG from EEG recordings during n ormal activity, asphyxia and recovery following asphyxia. Two channels of E EG from five rats were recorded continuously for 2 h. Simultaneous recordin g of one channel ECG was also made. Epochs of 4 s and 1 min were selected f rom baseline, asphyxia and recovery (every 10 min) and their independent co mponents and power spectra were calculated. The improvement in normalized p ower spectrum of EEG obtained for all animals was 7.71 +/- 3.63 db at the 3 rd minute of recovery and dropped to 1.15 +/- 0.60 db at 63rd minute. The a pplication of ICA has been particularly useful when the power of EEG is low , such as that observed during early brain hypoxic-asphyxic injury. The met hod is also useful in situations where accurate indications of EEG signal p ower and frequency content are needed. (C) 2001 Elsevier Science B.V. All r ights reserved.