Fig. 7

Raw signal quality across recording locations. 10-s electroencephalogram (EEG) and electrocardiogram (ECG) data excerpts shown with uniform scaling (EEG 5× magnified compared to ECG) across plots for comparison of signal quality across active behaviors, i.e., galumphing or swimming) and distinct sleep states, i.e., slow-wave sleep (SWS) and rapid-eye-movement sleep (REM)). We show usable ECG in red (automated peak-detection possible), usable EEG in blue (no movement artifacts—visual and quantitative sleep state analysis possible with unprocessed raw signals), and unusable EEG in gray. We detected heart rate, but not sleep state, while the animal was active on land (1A) and in water (2A, 3A, and 4A). We were able to detect sleep state (difference between SWS and REM) when the animal was calm, whether that was on land (1B, C), stationary in water (2B, C), or drifting at the surface (3D, E)