We rely on various nonparametric time series techniques to quantify several autocorrelated Aplysia total motion activity series. The effect of light on total motion activity has been removed. A general model will be proposed for total motion activity, which is found to display a circadian rhythm, and the toxic effect of PCBs on total motion activity will be assessed. No underlying assumptions are made about the form of the circadian rhythm. Several types of circadian total motion activity patterns are discovered. We form the hypothesis that different data series may be separated into three distinct groups of common patterns of circadian total motion activity. We also investigate if in fact only a single innate oscillator regulates total motion activity.
