Chaos in plethysmograms during tracking chaos

A tracking experiment was designed to observe how chaotic variations in ear plethysmogram were related to tracking targets with different predictabilities including chaos. We found the maximum Lyapunov exponent computed from plethysmograms had higher value during tracking chaotic orbital signals in compare with both simply deterministic signal and random ones. Also there was found a lower variance of the difference between target and tracking during tracking the chaos target, whereas there was obviously large variance in tracking random target. A mathematical model consisting of baroreflex feedback and autonomous interactions was proposed to explain the changes in ear plethysmograms, pointing to give a guide in future applications using the tracking experiment. With the help of simulation, the model sowed that there was increased active temporal information processing in higher cerebral region during tracking chaos target.