Investigation of pupil control with linear and nonlinear signal processing techniques

Pupil is controlled by the activity of the autonomous system. Under constant light and visual stimulus, it performs complex size oscillations and movements. Here, it is assumed that pupil behavior can be described by some unknown nonlinear deterministic rules. The techniques of time series embedding are applied to pupil size, obtaining a trajectory in the phase space. A trajectory is also obtained considering the movements of the eye. Indexes are obtained from Fourier analysis and from recurrence quantification analysis applied to trajectories in the phase space of the time series sampling pupil size and movement. Some insight into pupil control is obtained investigating data recorded in different stationary conditions (light vs darkness, rest position of the jaw vs dental occlusion).