The Pupil as a Paradigm for Neurological Control Systems

Mathematical models of the pupiflary system were introduced in connection with the control or transfer function analysis of the pupil reflex to light by Stark and Sherman [1] and by Stark [2], [3]. Indeed, the pupil was the paradigm for the application of control theory to a biological system. We review here: 1) the pupil as a control system for light, 2) high gain oscillations, 3) noise, 4) kernel identification of nonlinearities, and 5) experimental evidence for heuristic nonlinear models.