Pulse Modulation in Physiological Systems, Phenomenological Aspects

In the development of a quantitative understanding of physiological reflex arcs it becomes apparent that the concept of pulse-frequency modulation is bound to play an important part. Not only does the discrete nature of these signals introduce some effects of itself, but possibly more significant in the total picture are the dynamical factors introduced by the modulator and demodulator. There is good reason for feeling that in the iris reflex, for instance, a large share of the dynamic behavior is intimately related to the photoreceptors themselves, and possibly a minor role is taken by the synaptic delays.