ABSTRACT
This chapter reviews some of the experimental observations conducted on parallel, unmyelinated, excitable fibers. One consequence of pulse trapping occurs when both fibers, which are electrically coupled, are stimulated to carry uniform trains of pulses of different frequencies. Because some pulses on the neighboring fibers will not trap while other pulses will trap and change speed, the interaction can shift the distribution of pulses such that the frequencies can vary in an oscillatory fashion. The chapter examines some interaction phenomena via a cable theory model similar to Markin’s model. Unlike Markin’s approach, it considers only a continuous current-voltage relationship. The idea of cable theory is to consider the membranes of two parallel, unmyelinated axons as composed of equivalent electrical circuits. The results of the interaction phenomena indicate that if a sufficient number of fibers comprising an active bundle are simultaneously stimulated, then ephaptic transmission is possible.
