this week we will examine how action potentials in one region normally produce action potentials in adjacent regions, so that there is a sequence of action potentials, an excitation wave. the learning objectives for this week are: (1) Identify the differences between the propagation pattern following sub-threshold versus threshold stimuli; (2) Compute the changes in transmembrane potentials and currents from one time to a short time laterIdentify the outcome of stimulating a fiber at both ends; (3) Quantify the interval after propagation following one stimulus to the time when there will be another excitation wave following a 2nd stimulus; (4) Explain why "propagation" is different from "movement".