text: The idea that the electrical activity generated by nervous tissue may influence the activity of surrounding nervous tissue is one that dates back to the late 19th century. Early experiments, like those by Emil du Bois-Reymond, demonstrated that the firing of a primary nerve may induce the firing of an adjacent secondary nerve (termed "secondary excitation"). This effect was not quantitatively explored, however, until experiments by Katz and Schmitt in 1940, when the two explored the electric interaction of two adjacent limb nerves of the crab Carcinus maenas. Their work demonstrated that the progression of the action potential in the active axon caused excitability changes in the inactive axon. These changes were attributed to the local currents that form the action potential. For example, the currents that caused the depolarization (excitation) of the active nerve caused a corresponding hyperpolarization (depression) of the adjacent resting fiber. Similarly, the currents that caused repolarization of the active nerve caused slight depolarization in the resting fiber. Katz and Schmitt also observed that stimulation of both nerves could cause interference effects. Simultaneous action potential firing caused interference and resulted in decreased conduction velocity, while slightly offset stimulation resulted in synchronization of the two impulses.
  In 1941 Angélique Arvanitaki explored the same topic and proposed the usage of the term "ephapse" (from the Greek  and meaning "to touch") to describe this phenomenon and distinguish it from synaptic transmission. Over time the term ephaptic coupling has come to be used not only in cases of electric interaction between adjacent elements, but also more generally to describe the effects induced by any field changes along the cell membrane.