text: The early work performed by Katz and Schmitt demonstrated that ephaptic coupling between the two adjacent nerves was insufficient to stimulate an action potential in the resting nerve. Under ideal conditions the maximum depolarization observed was approximately 20% of the threshold stimulus. However, conditions can be manipulated in such a way that the action potential from one neuron can be spread to a neighboring neuron. This was accomplished in one study in two experimental conditions: increased calcium concentrations, which lowered the threshold potential, or by submerging the axons in mineral oil, which increased resistance. While these manipulations do not reflect normal conditions, they do highlight the mechanisms behind ephaptic excitation.
  Ephaptic coupling has also been found to play an important role in inhibition of neighboring neurons. Depending on the location and identity of the neurons, various mechanisms have been found to underlie ephaptic inhibition. In one study, newly excited neighboring neurons interfered with already sustained currents, thus lowering the extracellular potential and depolarizing the neuron in relation to its surrounding environment, effectively inhibiting the action potential's propagation.