FIG. 1.

Electrical circuit representation of two cells with ephaptic and gap junction coupling. Intracellular nodes along lateral segments (with voltages $V_1$ and $V_2$) are coupled via gap junction resistance ( $R_{gap}$). Extracellular cleft potential $V_{cl}$ is governed by the two disk junctions and cleft resistance $R_{cl}$. Junctional and lateral membranes are governed by both capacitances ( $C_j$ and $C_{lat}$, respectively) and ionic currents ( $I_{j,i}$ and $I_i$, respectively, for $i=1,2$).