NEURON {
   POINT_PROCESS Gap
   POINTER vgap
   RANGE r, i   
   NONSPECIFIC_CURRENT i
}

PARAMETER { r = 1e10 (megohm) }

ASSIGNED {
   v (millivolt)
   vgap (millivolt)
   i (nanoamp)
}

BREAKPOINT { i = (v - vgap)/r }