Fig. 10. Further evidence of the different mechanisms of generation of V₁ and V₂ can be obtained by fish curarization, which blocks transmission at the neuro-electrocyte junction. The dose was adjusted to be just enough to stop breathing but not enough to completely block the discharge. (A) The head-to-tail equivalent electromotive force of a fish in control (black) and curarized (red) conditions. (B) The spatial profile of the first negative deflection in control (black) and curarized (red) conditions. Note the differential effect on V₁ and V₂; V₁ is the less affected component because it is generated by the subthreshold activation of the rostral membranes of doubly innervated electrocytes. V₄ is absent because the amount of current generated by V₃ is subthreshold for generating an action potential at the rostral faces of single innervated electrocytes.