How does neuron stimulation work? Neurons are excited via an external electrode by passing current through it. A neuron at rest is at -70 mV, it needs additional charge amounting to around 15 mV to initiate an action potential. But the external electrode only gives electrons, which are negatively charged, how can they increase the potential inside the neuron? Does the electrode provide charge to the outside of the membrane of the neuron?
The electric field of an external electrode provokes the opening of sodium channels, which in turn has the effect that the positive charged sodium ions travel into the cell body and invoke the wanted change to the Membran potential…

reference: Simulation Neuronaler Netze [("Simulation of Neural Networks")] / Andreas Zell. - Bonn; Paris; Reading, Mass [u.a.]: Addison-Wesley, 1994, first edition