Video 12.3m Silent Stimulated. The electrode enters around cell 19. After an initial volley of action potentials, the resting potential settles down at about −50 mV and is silent. After a 2 s injection of hyperpolarizing current, action potentials fire. During a small 2 s depolarizing current, action potentials fire. After this, the neuron starts to depolarize and fires more action potentials, after which the recording is lost.