What processes cause the recovery of the nerve cell after hyperpolarisation? It can't be the sodium/potassium pump because it pumps 3 sodiums out and 2 potassiums in thus lowering the cell potential. The only reason I can think of is because the inside is negative, so there is electrical gradient for sodium ions? It must be to do with the relative permeabilities but I can't find a list of permeabilities of different ions at different voltages? Also, when you voltage clamp the membrane potential to about -120mV, there is a small inward current, which ion is responsible for that? I've done some reading and I think it could be because of the gradual depolarisation due to K+ channel inactivation, maybe there is also a 'funny' current as seen in cardiac pacemaker cells?