I'm referring to the overlapping sigmoidal curves that are used to describe the gain-of-function mechanisms. I understand the activation curve, but I can't seem to get my head around the inactivation curve. Any help at all would be very much appreciated, whether that is an explanation or pointing to one in the literature. It would also be helpful if you could explain the holding potential, depolarising voltage steps, and pre-pulse vs test pulse. Thank you in advance!