Threshold potential is a state of depolarisation at which _____.
All of the above
Threshold potential can be defined as the state of depolarisation at which an action potential is sure to fire. When a neuronal membrane depolarizes to about -55mV, the voltage gated Na+ channels open. Once these channels open there is no preventing an action potential because these channels, regulated by voltage open causing a positive cascade i.e. opening of these channels depolarises the membrane further by allowing Na+ ions inside the cell and more depolarisation opens more voltage gated sodium channels.