A. A schematic view of an idealized action<unk>  illustrates its various phases as the action<unk>  passes a point on a cell membrane. B. Actual recordings of action<unk> s are often distorted compared to the schematic view because of variations in electrophysiological techniques used to make the recording. In electrophysiology, the<unk>  is the critical level to which a membrane<unk>  must be depolarized to initiate an action<unk> . In neuroscience,<unk> s are necessary to regulate and propagate signaling in both the central nervous system (CNS) and the peripheral nervous system (PNS). Most often, the<unk>  is a membrane<unk>  value between –50 and –55 mV, but can vary based upon several factors. A neuron's resting membrane<unk>  (–70 mV) can be altered to either increase or decrease likelihood of reaching<unk>  via sodium and potassium ions. An influx of sodium into the cell through open, voltage-gated sodium channels can depolarize the membrane past<unk>  and thus excite it while an efflux of potassium or influx of chloride can hyperpolarize the cell and thus inhibit<unk>  from being reached.
Threshold potential
End-plate potential
Dark adaptation threshold
Intermuscular coherence
Threshold of pain
Frequency following response
Extraction ratio
Peak kilovoltage