Excitation threshold of neuron

Question

What is excitation threshold of the neuron? How does this threshold relate to “all-or-nothing” rule of neural transmission?

Answer 1

Excitation threshold of the neuron is depolarization level which should be caused by the stimulus to be transmitted as a neural impulse. This value is about –50 mV.

The transmission of neural impulse along neuronal membrane obeys the all-or-nothing rule: or it takes place with maximum intensity or nothing takes place.

Always and only when the excitation threshold is reached depolarization continues and membrane reaches its maximum probable positive polarization, about +35 mV. If excitation threshold is not reached nothing takes place.