Excitation threshold of a neuron

Question

Describe the excitation threshold of a neuron? How does this threshold associate to the “all-or-nothing” rule of neural transmission?

Answer 1

The excitation threshold of a neuron is the depolarization level which must be caused by a stimulus to be transmitted as neural impulse. This value is around –50 mV.

The transmission of neural impulse all along the neuronal membrane follows an all-or-nothing rule: or it occurs with maximum intensity or nothing occurs. Always and only whenever the excitation threshold is arrived at the depolarization continues and the membrane reaches its utmost possible positive polarization, around +35 mV. When the excitation threshold is not reached nothing occurs.