Excitation threshold of neuron

Question

What do you mean by the excitation threshold of a neuron? How this threshold is related to the “all-or-nothing” rule of neural transmission?

Answer 1

Excitation threshold of neuron is defined as the depolarization level which should be caused by the stimulus that is to be transmitted as a neural impulse. This value is around –50 mV. The transmission of neural impulse all along the neuronal membrane follows “all-or-nothing rule” or it takes place with the maximum intensity or nothing occurs. Always and only when the excitation threshold is achieved depolarization continues and the membrane reaches its higher possible positive polarization, around +35 mV. In case excitation threshold is not attained nothing takes place.