Q. What is the excitation threshold of a neuron? How does this threshold relate to the "all-or-nothing" rule of the neural transmission?
The excitation threshold of a neuron is the depolarization level that must be caused by a stimulus to be transmitted as a neural impulse this value is about -50 mV. The transmission of the neural impulse along the neuronal membrane obeys an all-or-nothing rule or nothing happens or it happens with maximum intensity. Always and only when the excitation threshold is reached the depolarization continues and the membrane reaches its maximum possible positive polarization about +35 mV if the excitation threshold isn't reached nothing happens.