Question

A neuron has a resting membrane potential of -70 mV; it’s trigger threshold for firing an action potential is -50 mV. Two competing signals arrive simultaneously in the trigger zone: one is a depolarizing stimulus of +40 mV, the other a hyperpolarizing stimulus of -25 mV. Will the neuron fire an action potential after integrating these signals? Why?

Answer 1

No. the neuron will not fire an action potential after integrating these signals

the stimulus at the trigger zone =depolarizing stimulus + hyperpolarizing stimulus=+40 mV+ (-25 mV)= +15 mV

the stimulus generated at the trigger zone due to the depolarizing stimulus and the hyperpolarizing stimulus is only 15 mV, the resting membrane potential is -70 mV it has to reach up to -50 mV, for the neuron to fire but here when a stimulus of 15 mV reaches the trigger zone the membrane potential becomes -70+15=-55 mV so the neuron cannot fire.