Question

A neuron is found to have a resting membrane potential of −20mV and a threshold stimulus of −10mV. A researcher applies the following voltages to the neuron:

Trial 1 4mV

Trial 2 6mV

Trial 3 8mV

Trial 4 12mV

On what trial does the researcher generate an action potential in the neuron?

Answer 1

Action potentials work on an all-or-none basis. This means that an action potential is either triggered, or it isn’t – like flipping a switch. A neuron will always send the same size action potential.

Not all stimuli can cause an action potential. Adequate stimulus must have a sufficient electrocal value which will reduce the negativity of the nerve cell to the threshold of the action potential. In this manner, there are subthreshold, threshold, and suprathreshold stimuli.

Subthreshold stimuli cannot cause an action potential. Threshold stimuli are of enough energy or potential to produce an action potential (nerve impulse). Suprathreshold stimuli also produce an action potential, but their strength is higher than the threshold stimuli.

Here in this case the researcher will generate an action potential only in trial 4.