The difference in electrical potential energy between a neuron and the surrounding extracellular fluid can be called the .

membrane potential.  

Explanation:

The difference in electrical potential energy between a neuron and the surrounding extracellular fluid can be called the membrane potential.  Membrane potential is generally negative with the outside. It is due to this potential difference that provides energy for the signal flow. And the difference between the electrical charge difference is called resting potential.

where is the circuit diagram ?

an electric circuit