In order to establish a metaphor that can explain how neurons work, we need to establish a baseline or basic definition. A working definition of a neuron can be: "Neurons (also known as neurones, nerve cells and nerve fibers) are] electrically excitable cells in the nervous system that function to process and transmit information." The neuron is the relayer of messages related to sensory perception and transmits this information to the central nervous system. Neurons "send signals to the spinal cord and brain." In this light, the neuron is not directly in command, but rather functions in a serving capacity to relay information to those in charge.
One metaphor that can apply here is a warfighting metaphor. Direct actions on the battlefield are relayed by military officers to those in the position of command. For example, the squad leaders are like the neurons who are able to effectively convey to those higher up the military command chain what is happening on the ground. The squad leaders see what is happening, just as the neuron is able to interpret signals, sending them to the spinal cord and brain. The squad leader is able to report about actions on the ground, actionable intelligence, and enable those in the position of command such as generals what actions can be taken given what is on the ground. The squad leaders transmit information in a similar way as the neurons that send information to the central nervous system for processing. The metaphor is steeped in the idea that data must be transmitted in order for it to make sense. The squad leader on the ground in war becomes a metaphor for the neuron.
Another metaphor that can describe the neuron comes from the film, Mean Girls. In the film, the most dominant clique in the high school, the Plastics, is run by the "Queen Bee," Regina George. In the position of central power, Regina is able to make the rules that others in the clique must follow. She also plays a decisive role in who is popular and who is not. Regina makes these decisions based on information relayed to her by her "lieutenant," Gretchen Wieners. When she is first seen, Damian, an outsider, describes that her hair is so lush because "it is filled with other people's secrets." Gretchen's primary responsibility is to relay valuable information to Regina, who decides what to do with it. Gretchen's function is to interpret and absorb information, sending it up to Regina. Gretchen is quite excitable in her role, always wanting to serve Regina in an information capacity. Her value to the Plastics is one of information and obtaining it, relaying it in an excitable manner. Gretchen can represent a metaphorical relationship to a neuron. The neuron collects information in an "excitable" manner, similar to Gretchen, and sends that information to the central nervous system, who, in this metaphor, would be Regina. Thus, in the "Mean Girls" metaphor of the nervous system, Gretchen would be the neuron.