A note for Lesson no. 2, "Your Brain Is a Network," in Lisa Feldman Barrett.
Some context from page 33 is:
...you have a more frugal wiring arrangement that is sort of like the global air-travel system.
My airport metaphor, like all metaphors, has limitations. Signals in the brain do not pass unchanged from neuron to neuron like planes pass from airport to airport. Every neuron receives information from thousands of other neurons, so a signal from one neuron to another is modulated by thousands of other signals.