The human nervous system is a complex network of cells, all working together. The intense specialization of this network starts during development, when cells must talk to each other to carefully coordinate wiring up neural circuitry.
The wiring relies on the neural cells themselves. They have rounded cell bodies surrounded by short spines called dendrites, and longer tails, called axons. Each neuron only has one axon, which connects to dendrites on other nerve cells.
Sending that axon to the right place—a process called neural pathfinding—is the subject of an entire field of study. Researchers have identified a variety of specialized signaling molecules that instruct neurons on where they should go. It's not always clear, however, how these signaling networks interact to send axons to the right place. A recent paper published in Science helps to clarify some of these unknowns.