Nervous system functions rely on complex circuits which precisely wire many distinct types of neurons into highly organized networks. The formation of this enormously intricate circuitry during embryogenesis is a fascinating question. The knowledge of brain wiring mechanisms will certainly help repair disconnected circuits caused by traumatic injury or neurogenerative conditions. Neuronal axons use a highly sensitive structure at their tips, the growth cones, to detect gradients of guidance cues. Although many axon guidance molecules have been discovered, how the growth cones use them to find their way in the developing brain is still unknown. We discovered that the same signaling pathways that set up polarity of epithelial cells mediate growth cone turning in response to gradients of Wnts, a class of morphogens which play pivotal roles in setting up wiring diagrams. I will talk about a new study on how two major polarity signaling systems interact with each other to convey directionality to axons and how they may amplify the asymmetric signal to cause turning. This type of signaling logic may be a common compponent in call cases of axon guidance.