How do signals from nerve endings retain information about their origins as they travel to the brain?

So, say the nerve endings in your fingertip send out a signal in response to a pin prick. That signal gets passed up the branches of the nervous system, through the spinal cord and into the brain, right? What is there about that signal that the brain ultimately receives that enables the brain to localize the exact source of the signal? Is that information encoded into the signal? Or is there a dedicated line of transmission from every nerve ending all the way to the brain?