It's a brain.

"Is that somebody's brain?" she asks. I look up at her, rolling her mouth and smiling down. I look at the map. It's not a brain, clearly; it's a map. Can't she see the rivers and highways and interchanges? But I see how it could look like a brain, like if all roads were twisted neurons, pulling your emotions from one place to another, bringing the city to life. A working brain is probably a lot like a map, where anybody can get from one place to another on the freeways. It's the nonworking brains that get blocked, that have dead ends, that are under construction like mine. "Yeah," I say, nodding up at her. "Yeah. That's exactly what it is. It's a brain."