Formation of sensory maps: New tools reveal novel insights into neural development.

The development of functional neural circuits depends on the navigation of neurites (axons and dendrites) through spatially complex and molecularly diverse environments to their appropriate targets. How these processes maneuver through dense surroundings to reach their targets is a long-standing question in neuroscience. Studies of sensory systems have been especially enlightening for identifying cues that underlie connectivity due to their organization as stereotyped neural maps. Recent advances in imaging, connectomics, and genomics have profoundly deepened our understanding of these processes and uncovered new mechanisms regulating circuit development. In this review, we discuss studies of Drosophila sensory systems that provide new insights into axon and dendritic targeting, partner identification and selection, and subcellular refinement. We highlight related or divergent findings in other systems and provide an outlook for future studies.