Progress in realizing the promise of microarrays in systems neurobiology.

The power of microarrays in neuroscience has been challenged by the cellular heterogeneity and complexity of the central nervous system. In this issue of Neuron, Arlotta, Molyneaux, and colleagues have developed a technique combining retrograde labeling, flow cytometry, and microarrays to purify and molecularly characterize a specific population of neurons from the brain, focusing here on cortical projection neurons. We discuss these findings and the implications of this development for both systems and molecular neuroscience.