Conserved genetic signatures parcellate cardinal spinal neuron classes into local and projection subsets

Neuronal identities Neurons of the mouse spinal cord can be identified by any of several metrics, including what neurotransmitters they use, what cells they connect to, where they are located, and what neuroprogenitor gave rise to them. Osseward et al. generated a different metric, genetic signatures, and identified classes of local and projection neurons that were otherwise heterogeneous by other classification systems. With this focus on a cell's genetic signature, its neurotransmitter phenotype, which is accessible by a variety of transcriptional routes, can be seen as a parallel to convergent evolution in development. Science , this issue p. 385