Neuronal diversity in the somatosensory system: bridging the gap between cell type and function

A recent flurry of genetic studies in mice have provided key insights into how the somatosensory system is organized at a cellular level to encode itch, pain, temperature, and touch. These studies are largely predicated on the idea that functional cell types can be identified by their unique developmental provenance and gene expression profile. However, the extent to which gene expression profiles can be correlated with functional cell types and circuit organization remains an open question. In this review, we focus on recent progress in characterizing the sensory afferent and dorsal horn neuron cell types that process cutaneous somatosensory information and ongoing circuit studies that are beginning to bridge the divide between cell type and function.