Pain and itch processing by subpopulations of molecularly diverse spinal and trigeminal projection neurons
Racheli Wercberger, João M. Bráz, Jarret A.P. Weinrich, Allan I. Basbaum
Abstract
Significance To generate modality-specific percepts (e.g., pain vs. itch), the brain must interpret the activity that arises from the output cells (projection neurons) of the dorsal horn of the spinal cord, which receive and then transmit pain- or itch-provoking stimuli. However, neither the extent to which projection neurons relay modality-specific messages nor the molecular makeup of these neurons is clear. Here, we report that the projection neurons are, in fact, diverse, not only molecularly but also functionally. By focusing on genes expressed by projection neurons within the neurokinin-1 receptor (NK1R) and non–NK1R-expressing populations, we also demonstrate considerable functional heterogeneity among these subsets, including nociceptive (pain)-specific, pruriceptive (itch)-specific, and polymodal (both pain and itch) subsets of projection neurons.