Other dorsal interneurons in zebrafish and mice. (A) In zebrafish, four classes of dorsal interneuron have been identified: glutamatergic commissural primary ascending (CoPA, red), glycinergic commissural secondary ascending (CoSA, dark blue), glycinergic commissural longitudinal ascending (CoLA, green), and glycinergic dorsal longitudinal ascending (DoLA, yellow). CoPA neurons drive touch-mediated larval escape. (B) In mice, dorsal neurons are divided into seven classes: dI1-5, dILA and dILB. The glutamatergic dI1 class (yellow) subdivides into ipsi- and contralateral populations. Little is known about the dI2 class (light green). The dI3 class (dark blue) receives cutaneous afferent input and excites motor neurons (green). The dI4 class subdivides according to sensory modality: the NPY subclass (dark purple) is associated with mechanical itch, BHLHB5 (medium-dark purple) with chemical itch, and DYN (medium-light purple) with nociception. RORβ neurons (light purple) gate sensory afferent transmission. They also include dILA (light purple-pink) and dILB (light pink-brown) classes. dI5 neurons associated with scratch (dark brown) are located in laminae I/II, and with paw withdrawal reflex (medium brown) in laminae II/III. RORα neurons (light brown) receive descending motor commands and project onto motor neurons, and function in corrective motor adjustments.
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