Exploratory rearing is governed by hypothalamic MCH cells according to the locus coeruleus

Exploration is essential for survival because it allows animals to gather information about their environment. Rearing is a classic exploratory behavior, during which an animal transiently stands on its hind legs to sample its environment. It is widely observed in common lab conditions as well as in the wild, yet neural signals and circuits underlying this fundamental component of innate behavior remain unclear. We examined behavioral correlates of activity in hypothalamic MCH-producing neurons (MNs) - a recently characterized but still poorly understood neural type - and found that MN activation co-occurs with exploratory rears in mice. Complementary optogenetic and pharmacological manipulations indicated that MN activity selectively promotes rearing via G-protein coupled MCHR1 receptors. Furthermore, we show in vivo that activation of the locus coeruleus noradrenergic neurons rapidly inhibits MNs and suppresses rearing through MCHR1-dependent pathways. Overall, these findings define a subcortical neural module which both tracks and controls exploratory rearing.