Excitatory SST neurons in the medial paralemniscal nucleus control repetitive self-grooming and encode reward.

The use of body-focused repetitive behaviors (BFRBs) is conceptualized as a means of coping with stress. However, the neurological mechanism by which repetitive behaviors affect anxiety regulation is unclear. Here, we identify that the excitatory somatostatin-positive neurons in the medial paralemniscal nucleus (MPLSST neurons) in mice promote self-grooming and encode reward. MPLSST neurons display prominent grooming-related neuronal activity. Loss of function of MPLSST neurons impairs both self-grooming and post-stress anxiety alleviation. Activation of MPLSST neurons is rewarding and sufficient to drive reinforcement by activating dopamine (DA) neurons in the ventral tegmental area (VTA) and eliciting dopamine release. The neuropeptide SST facilitates the rewarding impact of MPLSST neurons. MPLSST neuron-mediated self-grooming is triggered by the input from the central amygdala (CeA). Our study reveals a dual role of CeA-MPLSST-VTADA circuit in self-grooming and post-stress anxiety regulation and conceptualizes MPLSST neurons as an interface linking the stress and reward systems in mice. [Display omitted] • MPLSST neurons promote self-grooming and show grooming-related neuronal activity • MPLSST neurons are glutamatergic and encode reward value • The neuropeptide SST facilitates the rewarding impact of MPLSST neurons • Inhibition of MPLSST neurons impairs post-stress anxiety regulation Sun et al. identify a CeA-MPLSST-VTADA circuit controlling self-grooming and post-stress anxiety alleviation by activation of the reward system in mice. This study provides insights into how repetitive behavior-related neurons connect to and influence emotion regulation-related neurons, with significant implications for the neuropsychological mechanisms of body-focused repetitive behaviors (BFRBs). [ABSTRACT FROM AUTHOR]