Excitatory SST neurons in the medial paralemniscal nucleus control repetitive self 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 reinforce-ment 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 neu-rons as an interface linking the stress and reward systems in mice.

Automated summary

The study investigates the neurobiological mechanism of repetitive behaviors in mice and identifies the role of MPLSST neurons in self-grooming and anxiety regulation. Activation of MPLSST neurons promotes rewarding effects and activates dopamine neurons, while loss of function impairs self-grooming and post-stress anxiety alleviation. The findings suggest a dual role of the CeA-MPLSST-VTA-DA circuit in stress and reward processing.