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Food intake behavior is regulated by a network of appetite-inducing and appetite-suppressing neuronal populations throughout the brain. The parasubthalamic nucleus (PSTN), a relatively unexplored population of neurons in the posterior hypothalamus, has been hypothesized to regulate appetite due to its connectivity with other anorexigenic neuronal populations and because these neurons express Fos, a marker of neuronal activation, following a meal. However, the individual cell types that make up the PSTN are not well characterized, nor are their functional roles in food intake behavior. Here, we identify and distinguish between two discrete PSTN subpopulations, those that express tachykinin-1 (PSTN Tac1 neurons) and those that express corticotropin-releasing hormone (PSTN CRH neurons), and use a panel of genetically encoded tools in mice to show that PSTN Tac1 neurons play an important role in appetite suppression. Both subpopulations increase activity following a meal and in response to administration of the anorexigenic hormones amylin, cholecystokinin (CCK), and peptide YY (PYY). Interestingly, chemogenetic inhibition of PSTN Tac1 , but not PSTN CRH neurons, reduces the appetite-suppressing effects of these hormones. Consistently, optogenetic and chemogenetic stimulation of PSTN Tac1 neurons, but not PSTN CRH neurons, reduces food intake in hungry mice. PSTN Tac1 and PSTN CRH neurons project to distinct downstream brain regions, and stimulation of PSTN Tac1 projections to individual anorexigenic populations reduces food consumption. Taken together, these results reveal the functional properties and projection patterns of distinct PSTN cell types and demonstrate an anorexigenic role for PSTN Tac1 neurons in the hormonal and central regulation of appetite. 

Abstract Despite its increased prioritization over the past several decades, democracy remains an elusive feat for many nations. This is due, in part, to a recent uptick in hybrid regimes, which possess qualities of both democracy and authoritarianism simultaneously. Among others, one especially salient explanation for hybrid formation is democracy aid itself, which often engenders superficial democratization while masking ongoing authoritarian practices. Still, despite considerable research examining how various factors—including aid—impact hybrid regimes, relatively little headway has been made. This is due primarily to continued disagreement over how to best measure and situate hybrids within the broader democracy literature. In this review, I demonstrate the role sociology can play in addressing this issue while advancing research on democracy, hybrids, and aid in a productive way. I argue that using sociological theories explaining the spread of global norms—such as democracy—to analyze hybrid regimes will facilitate improved understanding of democracy and the factors which shape it across the social sciences.