The serotonin system modulates a wide variety of emotional behaviors and states, including reward processing, anxiety, and social interaction. To reveal the underlying patterns of neural activity, we visualized serotonergic neurons in the dorsal raphe nucleus (DRN^5-HT) of mice using miniaturized microscopy during diverse emotional behaviors. We discovered ensembles of cells with highly correlated activity and found that DRN^5-HT neurons are preferentially recruited by emotionally salient stimuli as opposed to neutral stimuli. Individual DRN^5-HT neurons responded to diverse combinations of salient stimuli, with some preference for valence and sensory modality. Anatomically defined subpopulations projecting to either a reward-related structure (the ventral tegmental area) or an anxiety-related structure (the bed nucleus of the stria terminalis) contained all response types but were enriched in reward- and anxiety-responsive cells, respectively. Our results suggest that the DRN serotonin system responds to emotional salience using ensembles with mixed selectivity and biases in downstream connectivity.

血清素系统调节多种情绪行为和状态，包括奖励处理、焦虑和社交互动。为了揭示神经活动的潜在模式，我们使用微型显微镜观察了小鼠中缝背核（DRN ^{5-HT ）在不同情绪行为期间的血清素能神经元。}我们发现了具有高度相关活性的细胞群，并发现 DRN ^5-HT神经元优先被情感显着刺激而不是中性刺激所招募。单个 DRN ^5-HT神经元对显着刺激的不同组合做出反应，对效价和感觉方式有一定的偏好。解剖学上定义的亚群投射到奖励相关结构（腹侧被盖区）或焦虑相关结构（终纹床核）包含所有反应类型，但分别富含奖励反应和焦虑反应细胞。我们的结果表明，DRN 血清素系统使用具有混合选择性和下游连接偏差的整体来响应情绪显着性。