In the manuscript submitted to e-Life (Dorsal raphe nucleus to anterior cingulate cortex 5-HTergic neural circuit modulates consolation and sociability), all data are represented as the mean ± SE. All data were assessed for normality using a one-sample Kolmogorov-Smirnov test, and the Levene's test was used to confirm homogeneity of variance. Comparisons between two groups were performed by unpaired or paired t tests. Comparisons among three or more groups of different animals were performed using one-way ANOVA. Two-way ANOVAs or two-way repeated measures ANOVAs were used to compare multiple groups under multiple testing conditions when appropriate. Post hoc comparisons were conducted using Tukey. To confirm the significance and calculate the effect size, Bayesian t test (paired or unpaired) and Bayesian ANOVA were conducted for all the comparisons using default priors. For more detailed information about the Bayesian test, please refer to Dr. Keysers's work (Keysers et al., 2020). The data were analyzed using JASP 14.0 (https://jasp-stats.org/) and are presented as the mean ± SE. The significant level was set at P < 0.05. The detailed analysis method in each figure and the statistical quantifications are presented in Supplementary 2. Citations: Keysers, C., Gazzola, V., Wagenmakers, E.J., 2020. Using Bayes factor hypothesis testing in neuroscience to establish evidence of absence. Nature neuroscience 23, 788-799. Funding provided by: National Natural Science Foundation of ChinaCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100001809Award Number: 31970424, 31670421, 31372213 and 31772473Funding provided by: Natural Science Basic Research Program of Shaanxi ProvinceCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100017596Award Number: 2018JM3032

Consolation is a common response to the distress of others in humans and some social animals, but the neural mechanisms underlying this behavior are not well characterized. By using socially monogamous mandarin voles, we found that optogenetic or chemogenetic inhibition of 5-HTergic neurons in the dorsal raphe nucleus (DR) or optogenetic inhibition of 5-HT terminals in the anterior cingulate cortex (ACC) significantly decreased allogrooming time in the consolation test and reduced sociability in the three-chamber test. The release of 5-HT within the ACC and the activity of DR neurons were significantly increased during allogrooming, sniffing and social approaching. Finally, we found that the activation of 5-HT1A receptors in the ACC was sufficient to reverse consolation and sociability deficits induced by the chemogenetic inhibition of 5-HTergic neurons in the DR. Our study provided the first direct evidence that DR-ACC 5-HTergic neural circuit is implicated in consolation-like behaviors and sociability.