Figure 2.

Activation of 5-HT Neurons Promotes Fighting of Losers Against Winners

(A) Schema of optogenetic activation of a Tph > PACα loser before pitting it against the familiar winner.

(B) The Tph > PACα losers treated with light showed a higher attack intensity (n = 57 and 66).

(C) Light treatment of the Tph > PACα losers induced more losers to fight against the familiar winners than those without light treatment (n = 57 and 66).

(D) In total, 29% of the losers with activated 5-HT neurons eventually reversed the winner-loser relationship of Round 1 (n = 57 and 66).

(E) Schema of the experimental procedure to stimulate losers in situ.

(F) Optogenetic stimulation increased the attack intensity of Tph > PACα losers to their winners in situ (n = 28–34).

(G) Optogenetic stimulation increased the retaliation frequency of Tph > PACα losers to their winners (n = 28–34).

(H) Optogenetic stimulation increased the reversal frequency of Tph > PACα losers against their winners (n = 28–34). The Mann-Whitney test was performed for (B), Fisher's exact test was performed for (C) and (D), the Kruskal-Wallis test was performed for (F), and the chi-square test was performed for (G) (two-tailed χ2 = 58.16, df = 2) and (H) (two-tailed χ2 = 44.02, df = 2). ∗∗P < 0.01; ∗∗∗P < 0.001.

See also Figures S1–S4.