Figure 5.

R2/R4m Neurons in the Ellipsoid Body Are Responsible for Overcoming the Loser Effect

(A) Expression patterns of C819-Gal4/UAS-mCD8:GFP revealed strong signals in the R2/R4m neurons of the EB region.

(B) Activation of C819-Gal4-labeled R2/4m neurons promoted the attack intensity of the losers (n = 14–22).

(C) Inhibition of synaptic transmission of C819 neurons decreased the attack intensity of socially isolated males (n = 23–25).

(D) Enhanced 5-HT1B receptor level in R2/R4m neurons restored aggression in losers (n = 22–24).

(E) 5-HT neurons were visualized by Tph > myrGFP signals (green). The trans-Tango approach revealed the postsynaptic neurons in AL, SOG, MB, EB, and FB (mtdTomato signal, purple).

(F) The direct application of serotonin hydrochloride increased the calcium level in C819 neurons. The confocal images showed the GCaMP signals in the R2/R4m neurons of the EB region before 5-HT delivery (F1) and after 5-HT delivery (F2). Panel F3 shows the corresponding cell clusters in this region, which were identified according to the RFP signal (red). Panel F4 shows the overlay staining patterns of F2 and F3.

(G) Quantification of mean GCaMP signals (normalized to RFP signals) in C819 neurons before and after 5-HT application (n = 13).

(H and I) Losers displayed lower calcium levels in C819 neurons than the corresponding winners (n = 20–21). The Kruskal-Wallis test was performed for (B)-(D), and the paired t test was performed for (G) and (I). ∗P < 0.05; ∗∗∗P < 0.001. Scale bar, 100 μm.

See also Figure S8.