Fig. 6

Schematic model for serotonin and its receptor 5-HT2B on autism-like behaviors. The Drosophila brain with main areas is in frontal view. Each color represents a distinct type of neuron: dFB (orange); per (dark green); pdf (blue); or83b (light green); MB, mushroom body and EB, ellipsoid body (dark gray). Normally, serotonin synthesized and released from presynaptic neurons located in the dorsal fan-shaped body binds to 5-HT2B receptors and activates G proteins postsynaptically, which maintains normal social behavior in Drosophila. When reduced in dFB neurons, 5-HT2B receptors could not activate downstream G proteins, leading to stereotyped behavior and abnormal social interaction in flies