ScerGAL4SerT.3 drives expression in 1-2 neurons in the SE1, LP1 and IP serotonergic neuron clusters. The IP neuron projects to the superior medial protocerebrum, posterior lateral protocerebrum and optic lobe, while the SE1 neurons innervate the subesophageal zone and the LP1 neuron is intrinsic to the ventrolateral protocerebrum.