Fig. 3.

Serotonin in the adult Drosophila brain. (A) In this slightly oblique frontal image, depth is encoded from anterior to posterior as blue to red in 100 steps (0–125 relative units). Serotonergic neuron clusters are labeled (see Table 2 for description of each cluster and explanation of abbreviations). Also evident are innervations of the serotonergic neurons in the fan-shaped body (fb) and elsewhere. In B and C, confocal image sections including the fan-shaped body (fb) and rostral were used to generate the anterior images on the left. Different brains were imaged from the posterior to provide the caudal information. (B) Ddc-GAL4 drives expression of UAS_GAL4-GFP expression in a subset of the serotonergic neurons and two groups of nonserotonergic cells (described in Results). The anterior labeling has Ddc-GAL4/serotonin coexpression in a subset of the lp2, amp, alp (not shown), se1, se2, and se3 cells. Posterior Ddc-GAL4 / serotonin coexpression is detected in a subset of the pmp and plp cells. (C) TH-GAL4 drives UAS_GAL4-GFP expression in a distributed set of cells that do not overlap in expression with the serotonergic neurons. The white colocalization signal in the anterior medial ventral brain is an artifact of flattening these optical sections. (D) TH-GAL80 can effectively suppress TH-GAL4-driven UAS_GAL4-GFP expression. (Scale bar in A: 50 μm; applies to all.)