Fig. 4.

Manipulating the serotonergic system reduces memory performance. (A) Flies in which the TeTxLC was expressed in a set of CNS neurons, including the serotonergic neurons, showed a strong reduction in place memory [H (2, n = 286) = 14.5, P = 0.0007, multiple comparisons indicate significant differences between Ddc-GAL4;TH-GAL80/UAS_GAL4-TeTxLC and both Ddc-GAL4;TH-GAL80/+ and UAS_GAL4-TeTxLC/+ performances (*, P < 0.05)]. (B) Tests for the ability to sense and avoid a 41°C high-temperature source in the thermosensitivity assay found no significant differences between the genotypes tested [H (2, n = 210) = 1.20, P = 0.55]. (C) Adult flies fed am-W, reducing serotonin levels (36), had a significant difference in memory performance compared with flies fed on the media alone (sham) and flies fed am-Y, altering dopamine levels [H (2, n = 316) = 10.9, P = 0.004; multiple comparisons indicate significant differences between am-W-treated and both am-Y- and sham-treated flies (*, P < 0.05)]. (D) Tests for the ability to sense and avoid a 41°C high-temperature source in the thermosensitivity assay found no significant differences between the treatment groups (U test: Z = 0.77, P = 0.44, n = 190). Flies fed am-Y were not tested (ND) in the thermosensitivity assay. The values represent means, and error bars are SEMs.