Figure 6. Taste projection neurons are essential for conditioned taste aversion.
(A) Schematic of aversive taste memory protocol experiments with flies expressing Shits in TPN1, TPN2 or TPN3. Flies were initially presented with 500 mM sucrose (pre-test) and only flies that showed reliable PER were included for the remainder of the experiment. Next, flies were presented with sucrose on their legs and their proboscis was touched with bitter 50 mM quinine upon PER (pairing). Finally, flies were presented with sucrose to the legs in 5 min intervals to test memory after pairing. (B) Aversive taste memory upon conditional silencing of TPN1 shows unimpaired memory at restrictive (30°C) temperature (red) when compared to permissive room temperature flies (gray), indicating TPN1 is not required for memory. (C) Conditional silencing of TPN2 shows impaired memory at restrictive temperature, specifically in tests after pairing, suggesting TPN2 is required for memory. (D) Conditional silencing of TPN3 produces defects during training and post-training, showing TPN3 is required for memory. (E) Schematic of aversive taste memory protocol experiments with flies expressing CsChrimson in TPN3. Experiments were conducted as described in A, except during pairing: proboscis stimulation with quinine was replaced with red light stimulation (i.e. activation of TPN3). (F) Activating TPN3 with CsChrimson, which replaces bitter application during training, serves as a US to produce robust learning. For B,C,D,F, error bars are 95% CI; for each CS presentation, the difference between the control and experimental conditions (e.g. gray and colored data points) were tested with Fisher’s Exact Tests with Bonferroni adjusted alpha levels of *p<0.005 (0.05/10), **p<0.001 (0.01/10), ***p<0.0001 (0.001/10).
Figure 6—figure supplement 1. Memory experiment controls.
