Figure 8.

Odor response properties of the dopaminergic neurons innervating the lobes after pairing odor with electric shock. (A) Training paradigms including naïve, forward, backward, CS-only, and US-only. For each fly, odor was presented for 3 s at 5 min prior to conditioning and the calcium responses were monitored. The odor was presented again at 10 min after conditioning and the calcium responses were again monitored. Flies were trained between the Pre and Post presentations of odors and the percentage ratio of the Post/Pre response determined and plotted in panels (B,C). (B) Responses in the upper stalk and lower stalk/junction 10 min after conditioning with 0.3% octanol (OCT) and 0.01 mA electric shock. n = 10–21 for each group. Data represents mean ± SEM. *Indicates significant difference (p < 0.0001). Forward, backward, and CS-only conditioning each reduced the subsequent calcium response to odor in the upper stalk region. There were no significant differences observed due to conditioning in the lower stalk/junction region, although there was a trend for an increased response with forward and US-only conditioning. (C) Responses in the upper stalk, lower stalk/junction, α lobe tip, and α′ lobe tip after conditioning with 0.1% methylcyclohexanol (MCH) and 0.01 mA electric shock. n = 6–12 for each group. Data represents mean ± SEM. *Indicates significant difference (p < 0.005). The response properties due to conditioning with MCH in the upper stalk and lower stalk/junction were similar to those observed with OCT, with decreased responses in the upper stalk after forward and CS-only conditioning, and no significant differences in the lower stalk/junction. The α and α′ lobe tips responded to conditioning in ways that were similar to the upper stalk responses, with reduced responses to forward, backward, or CS-only conditioning that were either significant or were trends that failed to reach significance.