inhibition reduces odor-evoked firing frequency. For each fly strain, CO2 and a 10-4 dilution of ethyl acetate were used to evoke spike activity from ab1C or ab1A neurons respectively. Spike frequency in Gal80ts20/+; UAS-PTX/+ and Or83b-Gal4/+ control strains do not decrease (p > 0.5) at 32°C compared to 18°C. Gal80ts20/Or83b-Gal4; UAS-PTX/+ flies have a significantly (p < 0.0001) lower ethyl acetate evoked ab1A spike frequency in the absence of PTX expression (18°C) than in the presence of PTX expression (32°C), whereas CO2-induced single unit responses in the ab1C neuron was not unaffected (p > 0.8). For each genotype and temperature, responses from at least 8 ORNs from minimum 4 flies were analyzed. Asterisks denote a significant (p < 0.05) change. All values are mean ± S.E.M.