Figure 2

Influence of histamine on the odor-induced PN responses of the honeybee AL (protocol 2). A: False-color coded spatial activity patterns to the odor 2-octanol before, during and after histamine application. Only one histamine concentration was tested in this animal. The AL border is marked with a dotted line, antennal nerve is at the top. The positions of three identified glomeruli are indicated in each frame. The numbers at the top right in each image indicate the time elapsed from the latest treatment. B: Time traces of the three identified glomeruli, whose positions are marked in A. Odor application is shown by a black bar. Contrary to the compound signals, PN responses were temporally complex and were strongly sensitive to a histamine concentration of 10 mM. The responses reappeared in the wash and were even stronger. C: Odor-induced PN responses averaged over all animals (mean and SEM, n = 5) of the most responsive glomeruli. Asterisks give significant differences to the Ringer measurement (**P < 0.01, two-tailed paired t-test, performed on the original data). Histamine significantly reduced the odor-evoked signals.