Randolf Menzel, professor emeritus of our institute in Berlin started the last session of this fantastic little meeting with an enthusiastic presentation on naviating bees which he followed by harmonic RADAR. His team first trained bees to fly to a certain feeder. Then they removed the feeder and trained a separate group of bees to another feeder, at an angle of either 30° or 60° to the old feeder, as seen from the hive. The second group of bees would then dance to recruite the first group of bees to the new feeder. This first group of bees then had a choice of either flying towards the newly indicated feeder which they had never visited, or towards the remembered one from two days before. It turned out that most bees followed the indicated direction, but some bees also headed at an intermediate angle between the two feeders or turned towards the old feeder after they had arrived at the new feeder. Interestingly, this only happened for the group where the angle between the two feders was 30° and not with the bees where the feeders were separated by 60°.
The second speaker of the final session was Thomas Préat telling us about two-photon imaging of protein kinase A (PKA) activity in intact flies. He found that bath-application of dopamine acivates PKA only in the vertical lobes but not in the medial lobes of the mushroom-bodies. In contrast, octopamine activates PKA in all MB lobes. Interestingly, the dopamine receptors are not localized to the vertical lobes. Imaging dunce mutants in this setup, he showed that PKA is activated in all MB lobes in this mutant after dopamine application. Suggesting that the rutabaga adenylyl cyclase is the coincidence detector of CS and US in the mushroom-bodies, these mutants do not show the synergistic enhancement of PKA activation after pairing of acetylcholin with octopamine or dopamine.
The penultimate speaker of our symposium was Ron Jortner telling us about a different model system, the locust. He studies the olfactory system of this insect and presented data about the peculiar synchrony that projection neurons exhibit, which is mediated by the action of inhibitory local interneurons in the antennal lobe. He also showed us that projection neurons make excitatory synaptic connections to local neurons (which in turn make direct inhibitory connections onto the projection neurons). In this system, the projection neurons don't seem to make direct connections with each other. This leads to a star-shaped network where the lcal neurons receive ecitatory input from the projection neurons which leads to inhibition of the projection neurons. This neuronal organization leads to synchronous oscillations in the projection neuron populations acivated by the odor.
The very last speaker of the symposium was Yi-Chun Chen who talked about the role of odor quality in olfactory conditioning of Drosophila larvae. Her project was to assemble a generalization matrix for five different odors using a number of different testing procedures. Reassuringly, the different procedures generated very similar data, allowing for a pooling of the data in a singular larval odor generalization matrix.

This talk concluded a fast-paced, data-packed symposium of 35 different talks. we had an exciting time and I'm looking forward to a future meeting of this great bunch of people in the next couple of years.