After a brief lunch break, we went on to the next session. Lisa Bogusch from our department in Berlin started out by telling us how sleep is required for proper long-range navigation of honeybees. She uses RFID technology to track the movements of individual bees in the hive.
Next up was my PhD thesis advisor and mentor Martin Heisenberg. His talk was on the fly version of learned helplessness: learned uncontrollability. These experiments were performed in the so-called heat-box: a fly walks back and forth in a dark box, the ceiling and floor of which can be heated, heating the entire chamber almost instantaneously. Whenever the fly walks into the 'punished' half of the chamber, the temperature increases until the fly leaves the half again. When flies are subjected to uncontrollable heat before the experiment, learning performance declines significantly, reminiscent of learned helplessness. Only females show this decrease and if you feed antidepressants to the females, they don't show the decrease. Puzzelingly, Troy Zars in Missouri showed that a superficially very similar treatment enhances performance rather than reducing it. The reason for this difference is still not clear.
The third speaker of the session was Martin Schwärzel. He showed us a very nice series of experiments in which he analyzed the necessity and sufficiency of the dunce phosphodiesterase influencing cAMP levels in the fly brain. By switching the dunce gene off in certain brain areas and leaving it intact in all others or by switching it on only in certain areas and keeping it switched off in all others, he found that dunce expression in the antennal lobes and the mushroom-bodies is sufficient to restore learning in a dunce mutant background. Dunce expression is necessary in either of the two structures. On the level of the antennal lobes, dunce is required in GABAergic local interneurons.
Melanie Hähnel was the final speaker of this session. She recently finished her PhD in our department in Berlin and is now in Frankfurt working on bees. Her project there is to inject caged oligonucleotides to candidate genes into the bee brain and then use laser light to uncage the compounds such that they can down-regulate their target genes in specific brain areas at specific times.