№ 343/2015 from Nov 03, 2015
Biologists at Freie Universität Berlin in the group of the highly regarded bee researcher Prof. Dr. Randolf Menzel have demonstrated for the first time the importance of deep sleep for learning processes in the brains of insects. The experiments by the Berlin scientists suggest that the link between sleep and memory formation is evolutionarily far older than previously thought. For mammals this relationship has been known for some time. "We were able to prove that sleep is critical to memory consolidation even in insects," says Ruth Bartels who, along with her colleague Hanna Zwaka, published the research findings in a recent issue of the prestigious scientific journal Current Biology.
Honeybees sleep several times during the day and at night. Up to now scientists were unsure of the reasons. Now it is clear that bees also use their sleep to improve their memories. In this experiment, the scientists conditioned the bees to a heat stimulus. During learning the bees were exposed to a fragrance that they linked to the learning experience. One group of bees was exposed to the same fragrance several times during deep sleep. This had a significant effect on memory: About 70 percent of the bees showed the learned behavior the next day when they were given a heat pulse. In the control group, only half of the insects exhibited this behavior.
"From experiments with mammals and humans, we know that such a trigger during deep sleep leads to brain activity," says Hanna Zwaka. "It appears that the brain of bees also repeats – triggered by the stimulus – what the animal learned and in this way enshrines what was learned in memory." By contrast, the Berlin biologists also demonstrated in experiments that this mechanism does not work in awake animals.
Hanna Zwaka, Institute of Biology, Neurobiology and Behavior, Freie Universität Berlin, Email: firstname.lastname@example.org