How do bees learn what scents worth it to follow

Scientists at the Free University of Berlin and Bernstein Center Berlin may have traces of the scent memory in a specific region Locate the bee brain. How successful are bees in search of food depends largely on how well they detect nectar-rich flowers from a distance by their scent and distinguish it from less productive blossom. The researchers led by Prof. Dr. Randolf Menzel, a neurobiologist at the Department of Biology, Chemistry and Pharmacy, Free University, went to the question of whether and how the bee the relationship between fragrance and nectar of a flower to remember, and whether this association in the brain of the bee place. The work was supported by the Federal Ministry of Education and Research under the projects, "Bernstein Center Berlin" and "Bernstein Focus learning: memory and decision making" financed.

The researchers adapted this nectar foragers from the swarming out of their floor, roped them and left them in her lab as it were back to school: The curriculum had five different artificial fragrances. After everyone had been introduced to five, was in a learning phase, a fragrance rewarded after each presentation with a drop of sugar solution, while another went unrewarded. This type of classical Pavlovian conditioning is based on the so-called proboscis-extension reflex that is triggered when the antennae of insects come into contact with sweet liquids. The bees quickly learned to stretch the rewarded scent their proboscis to lick the sugar solution, and showed this response even three hours after the learning phase.

To investigate the neural basis of this memory process, the biologist Martin Strube-Bloss measured as part of his dissertation at the Free University of Berlin, now at the Max Planck Institute for Chemical Ecology in Jena, the electrical reactions of certain nerve cells, namely the output neurons in the mushroom bodies of the brains of bees that were already listed as candidates for learning processes in space. The results surprised the researchers: During the learning phase, the activities changed in the neurons not examined. But three hours met after the learning phase, a change: more neurons responded to the stimulus associated with reward, and the answers to these were made stronger. The researchers therefore had actually find a memory trace. Because of the delay they could even suggest that this had nothing to do with the learning process itself or with the short-term memory, but that they had apparently identified the location of the long-term odor memory.

A mathematical analysis of the neuro-computer scientist Martin Nawrot from the Free University of Berlin, showed that the memory trace in the mushroom body is very reliable. Already 150 milliseconds after presentation of an odor could say the researchers because of the nerve cell activity, whether it was the scent of sugar heritage was worth or not. The bees could therefore confidently rely on their output neurons of the mushroom body to decide what scent is promising, or - in the wild - It is a nectar-bearing flowers and worth pursuing.

On the basis of their results, the researchers now create a computer model of the bee brain, the virtual associate odors with a reward and make decisions based on the knowledge acquired can be. Such artificial brains will be inspired in the near future, robots are used by living things.

The Bernstein Center Berlin is part of the national Bernstein Network for Computational Neuroscience (NNCN). The BMBF NNCN was founded with the aim of pooling the capacities in the new research discipline of Computational Neuroscience, to network and develop. The network is named after the German physiologist Julius Bernstein (1835-1917).

Publication:
Strube-Bloss MF *, Nawrot MP *, Menzel R (2011): Mushroom Body Neurons Encode Output Odor-Reward Associations J. Neurosci. 31: 3129-3140, * equal contribution

Source: Free University of Berlin