How do honey bees learn to ignore irrelevant stimuli?

VILLARREAL, F.; LOCATELLI F; SMITH B

Tempe, Arizona , EEUU

Workshop; UBEP ASU 2008; 2008

School of Life Sciences, Arizona State University, USA

Learning to ignore irrelevant stimuli Francis Villarreal Social Insects Research Group, School of Life Sciences. ASU Animals live in a complex world in which relevant information with predictive value is presented in a soup of meaningless accompanying stimuli. In this context animals must be able to detect and identify the relevant cues and filter out the irrelevant ones to take adaptive decisions. To solve this task becomes even more difficult when the meaning or irrelevance is not fixed, but instead depends on experience. The present project deals with how experience shapes the tuning of the sensory systems and the brain to perceive components in complex stimuli. We use the honey bee and its incredible olfactory skills as experimental model. Forager bees continuously learn the contingency between odors and rewards, but equally important, they also learn to ignore stimuli that have no predictive value. This last form of learning, called “conditioned stimulus pre-exposure effect” is induced by repeated unrewarded exposure to an odor. Previous calcium imaging experiments studying representation of odors and odor-mixtures in the antennal lobe revealed that unrewarded exposure to one odor reduces the neural representation of that odor when it is later present in a mixture. These results constitute a neural correlation of ignoring an irrelevant component in an odor mixture. However, experiments that reveal this phenomenon at the behavioral level have not jet been addressed. In the present project we are performing a series of experiments based on behavioral assays aimed at evidencing and characterizing this phenomenon under laboratory conditions. Restrained honeybees are exposed to unrewarded presentation of an odor and afterwards they are subjected to appetitive conditioning using an odor mixture that contains the odor used during the pre-exposure phase. After the animals have learned the predictive value of complex stimuli, animals are tested with the pure components to reveal the relative contribution of them to the perception of the mixture. Preliminary results show that the learning of the pre-exposed odor is reduced in comparison to learning in control animals that were not pre-exposed. On the other hand learning of the novel odor is increased in comparison to non pre-exposed animals. Results also indicate that the mentioned effect is not equally induced by all odors