Distributed Plasticity for Olfactory Learning and Memory in the Honey Bee Brain

Abstract

Honey bees have a number of sophisticated learning abilities to track rapidly changing distributions of nectar and pollen resources the colony needs for survival. The honey bee is an excellent animal in which to study learning because these abilities can be evaluated both in the field and under laboratory conditions that permit use of physiological analyses. Our focus is on how the neural bases for these learning abilities can be tracked into different levels of processing in the CNS (central nervous system). We specifically review two kinds of conditioning protocols to show first how behavior changes over conditioning and second how plasticity can be tracked into the antennal lobe (AL) as well as in the mushroom body (MB). We begin by pointing out that, particularly when the learning problem becomes difficult, the behavioral response to conditioned stimuli proceeds in a nonlinear manner. Honey bees may have difficulty in making an appropriate response until some point when a precipitous change in their behavior occurs. We then discuss how plasticity related to behavioral conditioning has been reported at subsequent processing levels in the AL as well as in the MB, which receives input from the AL. We point out that this distributed plasticity in the CNS for any kind of learning raises an important conceptual issue, which regards how changes at a higher level of processing (the MB) can be adapted to track and perhaps be augmented by changes at an earlier level (the AL). We show by example how coupled behavioral and physiological analyses combined with computation modeling can begin to address these important issues.