Structural plasticity of synaptic circuits in the honeybee brain mushroom bodies associated with behavioral learning

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Investigation of cellular mechanisms underlying behavioral learning provides a growing body of evidence that acquisition of new behaviors induces synaptogenesis and restructuring of existing synapses. So far this question is mostly addressed to work carried out on the mammalian brain, while other highly organized animal groups exhibiting complex forms of behavior are not studied in this respect. The aim of the proposed work is to find out by means of quantitative electron microscopy (EM) whether experience-associated synaptogenesis occurs in the honeybee mushroom bodies (MBs), the higher brain centers involved in the formation of olfactory memory. More specifically, we shall focus on experience-related plasticity of inhibitory local synaptic circuits within the mushroom body input sites. This will be assessed by quantification of synapses on LM- and EM preparations stained for GABA ¿ neurotransmitters operating within the MB inhibitory circuits. The other question that we shall address is whether single or multiple learning trials are associated with structural plasticity in the MBs. Assuming that dynamic actin mediates possible restructuring of synapses or synaptic circuits, we will use the olfactory conditioning experimental paradigm to estimate filamentous actin dynamics within mushroom bodies during the learning process.