A unique mushroom body extrinsic neuron, the PE1, and mechanisms of its role in associative learning and memory formation

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Learning leads to changes in neuronal networks. These changes should be traceable to the plasticity of single neurons. To understanding, how learned information and different memory stages influence the physiological properties of neural nets, it is advantageous to record repeatedly from the same identifiable neuron in different animals under changing experimental conditions. This is possible in the honeybee’s central nervous system. The unique pedunculus-extrinsic neuron number 1 (PE1) receives input inside the mushroom body, a higher-order integration center that is involved in sensory processing, associative learning and memory storage. In previous works PE1 showed associative plasticity to learned odors or after electrical stimulation of Kenyon cells (upstream neurons of PE1). We will use the PE1 to investigate systematically the 2cellular and network properties underlying associative plasticity during olfactory learning. We will record intra- and extracellularly from PE1, which can be identified due to its location and unique spiking behavior, while applying different conditioning paradigms. Neural correlates of learning and memory consolidation will be monitored on the molecular, cellular and network level. To this end we shall ask whether the changes observed in the course of learning and memory consolidation are an intrinsic property of PE1 and/or a property of upstream neurons. To answer this question, we will selectively stimulate the presynaptic neurons (Kenyon cells) and record intra- or extracellularly from PE1, while interfering pharmacologically and physiologically. These approaches will allow us to reveal the processes of memory formation at the single neuron and network level that potentially underlie associative learning and memory formation. Furthermore, we shall record extracellularly from PE1 to characterize systems related consolidation.