Perturbation of the activity of a single identified neuron affects long-term memory formation in a molluscan semi-intact preparation

The aim of this study was to investigate the neural basis of operant conditioning in a semi-intact preparation of the pond snail, Lymnaea stagnalis. Lymnaea learns, via operant conditioning, to reduce its aerial respiratory behaviour in response to an aversive tactile stimulus to its open pneumostome. Here we report the successful conditioning of naive semi-intact preparations to show 'learning in the dish' and long-term memory that persists for at least 18 h. The neurons that generate this behaviour are readily identifiable and, for the first time, we have recorded from a neuron during a training paradigm that leads to long-term memory formation in the same preparation. Specifically, we recorded from the respiratory neuron Right Pedal Dorsal 1 (RPeD1), which is part of the respiratory central pattern generator and initiates the aerial respiratory behaviour. Previous studies have shown that long-term memory of this behaviour results in reduced RPeD1 activity. In the present study, we demonstrate that preventing RPeD1 impulse activity between training sessions reduces the number of sessions needed to produce long-term memory in our semi-intact preparation.