Sensory-induced plasticity of motor pattern selection in the lobster stomatogastric nervous system

In a previous study, a bilateral sensory input pathway to the crustacean stomatogastric nervous system was reported to induce the functional switching of an identified motor neuron (VD) from one rhythm generating neural network (the pyloric circuit) to another (the cardiac sac network). In the present in vitro study on the spiny lobster, Palinurus vulgaris, we have shown that under certain conditions, repetitive trains of phasic stimulation (1 s, 40 Hz) of one of these sensory nerves elicits either an increase or a decrease in efficacy of the VD switching response. In preparations showing no previous sign either of increase or decrease in VD switching, either response can be induced by prior conditioning stimulation. The increasing effect can be induced by unpaired conditioning stimulation of the contralateral sensory nerve. Conversely, the decrease in switching efficacy is obtained by pairing stimulation of the sensory-motor pathway with that applied to its contralateral partner. Both the experimentally induced increase and decrease in VD switching are long-lasting, remaining observable for at least 20 min and in some cases up to 3 h after the original conditioning procedure. Our results suggest that this system provides a suitable 'simple' model for the analysis of experience-related plasticity of the switching of a neuron from one network to another.