[Neurons responsible for non-synaptic coordination of motor rhythms in CNS of Lymnaea].

Giant hyperpolarizing waves in the nitrergic neurons B2 controlling gut motility in Lymnaea are characteristic elements of transient coordination between the B2 rhythm and that of the buccal central pattern generator. Here, we identified a novel group of neurons that seems to be responsible for the occurrence of giant hyperpolarizing waves in the B2 neurons. Each of the paired buccal ganglia was found to contain two such neurons. Electrical stimulation of these neurons produces non-synaptic direct deep and long lasting wave of hyperpolarisation in the neuron B2. Besides, these neurons are capable of increasing the frequency of the buccal rhythm and affecting the activity ofmotoneuron B4 involved in the buccal rhythm. Their effects are potentiated by nitric oxide. The results suggest that the identified neurons might coordinate feeding motor rhythms via the mechanism of volume transmission.