[Electrophysiologic study of the serotoninergic neuron C1 in the pteropod mollusk Clione]

Functional characteristics of the cerebral serotoninergic neuron (C1) have been studied in the pteropod mollusc Clione limacina. The C1 neuron axon projected to the buccal ganglia and axon collaterals terminated in buccal nerves. Stimulation of the C1 neuron activated the feeding rhythm generator in the buccal ganglia. Effects developed relatively slowly and far outlasted the period of C1 neuron stimulation. The C1 neuron received synaptic feedback from buccal neurons. As a result, the C1 neuron activity was cyclically modulated with respect to feeding rhythm generation. There was a correlation between the activity of the C1 neurons and that of the locomotor generator located in the pedal ganglia. Activation of the locomotor generator, both spontaneous and evoked by stimulation of some command neurons, was accompanied by excitation of the C1 neurons. The correlation between the activities of the locomotor generator and of the C1 neurons is suggested to be one of manifestations of the feeding synergy including simultaneous activation of the locomotor and buccal systems.