Synaptic contribution to the production of the plateau formation of the biopotential of somatic neuromembranes treated with convulsants: experiment on the identified giant neurone of a snail's subesophageal ganglion-complex

I) On an identified giant neurone of the right parietal ganglion in a snail's subesophageal ganglion-complex, the synaptic contribution to the production of the plateau formation of biopotential or grouped spike discharges of the soma has been studied in the presence of a convulsant. 2) The orthodromic stimulation of a peripheral nerve (the intestinal nerve) can elicit the plateau formation of biopotential, instead of normal spike discharges, in the identified neurone treated with a convulsant. 3) With the application of a convulsant, for example bemegride which was in a concentration less than that necessary to produce the plateau formation, an EPSP accompanied a spike with a constant delay. This EPSP is a product of a proprioceptive reflex arc consisting of two excitatory synapses with a certain subordinate neurone. 4) Later, in the presence of a convulsant, spontaneously conveyed multiple EPSP's were observed on the biopotential of the identified neurone. These multiple EPSP's produced grouped spike discharges or the plateau formation of biopotential of the neurone. 5) The multiple EPSP's may be produced by the grouped spike discharges of the subordinate neurone, the membrane property of which would be changed by a convulsant. It is presumed that the grouped spike discharges or the plateau formation of biopotential often occurs synchron. ously in many neighboring neurones by means of synaptic triggering in the presence of a convulsant.