[The effect of the delta sleep peptide and serotonin on the neurons of the snail].

The present paper describes the results concerning the influence of delta sleep-inducing peptide (DSIP) and serotonin (5-HT) on electrophysiological properties of the identified snail neurons. The experiments were performed on semi-intact preparations from Helix lucorum L. DSIP inhibited spontaneously active neurons and reduced responses of silent cells to depolarizing currents and tactile stimuli.

[The effect of a magnesium-free solution on the parameters of the spontaneous excitatory postsynaptic potentials in identified snail neurons].

This investigation has revealed that application of magnesium-free medium to snail brain preparation changes the parameters of excitatory input to the identified neurons of the snail: the distribution of amplitude and intervals between EPSP. The other parameters (time to peak level and duration of EPSP) remained unaltered. It is concluded that spontaneous firing activity of initially silent neurons in magnesium-free solution develops as a result of increased efficiency of excitatory input.

[The effect of a magnesium-free solution on neuronal activity in the snail].

This investigation has revealed that application of magnesium-free medium to snail brain preparations results in the development of paroxysmal depolarization shifts (PDSs) and depolarizing afterpotentials in some neurons. The neurons studied were classified by their responses to low extracellular magnesium as active or passive. In the active neurons, typical PDSs observed were characterized by plateau potential with complete inactivation of the spike generating mechanism.