Periodic and oscillatory firing patterns in identified nerve cells of Lymnaea stagnalis L.

: Firing patterns in identified neurons of Lymnaea stagnalis L. were analyzed by various mathematical methods including spike density function (SDF), interspike-interval histograms (ISI), Fourier transform and correlation analysis. Input-3 (IP3) events observed in most of the neurons of the respiratory regulatory system caused prominent changes in the firing frequency of the cells. Similarly, quasiperiodic firing patterns were observed in the neurons of buccal ganglia controlling feeding behavior. Apart from the known periodic patterns a fine oscillation of firing rate was observed in a large number of neurons in the visceral and parietal ganglia. The frequency of this oscillation varied between 0.2 and 0.4 Hz. The most obvious oscillatory patterns were found in the A-cells presumably resulted by periodically appearing synaptic excitation. Moderate intracellular hyperpolarizing current injection, low-Ca/high-Mg saline and application of d-tubocurarine failed to abolish the slow oscillations. Application of Ca-channel blocker cadmium, however, completely eliminated the oscillation in a reversible manner.