Propagation of electrical activity in the nerve cord and muscle syncytium of the nematodeAscaris lumbricoides

SummaryThe functional muscle syncytium overlying the nerve cord inAscaris lumbricoides is preferentially excited by anodal stimulation with an extracellular electrode. Cathodal stimulation preferentially excites the nerve cord, allowing determination of separate conduction velocities for the nerve cord and syncytium. The propagation velocity of the nerve cord is 16.2±1.2 cm/s; that of the syncytium varies with Ca2+ concentration, being 21.6±1.3 cm/s under normal conditions (Figs. 5, 6). Both values are too high to account for the propagation of contractile waves in the intact animal.Modulation of spontaneous electrical activity on a behaviorally significant time scale is observed. The modulation shows dorsal-ventral coordination if the right lateral line is intact, in accord with known nervous system asymmetry (Fig. 10).

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