Journal of comparative physiology

, Volume 128, Issue 3, pp 259–267 | Cite as

Properties of central motor neurons exciting locomotory cilia inTritonia diomedea

  • Gerald Audesirk


A pair of large, identifiable neurons (Pd 21), one in each pedal ganglion, can excite previously inactive locomotory cilia on the sole of the foot ofTritonia diomedea (Audesirk, 1978; Fig. 3). These neurons exert their effect via axons which innervate the foot and are probably central motor neurons for pedal cilia. IntactTritonia are stimulated to crawl by the application of 1.5 M NaCl to the tail, and conversely usually stop crawling when the chemosensitive oral veil is touched with food (sea whip,Virgularia sp.). The Pd 21 neurons are excited by 1.5 M NaCl applied externally to the tail, and are inhibited by sea whip touch to the oral veil (Figs. 4 and 5). When aTritonia performs its escape swim, the cilia move strongly, and the Pd 21 neurons fire bursts of spikes in phase with dorsal flexions (Figs. 6 and 7). After a swim, aTritonia rapidly crawls along the substrate; during this time the spiking rate of the Pd 21s is greatly accelerated. Interneurons thought to drive swim bursts produce monosynaptic EPSPs in the Pd 21s (Fig. 8). The Pd 21s are coordinated in their spike activity by synaptic activity which is synchronous in the two neurons regardless of the site of external stimulation, and by electrical coupling between the two cells via axons in a pedal commissure (Figs. 9 and 10). The coupling coefficient for passively conducted potentials is quite high, about 0.15, despite an axon 8 to 12 mm long separating the two cells.


Motor Neuron Coupling Coefficient Spike Activity Synaptic Activity Central Motor 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



biphasic postsynaptic potential


sea water


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Copyright information

© Springer-Verlag 1978

Authors and Affiliations

  • Gerald Audesirk
    • 1
  1. 1.Friday Harbor LaboratoriesUniversity of WashingtonFriday HarborUSA

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