Separate neural pathways respond to different noxious stimuli affecting respiratory pump frequency in Aplysia fasciata

Miriam Levy, Abraham J. Susswein

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    6 Scopus citations


    Neural circuits responsible for both conditioned and unconditioned respiratory pumping to three stimuli modulating respiratory pumping were examined. The stimuli used were: (i) reduction of pH; (ii) increase and (iii) decrease in seawater concentration. Ablation of the osphradium, but not of the rhinophores, abolished responses to all 3 stimuli. Cutting the pleural-abdominal connectives led to a decrease in responses to lowered pH, but did not affect responses to changes in seawater concentration. Further lesions showed that integrity of the cerebral-pleural ganglion is needed for animals to respond to a decrease in pH. Thus, neural circuitry entirely within the abdominal ganglion and the periphery innervated by the ganglion is sufficient for mediating responses to changes in seawater concentration, while the cerebral ganglion is needed to respond to lowered pH. Different transmitter mechanisms are also used by pathways responding to changes in seawater concentration and to decreased pH: 5,7-dihydroxytryptamine in concentrations which cause depletion of serotonin blocked the response to lowasd pH, but not to altered seawater concentrations.

    Original languageEnglish
    Pages (from-to)218-229
    Number of pages12
    JournalBrain Research
    Issue number1-2
    StatePublished - 9 Jul 1993

    Bibliographical note

    Funding Information:
    Acknowledgements. We thank Sylvia Markovich for help in performing some of the experiments, Itay Hurwitz for helpful discussions, and Ron Goldstein, Miriam Schwarz and Aron Weller for comments on an earlier draft of the manuscript. We also thank John Byrne for comments on a (much) earlier manuscript, and for help with experiments that are not included in this paper, but which were instrumental in suggesting ideas that eventually led to the work described. Without his help, this paper would not have been written. This work was supported by Grant 475/90 from the Basic Research Foundation of the Israel Academy of Sciences and Humanities.


    • Aplysia
    • Defense
    • Learning
    • Respiratory pumping
    • Salinity
    • Serotonin
    • pH


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