Summary
Command fibers located in the circumesophageal connectives which modify scaphognathite and heart rhythms have been mapped and characterized in the crab,Cancer magister.
Behavior: Crabs show a variety of responses to external stimuli often including simultaneous cessation of cardiac and scaphognathite “pumping”. Habituation and a return to prestimulus rhythms results from continued stimulation. The response to short stimulus durations, on the other hand, generally outlasts the stimulus indicating the playing-out of a motor program.
Neurophysiology: Small bundles of fibers have been isolated from desheathed connectives. Activity in these fibers resulting from stimulation of various anterior sensory receptors was recordeden passant with suction electrodes. When sensory stimulation produced both electrical activity in the nerves under examination and a cardiac and/or scaphognathite response it was assumed such units were involved in inducing this response. This was tested by electrical stimulation delivered through the same electrode. Those units which produced similar responses to natural and artificial stimulation were deemed “command fibers”. It was invariably found that the minimum stimulating frequency needed to mimic naturally induced responses was much greater than the frequency at which the units discharged in response to those stimuli.
During mapping experiments, command fibers were characterized with respect to their positions in the connectives and by the responses they produced at different frequencies of stimulation. 68% of the fibers identified affected both cardiac and scaphognathite systems, 29% the scaphognathites alone and 3% the heart alone. The frequency-response profiles of single bivalent command fibers were often different from the heart and scaphognathites. These findings help explain the responses of both systems to natural stimuli and also indicate that the circulatory and respiratory systems not only perform in concert, but are often under common control.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Alexandrowicz, J. W.: The innervation of the heart of the crustacea. I. Decapoda. Quart. J. micr. Sci.75, 181–249 (1932)
Ashby, E. A., Larimer, J. L.: Modification of cardiac and respiratory rhythms in crayfish following carbohydrate chemoreception. J. cell. comp. Physiol.65, 373–380 (1965)
Atwood, H. L., Wiersma, C. A. G.: Command interneurons in the crayfish central nervous system. J. exp. Biol.46, 249–261 (1967)
Bullock, T. H., Horridge, G. A.: Structure and function in the nervous systems of invertebrates, vol. 2. San Francisco: W. H. Freeman & Co. 1965
Cooke, I. M.: Electrical activity and release of neurosecretory material in crab pericardial organs. Comp. Biochem. Physiol.13, 353–366 (1964)
Evoy, W., Kennedy, D.: The central nervous organization underlying control of antagonistic muscles in the crayfish. J. exp. Zool.165, 223–238 (1967)
Florey, E.: Studies on the nervous regulation of the heart beat in decapod crustacea. J. gen. Physiol.43, 1061–1081 (1960)
Kennedy, D.: Crayfish interneurons. Physiologist14, 5–30 (1971)
Larimer, J. L.: Sensory induced modifications of ventilation and heart rate in crayfish. Comp. Biochem. Physiol.12, 25–36 (1964)
Larimer, J. L., Kennedy, D.: The central nervous control of complex movements in the uropods of crayfish. J. exp. Biol.51, 135–150 (1969)
Larimer, J. L., Tindel, J. R.: Sensory modification of heart rate in crayfish. Anim. Behav.14, 239–245 (1966)
McMahon, B. R., Wilkens, J. L.: Simultaneous apnoea and bradycardia in the lobsterHomarus americanus. Canad. J. Zool.50, 165–170 (1972)
Mendelson, M.: Oscillator neurons in crustacean ganglia. Science171, 1170–1173 (1971)
Skobe, Z., Nunnemacher, R. F.: The fine structure of the circumesophageal nerve in several decapod crustaceans. J. comp. Neurol.139, 81–92 (1970)
Taylor, R. C.: Environmental factors which control the sensitivity of a single crayfish interneuron. Comp. Biochem. Physiol.33, 911–921 (1970)
Wiersma, C. A. G., Hughes, G. M.: On the functional anatomy of neuronal units in the abdominal cord of the crayfish,Procambarus clarkii Girard. J. comp. Neurol.116, 209–228 (1961)
Wiersma, C. A. G., Mill, P. J.: “Descending” neuronal units in the commissure of the crayfish central nervous system; and their integration of visual, tactile and proprioceptic stimuli. J. comp. Neurol.125, 67–94 (1965)
Wiersma, C. A. G., Novitski, E.: The mechanism of the nervous regulation of the crayfish heart. J. exp. Biol.19, 255–265 (1942)
Wilkens, J. L., McMahon, B. R.: Aspects of branchial irrigation in the lobsterHomarus americanus. I. Functional analysis of scaphognathite beat, water pressures and currents. J. exp. Biol.56, 469–479 (1972)
Author information
Authors and Affiliations
Additional information
This work was conducted at the Friday Harbor Laboratories of the University of Washington. We express our thanks to Dr. Robert Fernald for making facilities available. This work was supported by National Research Council grant numbers A5494 (JLW) and A5762 (BRM) and NIH postdoctoral fellowship NS 43039-02 (LAW).
Rights and permissions
About this article
Cite this article
Wilkens, J.L., Wilkens, L.A. & McMahon, B.R. Central control of cardiac and scaphognathite pacemakers in the crab,Cancer magister . J. Comp. Physiol. 90, 89–104 (1974). https://doi.org/10.1007/BF00698370
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00698370