AMPHIBIAN MAUTHNER CELLS

Presently available data on anatomical, electrophysiological, and behavioral aspects of the Mauthner cell in amphibians are reviewed. Urodelian Mauthner cells appear morphologically distinct from those in anurans with respect to their abundant somatic dendrites, axon cap structures, lack of nodes of Ranvier, and size of axon collaterals. The presence of Mauthner cells does not seem to correlate with the presence of a tail or with an aquatic life-style in either larvae or adults, as they are also found in terrestrial adults, as well as in species without an aquatic larval stage. Electrophysiological data on Mauthner cell circuits are available for only two anuran species and indicate some interspecific differences. Special attention is given to a comparison of startle responses in larval and adult anurans and their possible relationship to Mauthner cell activities. Because of specific differences in Mauthner cell activities, as well as in startle response performance, it is argued that amongst the various ichthyopsid species Mauthner cells may have been adapted to modified functions due to the diverse morphoecological situations in which they are found.