Metamorphosis-related changes in the lateral line system of lampreys, Petromyzon marinus

J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2008 Nov;194(11):945-56. doi: 10.1007/s00359-008-0367-6. Epub 2008 Sep 16.

Abstract

Lamprey metamorphosis leads to considerable changes in morphology and behavior. We have recently reported that larval lampreys possess a functional lateral line system. Here we investigated metamorphic morphological changes in the lateral line system using light and electron microscopy. Functional modifications were studied by recording the trunk lateral line nerve activity of larvae and adults while stimulating neuromasts with approximately sinusoidal water motion. We found a general re-patterning of neuromasts on the head and trunk including an increase in numbers, redistribution within the pit lines, and shifts of the pit lines relative to external features. The trunk lateral line nerve response was qualitatively similar in adults and larvae. Both showed two neuronal populations responding to opposite directions of water flow. Magnitude of the response increased monotonically with stimulus amplitude. At low frequencies, the response lag relative to the stimulus maximum was approximately 220 degrees , and the gain depended approximately linearly on frequency, confirming that superficial neuromasts are velocity detectors. Changes in phase lag with increasing stimulus frequency were steeper in larvae, suggesting slower afferent conductance. The response gain with frequency was smaller for adults, suggesting a narrower frequency discrimination range and decreased sensitivity. These changes may be adaptations for the active lifestyle of adult lampreys.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Action Potentials / physiology
  • Analysis of Variance
  • Animals
  • Lampreys / anatomy & histology*
  • Lampreys / growth & development*
  • Larva
  • Lateral Line System / growth & development*
  • Lateral Line System / ultrastructure
  • Metamorphosis, Biological / physiology*
  • Microscopy, Electron, Transmission / methods
  • Nerve Fibers / physiology
  • Nerve Fibers / radiation effects
  • Physical Stimulation