Journal of Comparative Physiology A

, Volume 203, Issue 10, pp 831–841 | Cite as

Characterization of the encoding properties of intraspinal mechanosensory neurons in the lamprey

  • Nicole Massarelli
  • Allan L. Yau
  • Kathleen A. Hoffman
  • Tim Kiemel
  • Eric D. TytellEmail author
Original Paper


Proprioceptive sensory inputs are an integral part of the closed-loop system of locomotion. In the lamprey, a model organism for vertebrate locomotion, such sensory inputs come from intraspinal mechanosensory cells called “edge cells”. These edge cells synapse directly onto interneurons in the spinal central pattern generator (CPG) circuit and allow the CPG to adjust the motor output according to how the body is bending. However, the encoding properties of the edge cells have never been fully characterized. To identify these properties and better understand edge cells’ role in locomotion, we isolated spinal cords of silver lampreys (Ichthyomyzon unicuspis) and recorded extracellularly from the lateral tracts where edge cell axons are located. We identified cells that responded to mechanical stimuli and used standard spike sorting algorithms to identify separate units, then examined how the cells respond to bending rate and bending angle. Although some cells respond to the bending angle, as was previously known, the strongest and most common responses were to bending velocity. These encoding properties will help us better understand how lampreys and other basal vertebrates adapt their locomotor rhythms to different water flow patterns, perturbations, or other unexpected changes in their environments.


Mechanosensory Encoding Lamprey Proprioception Locomotion 



Analysis of variance


Central pattern generator


Kolmogorov–Smirnov test for identical distributions


Principal component analysis





Bending directions


Center to left


Left to center


Hold on left side


Center to right


Right to center


Hold on right side



This study benefited from discussions with Avis H. Cohen, Lisa J. Fauci, Christina Hamlet, and Megan C. Leftwich. Funding support was received from the National Science Foundation under Grant DBI-RCN 1325165 (to L. J. Fauci and A. H. Cohen). This material is based upon work supported by, or in part by, the US Army Research Laboratory and the US Army Research Office under Contract/Grant No. W911NF-14-1-0268. All applicable international, national, and institutional guidelines for the care and use of animals were followed. All procedures performed in studies involving animals were in accordance with the ethical standards of the Tufts University animal care and use committee.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.


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Copyright information

© Springer-Verlag GmbH Germany 2017

Authors and Affiliations

  1. 1.University of Maryland Baltimore CountyBaltimoreUSA
  2. 2.Tufts UniversityMedfordUSA
  3. 3.University of MarylandCollege ParkUSA

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