Meeting Abstract

P1-96   -   Acute behavioral responses to partial spinal cord transections in the larval sea lamprey Gonzalez-Kosasky, DJ*; Katz, HR; Tytell, E; Morgan, JR; Amherst College, Amherst, MA; Marine Biological Laboratory, Woods Hole, MA; Tufts University, Medford, MA; Marine Biological Laboratory, Woods Hole, MA hkatz@mbl.edu

Many species of non-mammalian vertebrates are capable of substantial neural regeneration and functional recovery after traumatic spinal cord injury. The sea lamprey (Petromyzon marinus) recovers swimming and burrowing behaviors after a complete spinal cord transection by 10-12 weeks post injury, due to robust neural regeneration. While the long-term neuroplasticity that supports functional recovery during spinal cord regeneration has been studied extensively, much less is known about the acute neuroplasticity that allow animals to retain some functionality after partial spinal cord injuries. We set out to determine how partial spinal cord lesions acutely impact locomotion. We asked how lesions in reticulospinal tracts impact swimming and whether swimming behavior changes over 3 days post injury, which could suggest acute neuroplasticity. We focused on two specific lesion types: medial and bilateral lesions. We performed video imaging (60 fps) and kinematic analysis of late larval sea lampreys before their respective injuries (control), as well as 2 and 72 hours post-injury, followed by confirmation of the spinal lesion site using histology. The most dramatic deficits were observed after bilateral lesions; these animals had lower amplitude undulations, difficulty starting and stopping locomotion, and overall decreased swimming activity. After 3 days post-injury we observed no improvement in swimming behavior. Instead, swimming worsened over time, which may be due to post-injury retraction of the injured axons. Animals that underwent medial spinal lesions were less impaired, but often fatigued more quickly than before injury. These preliminary findings suggest that the lateral tracts of the spinal cord are essential for initiating locomotion, while the medial tracts are less critical, and that the acute behavioral responses post-injury are dynamic.