Computational modeling of the effects of mechanosensory feedback on the locomotion of lampreys with spinal injuries*

Lampreys are basal fish that serve as model systems for locomotion and neurophysiology studies. While spinal cord injuries in mammals often result in a permanent loss of function, other vertebrates, such as lampreys, can partially or wholly recover locomotor functions such as swimming. The exact mechanism by which recovery occurs is not well understood. One hypothesis is that swimming in lampreys may recover through amplified proprioceptive (body-sensing) feedback. We employ a multiscale, integrative, computational neuromechanical model of an anguilliform (eel-like) swimmer fully coupled to a viscous, incompressible fluid in an immersed boundary framework to study the relations between neural signaling and swimming. This model, driven by coupled phase oscillators, can receive sensory feedback from changes in the body. We use this model to perform computational experiments which examine the effects of mechanosensory feedback on swimming performance. Our results show that feedback amplification below a spinal lesion is sometimes sufficient to partially or entirely restore normal swimming behavior.