“…The sea lamprey ( Petromyzon marinus L.) offers a unique vertebrate model for studying axonal regeneration due to its remarkable ability to spontaneously recover from a complete SCI (see [2] , [3] , [4] ). Axon regeneration research in lampreys has mainly relied on the study of individually identifiable giant descending neurons (e.g., [5] , [6] , [7] ). These giant descending neurons of lampreys are located in the brainstem and project their axons along the spinal cord.…”