Regeneration of locomotor command systems in the sea lamprey.

Ammocoete larvae of the sea lamprey were allowed to recover from a complete transection of the spinal cord posterior to the last gill arch. Specimens were then prepared for focal extracellular stimulation of the brainstem in the region known to contain the command systems for swimming. In 4 preparations where behavioral recovery had occurred, stimulation in this region would initiate swimming, indicating that the command function of this 'locomotor' region had recovered.