Non-undulatory locomotion in the lamprey

The lamprey (a lower vertebrate, cyclostome), in addition to ordinary swimm ing, is also capable of crawling. Here we describe crawling forward in a na rrow U-shaped tunnel. A rapid movement along the tunnel was evoked by stimu lating the tail. The muscle activity responsible for propulsion was confine d to the area around the body bend. Muscles on the inner (concave) side wer e activated when approaching the turn, and inactivated on the top of the ar e. Muscles on the outer (convex) side were co-active with their antagonists . but also active in the area of straightening of the body bend. This patte rn of muscle activity propagated along the body. The role of central and re flex mechanisms in the generation of locomotor movements is discussed. Neur oReport 12:1803-1807 (C) 2001 Lippincott Williams & Wilkins.