INTRODUCTION

The lamprey is an anguilliform swimmer: thrust is developed by the rostral-caudal passage of a wave of curvature over most of the body length. The patterns of muscle activity giving rise to this curvature are generated by pattern-generating circuitry within the spinal cord and continuously modified by sensory feedback (see Figure 1). Movement arises from the interactions of neural activity, the biochemical and physical properties of muscle, and the mechanical properties of both the body and the water. In this chapter we briefly discuss three aspects of this complex system. A brief review of work on pattern generation by the lamprey spinal cord will be followed by a presentation of a mechanical model of the lamprey body, and its interactions with muscle activation. Finally, the results of some initial studies of the hydrodynamics of anguilliform swimming will be given, along with an outline of future work to be carried out.

CENTRAL GENERATION OF THE LOCOMOTOR PATTERN

The pattern of muscle activation during swimming consists of alternating bursts of activity in the left and right ventral roots of each segment, with a rostral-caudal delay of activation along the length of the spinal cord (Figure 1).