Undulatory Locomotion — Simulations with Realistic Segmental Oscillator

Vertebrates like eel and lamprey move about by means of a undulatory locomotion. The neural mechanisms which underly this movement have been investigated in terms of circuitry, types of synaptic transmission, and general membrane properties. Intersegmental coordination is characterized by a phase lag (fixed proportion of cycle duration) between each consecutive spinal segment. In simulation of 20 segments, using realistic cell models, in which each segment mutually excites its’ closest neighbors, it is shown that a phase lag can be produced by increasing the excitability of only one segment. It will thus become the “leader” and consecutively entrain the remaining segments. This very simple neural organization can produce a flexible (forward and backward coordination), complex, and yet easily controlled motor behavior.