The Relationship of Interlimb Phase to Oscillator Activity Gradients in Crayfish

The movements of anteriad appendages lag homologous movements of more posteriad appendages during crayfish swimmeret beating. The present experiments show that the direction of metachronal movement is maintained under conditions either (1) where the anteriad oscillator has a higher intrinsic frequency than the posteriad oscillator, or (2) where the anteriad oscillator has a lower intrinsic frequency than the posteriad oscillator. The magnitude of the interlimb phase is different in the two states. These results confirm earlier predictions of experiments on the control of anteriad oscillator excitability by a single burst of co-ordinating neurone input.