Intrasegmental Proprioceptive Influences on the Period of the Swimmeret Rhythm in Crayfish

When the swimmerets of decapods beat, they do so because the muscles of each swimmeret are driven by a series of periodic bursts of impulses in its motor neurones. We investigated the effects of proprioceptive feedback on the period of this motor pattern by interfering with the movement of particular swimmerets. In different experiments, we observed three different kinds of results during interference with a swimmeret. Either the period decreased, or it did not change, or bursting was inhibited altogether. These different results are discussed in terms of the connectivity of different command fibres.