THE PYLORIC PATTERN OF THE LOBSTER (PANULIRUS-INTERRUPTUS) STOMATOGASTRIC GANGLION COMPRISES 2 PHASE-MAINTAINING SUBSETS

The pyloric pattern approximately maintains phase over a three- to fiv efold frequency range when the pattern is defined by the pacemaker bur st beginning. However, in this reference frame certain pattern element s maintain phase better than others, which suggests phase-maintaining subgroups might exist. Reanalysis of these data in reference frames de fined by each element shows the pattern contains two groups of pattern elements within which phase is well maintained but between which main tenance is relatively poor. A third element shows intermediate mainten ance with each group. If ventricular dilator neuron burst beginning (V DB) is chosen as pattern beginning, all members of one group occur ear ly in the pattern, all members of the other occur late in the pattern, and the intermediate element occurs between the groups. Thus, at leas t for phase maintenance, VDB is a ''natural'' pyloric pattern beginnin g. These results suggest full description of complex patterns is best achieved by analysis in many reference frames.