The effect of modulatory neuronal input on gastric mill frequency

We study the crustacean stomatogastric nervous system to gain insight in the interaction of oscillators of different intrinsic frequencies. We show how fast inhibition from the pyloric network interacts with a slow modulatory input to control the frequency of the gastric mill rhythm. We deduce that the timing of the pyloric input is crucial in determining what effect it will have on the frequency of the gastric network. Over one set of timings, the modulatory input and the pyloric input work together to determine the frequency and over another set of timings, the effect of the pyloric input is mitigated by the modulatory input.