Fig. 11. Red pigment concentrating hormone (RPCH) is able to affect the pyloric pattern, shown by the fact that it did so in two of nine preparations with the stn blocked, one of which is shown here. Recordings of the pyloric pattern in (A) control saline, (B) during RPCH (10^–6 mol l^–1) bath application and (C) when washed with control saline. Note that, in contrast to the vast majority of preparations, the pyloric pattern continued even when the stn was blocked in this preparation. To ensure that this was not due to an incomplete block of condition in the stn, the stn was later cut, which did not alter the pattern of activity recorded. RPCH strongly activated the complete core pyloric pattern [bursting in the PD, LP, PY neurons seen on the lvn and the dlvn (PD), as well as weak bursting in the IC neuron]. Nerves: mvn, medial ventricular nerve (recording action potentials of the VD and IC neurons); dlvn, dorso-lateral ventricular nerve (recording action potentials of the PD neurons); lvn, lateral ventricular nerve (recording action potentials of the PD, LP and PY neurons).