Dynamics in intracellular signaling underlie modulatory processes in neurons. We are examining the role of co-transmitters in modulating a bursting neuron that is part of a multifunctional pattern generator. The stomatogastric nervous system (STNS) of crustaceans is the rhythmic pattern generating network underlying swallowing, chewing, and filtering of food. Distinct but overlapping circuits compose the pattern generating circuits of the STNS, and the gastric mill circuitry is responsible for chewing behavior. The lateral gastric neuron (LG) is an identified neuron that is part of a reciprocally inhibitory pair of neurons pivotal to gastric mill pattern generation (Coleman et al., Nature 1995). We have demonstrated that a plateau potential supports LG bursting as elicited by an identified projection neuron (modulatory commissural neuron 1, MCN1) (see Brown and Wood, SFN Abstr, 2003). Crab tachykinin related peptide Ia (CabTRPIa), one of the three identified co-transmitters in MCN1 that include proctolin a...