Multiple effects of an identified proprioceptor upon gastric pattern generation in spiny lobsters

1. Using deafferented preparations of the stomatogastric nervous system of spiny lobsters (Panulirus interruptus), we stimulated the central soma of the Anterior Gastric Receptor neuron (AGR) and analyzed sensorimotor integration in the gastric central pattern generator during rhythm production. 2. Driving AGR to spike tonically at lower frequencies (10-20/s) accelerated the gastric rhythm, while higher frequencies (> or = 30/s) suppressed it. 3. Shorter spike trains in AGR evoked phase-dependent resetting of the gastric rhythm. Repetitive trains could entrain rhythms to both longer and shorter cycle periods. Some pattern-generating effects are consistent with effects upon the lateral gastric neuron, an influential member of the gastric mill network. 4. AGR affected the burst intensity of many of the gastric neurons in specific, complex ways. Some power-stroke motor neurons were excited because AGR activated excitatory, premotor interneurons (E cells). However, AGR also activated parallel, seemingly inhibitory inputs, whose mechanism remains unclear. Still other effects on motor neurons may be mediated partly by synaptic interactions within the network.