Fig. 1. Morphological and electrophysiological identification of the AGR. (A) Schematic drawing of isolated STNS with gastric muscles gm1 and gm4a,b. The bipolar cell body of the sensory neuron AGR is located immediately posterior to the cell bodies of the motor neurons in the STG and projects one axon via the dgn and agn to the gm1 muscles and one axon via the stn and sons to the CoGs. (B) Lucifer Yellow fill of AGR showing the location of the AGR soma in the STG. AGR possessed no arborization in the STG neuropil. (C) Two spike initiation zones contributed to AGR spontaneous spike activity. Top: multisweep recordings (n=56 sweeps) of agn, stn and son, triggered on the AGR action potential on agn. The AGR spike could be seen on all recordings. Bottom: 149 sweeps of agn, stn and son, triggered on the AGR action potential on stn. CoG, commissural ganglion; OG, oesophageal ganglion; STG, stomatogastric ganglion; AGR, anterior gastric receptor; agn, anterior gastric receptor nerve; aln, anterior lateral nerve; dgn, dorsal gastric nerve; dvn, dorsal ventricular nerve; ion, inferior oesophageal nerve; lgn, lateral gastric nerve; lvn, lateral ventricular nerve; mvn, median ventricular nerve; son, superior oesophageal nerve; stn, stomatogastric nerve.