Fig. 1.

(A) Photomicrograph of the stomatogastric ganglion. (Scale bar, 200 μm.) (B) Circuit map of the STG. The STG contains 12 cell types that innervate the pylorus and gastric mill of the crab stomach. These cells are individually identifiable, and their chemical (closed circles) and electrical (resistor symbols) synaptic connections are all known. We used 10 of these 12 STG cell types (not AB or Int1) for this study, as well as motor neurons of the cardiac ganglion as an outgroup for comparison. Example traces were taken from intracellular recordings of each of the 11 identified neuron types used in this study. Neurons are involved in 3 different networks/circuits in the crab, C. borealis: the pyloric network (anterior burster (AB), PD, LPG, LP, and PY; orange box), the gastric network (LG, DG, and GM; red box) and the cardiac ganglion network (Bottom). Note the time scale difference in the long-lasting bursts of the gastric cells (red box) relative to the pyloric cells (orange box). Some neurons (interneuron 1 (INT1), IC, VD, and MG) participate in both gastric and pyloric network activity and are noted in the purple box. LC motor neurons of the cardiac ganglion are used as an “outgroup” to compare expression patterns of motor neurons from a distinct ganglion (cardiac ganglion). Each of the representative recordings is independent as an example of individual cell output, and simultaneous network activity is not plotted here. Thus, none of the phase relationships of these units within their respective rhythms is implied in any of the recordings.