Figure 5. Identifying network models underlying an experimentally observed pyloric rhythm in the crustacean stomatogastric ganglion.

(a) Simplified circuit diagram of the pyloric network from the stomatogastric ganglion. Thin connections are fast glutamatergic, thick connections are slow cholinergic. (b) Extracellular recordings from nerves of pyloric motor neurons of the crab Cancer borealis (Haddad and Marder, 2018). Numbers indicate some of the used summary features, namely cycle period (1), phase delays (2), phase gaps (3), and burst durations (4) (see Materials and methods for details). (c) Posterior over 24 membrane and seven synaptic conductances given the experimental observation shown in panel b (eight parameters shown, full posterior in Appendix 1—figure 11). Two high-probability parameter sets in purple. Inset: magnified marginal posterior for the synaptic strengths AB to LP neuron vs. PD to LP neuron. (d) Identifying directions of sloppiness and stiffness. Two samples from the posterior both show similar network activity as the experimental observation (top left and top right), but have very different parameters (purple dots in panel c). Along the high-probability path between these samples, network activity is preserved (trace 1). When perturbing the parameters orthogonally off the path, network activity changes abruptly and becomes non-pyloric (trace 2).