Fig 12. The encoder-decoder gain ratio ΦZ as the number of core neurons in the encoding set Z increases (yellow curve).
The maximum value of ΦZ is about 8.2 when Z includes the first 16 core neurons. Based on the cost framework of Section “Encoder-Decoder Architecture”, this means that the hourglass organization of the C. elegans connectome reduces the sensory-to-motor information processing cost eight-fold. The figure also shows the three relevant cost terms: cost of encoding the information provided by sensory neuron using neurons in Z (magenta), cost of decoding that information to drive all motor neurons (green), and cost of processing pathways that bypass the core (blue).